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Network Plan Part 13 - CO, NOx, Pb, PM, SO2, Ozone

4. Criteria Contaminants

EPA is required to set National Ambient Air Quality Standards (NAAQS) for wide-spread pollutants from numerous and diverse sources considered harmful to public health and the environment. The Clean Air Act established two types of national air quality standards. Primary standards set limits to protect public health, including the health of "sensitive" populations such as asthmatics, children, and the elderly. Secondary standards set limits to protect public welfare, including protection against visibility impairment, damage to animals, crops, vegetation, and buildings. The Clean Air Act requires periodic review of the science upon which the standards are based and the standards themselves. Listed below are the NAAQS for six principal pollutants, which are called "criteria" pollutants.

Table 4.1 National Ambient Air Quality Standards
Pollutant Primary Standards Secondary Standards
Level Averaging Times Level Averaging Times
Carbon Monoxide 9 ppm (10 mg/m3) 8-hour(1) None
35 ppm (40 mg/m3) 1-hour(1)
Lead 0.15 µg/m3(2) Rolling 3-month Average Same as Primary
Nitrogen Dioxide 53 ppb Annual (Arithmetic Mean) Same as Primary
100 ppb 1-hour(3) None
Particulate Matter (PM10) 150 µg/m3 24-hour(4) Same as Primary
Particulate Matter (PM2.5) 12.0 µg/m3 Annual(5) (Arith. Mean) Same as Primary
35 µg/m3 24-hour(6) Same as Primary
Ozone 0.075 ppm (2008 std) 8-hour(7) Same as Primary
0.08 ppm (1997 std) 8-hour(8) Same as Primary
0.12 ppm 1-hour(9)
Not applicable in NYS
Same as Primary
Sulfur Oxides 75 ppb 1-hour(10) 3-hour(1) 0.5 ppm (1300 µg/m3)

(1) Not to be exceeded more than once per year.
(2) Effective 1/12/2009, replaces the previous quarterly average value of 1.5µg/m3.
(3) To attain this standard, the 3-year average of the 98th percentile of the daily maximum 1-hour average at each monitor within an area must not exceed 100 ppb (effective January 22, 2010).
(4) Not to be exceeded more than once per year on average over 3 years.
(5) To attain this standard, the 3-year average of the weighted annual mean PM2.5 concentrations from single or multiple community-oriented monitors must not exceed 12.0µg/m3. Effective March 18, 2013.
(6) To attain this standard, the 3-year average of the 98th percentile of 24-hour concentrations at each population-oriented monitor within an area must not exceed 35 µg/m3(effective December 17, 2006).
(7) To attain this standard, the 3-year average of the fourth-highest daily maximum 8-hour average ozone concentrations measured at each monitor within an area over each year must not exceed 0.075 ppm (effective May 27, 2008).
(8) (a) To attain this standard, the 3-year average of the fourth-highest daily maximum 8-hour average ozone concentrations measured at each monitor within an area over each year must not exceed 0.08 ppm.
(b) The 1997 standard-and the implementation rules for that standard-will remain in place for implementation purposes as EPA undertakes rulemaking to address the transition from the 1997 ozone standard to the 2008 ozone standard.
(c) EPA is in the process of reconsidering these standards (set in March 2008).
(9) (a) The standard is attained when the expected number of days per calendar year with maximum hourly average concentrations above 0.12 ppm is < 1.
(b) As of June 15, 2005 EPA revoked the 1-hour ozone standard in all areas except the 8-hour ozone nonattainment Early Action Compact (EAC) Areas.
(10) Effective August 23, 2010. To attain this standard, the 3-year average of the 99th percentile of the daily maximum 1-hour average at each monitor within an area must not exceed 75 ppb.

4.1 Carbon Monoxide

Carbon monoxide, a colorless and odorless gas, is produced as a primary pollutant during the combustion of fossil and biomass fuels. Vegetation also can emit CO directly into the atmosphere as a metabolic by-product. Sources such as motor vehicles, non-road combustion engines or vehicles, and biomass burning can cause high concentrations of CO in the outdoor environment. Indoor sources include unvented, malfunctioning, or misused combustion appliances, combustion engines in garages or basements, and tobacco combustion. In both of these environments, CO is of direct concern because of the health effects that can result from human exposure to these high concentrations.

CO enters the bloodstream through the lungs and reduces oxygen delivery to the body's organs and tissues. The health threat from levels of CO sometimes found in the ambient air is most serious for those who suffer from cardiovascular disease such as angina pectoris. At much higher levels of exposure not commonly found in ambient air, CO can be poisonous, and even healthy individuals may be affected. Visual impairment, reduced work capacity, reduced manual dexterity, poor learning ability, and difficulty in performing complex tasks are all associated with exposure to elevated CO levels.

There are two primary NAAQS for ambient CO: a 1-hour average of 35 ppm and an 8-hour average of 9 ppm. These concentrations are not to be exceeded more than once per year. There currently are no secondary standards for CO.

Motor vehicle exhaust contributes about 60 percent of all CO emissions nationwide. High concentrations of CO generally occur in areas with heavy traffic congestion. Other sources of CO emissions include industrial processes, non-transportation fuel combustion, and natural sources such as wildfires. Peak CO concentrations typically occur during the colder months of the year when CO automotive emissions are greater and nighttime inversion conditions are more frequent.

Technological advancements in pollution control have brought about a downward trend for ambient CO concentrations over the past few decades. According to EPA estimates, annual CO emissions decreased from 197.3 million tons in 1970 to 89 million tons in 2005 nationally.

The number of monitors and concentration trends chart over the years in New York State are depicted in Figure 4.1. It clearly demonstrates that the current ambient levels of CO are well below the NAAQS, in spite of the continual increase in automobiles and vehicle-miles traveled in the State. As of 2002, all counties in the State have achieved attainment designation.

Carbon monoxide monitors and concentration trends

Figure 4.1 Carbon Monoxide Monitors and Concentration Trends

NYSDEC uses TEI Model 48C instruments that employ the NDIR gas filter correlation method for the continuous measurement of CO. Currently there are seven CO monitors in operation statewide as shown in Figure 4.2.

Map of NYS showing the location of CO monitoring sites

Figure 4.2 Location Map for Carbon Monoxide Monitoring Sites

4.2 Nitrogen Dioxide

Many chemical species of nitrogen oxides (NOx) exist, but the air pollutant species of most interest from the point of view of human health is nitrogen dioxide (NO2). Nitrogen dioxide is soluble in water, reddish-brown in color, and a strong oxidant.

Nitrogen dioxide is an important atmospheric trace gas, not only because of its health effects but also because (a) it absorbs visible solar radiation and contributes to impaired atmospheric visibility; (b) as an absorber of visible radiation it could have a potential direct role in global climate change if its concentrations were to become high enough; (c) it is, along with nitric oxide (NO), a chief regulator of the oxidizing capacity of the free troposphere by controlling the build-up and fate of radical species, including hydroxyl radicals; and (d) it plays a critical role in determining ozone (O3) concentrations in the troposphere because the photolysis of nitrogen dioxide is the only key initiator of the photochemical formation of ozone, whether in polluted or unpolluted atmospheres.

Natural sources include intrusion of stratospheric nitrogen oxides, bacterial and volcanic action, and lightning. The major source of anthropogenic emissions of nitrogen oxides into the atmosphere is the combustion of fossil fuels in stationary sources (heating, power generation) and in motor vehicles (internal combustion engines).

In most ambient situations, nitric oxide is emitted and transformed into nitrogen dioxide in the atmosphere. Oxidation of nitric oxide by atmospheric oxidants such as ozone occurs rapidly, even at the low levels of reactants present in the atmosphere. Consequently, this reaction is regarded as the most important route for nitrogen dioxide production in the atmosphere.

Other contributions of nitrogen dioxide to the atmosphere come from specific non-combustion industrial processes, such as the manufacture of nitric acid, the use of explosives and welding.

Indoor sources include tobacco smoking and the use of gas-fired appliances and oil stoves.

Nitrogen dioxide is the most widespread and commonly found nitrogen oxide and is a matter of public health concern. The most troubling health effects associated with short term exposures (i.e., less than 3 hours) to NOx at or near the ambient NOx concentrations seen in the United States include cough and increased changes in airway responsiveness and pulmonary function in individuals with preexisting respiratory illnesses, as well as increases in respiratory illnesses in children 5 to 12 years old.. Evidence suggests that long-term exposures to NOx may lead to increased susceptibility to respiratory infection and may cause structural alterations in the lungs.

Atmospheric transformation of NOx can lead to the formation of ozone and nitrogen-bearing particles (e.g., nitrates and nitric acid). As discussed in the ozone and particulate matter sections of this document, exposure to both PM and O3 is associated with adverse health effects.

Nitrogen oxides contribute to a wide range of effects on public welfare and the environment, including global warming and stratospheric ozone depletion. Deposition of nitrogen can lead to fertilization, eutrophication, or acidification of terrestrial, wetland, and aquatic (e.g., fresh water bodies, estuaries, and coastal water) systems. These effects can alter competition between existing species, leading to changes in the number and type of species (composition) within a community. For example, eutrophic conditions in aquatic systems can produce explosive algae growth leading to a depletion of oxygen in the water and/or an increase in levels of toxins harmful to fish and other aquatic life.

The level for both the primary and secondary NAAQS for NO2 is 0.053 ppm annual arithmetic average (mean), not to be exceeded. This past January EPA revised the NAAQS to include an hourly standard of 0.100 ppm. Figure 4.3 shows the number of monitoring sites and NO2 concentration trends over the years. The current ambient levels of NO2 observed in New York State are well below the NAAQS.

Nitrogen dioxide monitors and concentration trends

Figure 4.3 Nitrogen Dioxide Monitors and Concentration Trends

In New York, the TEI Model 42C instruments are deployed for continuous NO2 measurements using the gas phase chemiluminescence method. Currently there are four NOx monitoring sites statewide, and NO/NOy monitors in Rochester, Pinnacle, and Queens College (both NO2 and NOy) as shown in Figure 4.4. NO/NOy measurements are included within the NCore multi-pollutant site requirements and the PAMS program. These NO/NOy measurements will produce conservative estimates for NO2 that can be used to ensure tracking continued compliance with the NO2 NAAQS. NO/NOy monitors are used at these sites because it is important to collect data on total reactive nitrogen species for understanding O3 photochemistry.

The EPA considered setting a secondary standard for NOx and SOx that would specifically target the impact of acidic deposition on wilderness areas. The EPA ultimately decided that there was not enough information at this time to tie specific water quality thresholds with ambient air concentrations. In the July 2011 final rule for NOx and SOx, the EPA stated that they would set up a monitoring program in sensitive areas to collect information to link water quality impacts to ambient air quality measurements. The NYSDEC is participating in this pilot monitoring program in the Adirondacks. Additional monitoring equipment has been installed at several sites to determine the concentrations of gasses and particles including ammonia. These data will be used in the future to inform the next review of the NOx/SOx standard.

Map of NYS showing the location of NOx monitoring sites

Figure 4.4 Location Map for Nitrogen Oxides Monitoring Sites

Although ambient NO2 levels are not expected to contravene the NAAQS, monitoring is necessary due to it being an ozone precursor, and to track the effectiveness of emission reduction programs. Under the new NOx rule that became effective January 22, 2010 each MSA with population larger than 500,000 will be required to operate a near-road monitor beginning in 2013. New York State will need to establish such a site in each of the following areas: Albany-Schenectady-Troy, Buffalo-Niagara Falls, Poughkeepsie-Newburgh-Middletown, Nassau-Suffolk, New York-White Plains, Rochester and Syracuse. One urban community wide monitor will be located in each of the three MSAs with population greater than 1 million: New York, Buffalo and Rochester. Furthermore, the Regional Administrators at their discretion, have the authority to require 40 additional sites nationwide in communities where susceptible and vulnerable populations are located. On March 7, 2013, EPA issued a final rule to revise the deadlines by which the near-road monitors within the NO2 monitoring network are to be operational. States and local agencies will begin operating the near-road component of the NO2 network in phases between January 1, 2014 and January 1, 2017. This replaces the 2010 rule requirement that originally required all new NO2 monitors to begin operating on January 1, 2013. New York is working closely with EPA Region 2 to implement this rule. We have identified possible sites in New York and Buffalo and anticipate operation by 2014. We are actively pursuing a suitable site location in Rochester.

4.3 Lead

Elemental lead (Pb) possesses an array of useful physical and chemical properties, making it among the first metals to be extracted and used by humankind. It has a relatively low melting point (327.5°C), is a soft, malleable, and ductile metal, a poor electrical conductor, and is easily cast, rolled and extruded. Although sensitive to environmental acids, after exposure to environmental sulfuric acid (H2SO4), metallic Pb becomes impervious to corrosion due to weathering and submersion in water. This effect is due to the fact that Pb lead sulfate (PbSO4), the relatively insoluble precipitate produced by reaction of Pb with H2SO4, forms a protective barrier against further chemical reactions. This aspect of its chemistry made Pb especially convenient for protective surface coatings (e.g. paint), roofing, containment of corrosive liquids, and (until the discovery of its adverse health effects), construction of water supply systems.

Pb will only exist in the vapor phase at or above 1750°C. Therefore, at ambient atmospheric temperatures, elemental Pb will deposit to surfaces or exist in the atmosphere as a component of atmospheric aerosol.

Exposure to lead occurs through ingestion of lead in food, water, soil, or dust and through inhalation. It accumulates in the blood, bones, and soft tissues. Lead can also adversely affect the kidneys, liver, nervous system, and other organs. Excessive exposure to lead may cause neurological impairments such as seizures, mental retardation, and/or behavioral disorders. Even at low doses, Pb exposure is associated with changes in fundamental enzymatic, energy transfer, and homeostatic mechanisms in the human body. Additionally, even low levels of Pb exposure may cause central nervous system damage in fetuses and children. Recent studies show that neurobehavioral changes may result from Pb exposure during the child's first years of life and that lead may be a factor in high blood pressure and subsequent heart disease.

Airborne lead can also have adverse impacts on the environment. Wild and domestic grazing animals may ingest lead that has deposited on plant or soil surfaces or that has been absorbed by plants through leaves or roots. Animals, however, do not appear to be more susceptible or more sensitive to adverse effects from lead than are humans. Therefore, the secondary standard for lead is identical to the primary standard.

In November of 2008 EPA published the final rule for the revision of the NAAQS for lead. The primary lead standard was revised to 0.15µg/m3 in total suspended particles (Pb-TSP). The averaging time was changed to a rolling 3-month period with a maximum (not-to-be-exceeded) form, evaluated over a 3-year period. The revised secondary standard was set to be identical in all respects to the new primary standard. These new standards became effective on January 12, 2009, superseding the old standard of quarterly average concentration not to exceed 1.5µg/m3. As part of the lead monitoring requirements, monitoring agencies are required to monitor ambient air near lead sources which are expected to or have been shown to have a potential to contribute to a 3-month average lead concentration in ambient air in excess of the level of the NAAQS. At a minimum, monitoring agencies must monitor near lead sources that emit 1.0 ton per year (tpy) or more. Monitoring is also required in each CBSA with a population equal to or greater than 500,000 people as determined by the latest available census figures. Revisions to the monitoring requirements pertaining to where State and local monitoring agencies would be required to conduct lead monitoring were finalized and became effective January 26, 2011. The new regulations replaced the population oriented monitoring requirement with a requirement to add Pb monitors to the urban NCore monitors. The EPA also lowered the emission threshold from 1.0 tpy to 0.50 tpy for industrial sources of lead (e.g., lead smelters and foundries). However, the emission threshold for airports was maintained at 1.0 tpy. In addition, an airport monitoring study will be implemented to determine the need for monitoring of airports which emit less than 1.0 tpy of lead. Under this new rule lead monitoring is required for a minimum of one year at 15 additional airports that have been identified as having characteristics that could lead to ambient lead concentrations approaching or exceeding the lead NAAQS. Brookhaven and Republic airports in Suffolk County, New York have been designated as such. A 12-month monitoring study at Brookhaven Airport commenced concluded in October, 20121 and all data were submitted to AQS. The Republic Airport monitoring is expected to begin in the second quarter ofdid not start until October, 2012 due to protracted site lease negotiations.

Particulate lead samples are collected on glass fiber filters using a standard TSP high volume sampler which are subsequently analyzed by the laboratory using atomic absorption spectroscopy. Under the new rule, EPA is allowing Pb-PM10 in lieu of Pb-TSP where the maximum 3-month arithmetic mean Pb concentration is expected to be less than 0.10µg/m3 (i.e., two thirds of the NAAQS) and where sources are not expected to emit ultra-coarse Pb. The population oriented Pb monitors at the NCore or NATTS sites are located away from known sources of Pb and will utilize Pb-PM10 samplers. Figure 4.5 depicts the number of monitoring sites and lead concentration trends for New York State over the years.

Lead monitors and concentration trends

Figure 4.5 Lead Monitors and Concentration Trends

Currently there are four Pb-TSP monitors (one collocated) in operation in Middletown, where a lead acid battery recycling facility is located, and two urban CBSA monitors (low volume PM10) at the NATTS sites in the Bronx and Rochester. The source oriented monitoring sites (AQS site ID # 36-071-3001, 36-071-3002, 36-071-3004) are in place as the facility has the potential to contribute to a 3-month average lead concentration in ambient air in excess of the level of the NAAQS. Routine data review showed that during the first quarter of 2011, there were a couple of sample dates that showed high levels of lead, which would lead to contravention of the new standard. Investigations at the facility led to enforcement actions although specific causes for the observed values were not discovered. Consequently an additional low volume PM10 sampler was put in place to collect daily filter samples for mass measurement and lead analysis using XRF in August 2011. The PM10 mass data collected at this site was low and mass determination was discontinued in November 2012. The highest 3 Month average PM10 lead concentration at this site was 0.021 µgPb/m3 which is well below the standard. .

4.4 Particulate Matter

4.4.1 Total Suspended Particulate

Particulate matter is the generic term for a broad class of chemically and physically diverse substances that exist as discrete particles (liquid droplets or solids) over a wide range of sizes. Particles originate from a variety of anthropogenic stationary and mobile sources as well as natural sources. Particles may be emitted directly or formed in the atmosphere by transformations of gaseous emissions such as sulfur oxides, nitrogen oxides, and volatile organic compounds. The chemical and physical properties of PM vary greatly with time, location, meteorology, and source category, thus complicating the assessment of health and welfare effects.

EPA first established national ambient air quality standards for PM in 1971. The reference method specified for determining attainment of the original standards was the high-volume sampler, which collects PM up to a nominal size of 25 to 45 micrometers (µm), referred to as total suspended particles or TSP. The primary standards (measured by the indicator TSP) were 260µg/m3 24-hour average, not to be exceeded more than once per year, and 75µg/m3 annual geometric mean. The secondary standard was 150µg/m3 24-hour average, not to be exceeded more than once per year. These standards were in place until 1987 when EPA changed the particle indicator from TSP to PM10, the latter referring to particles with a mean aerodynamic diameter less than or equal to10 µm.

Figure 4.6 shows the number of monitoring sites and the composite annual geometric means ofTSP over the years. Trace metal analysis was also performed on the TSP filters until 1998. NYSDEC terminated the TSP sampling program when DOH could no longer provide laboratory analysis support.

Total suspended particulate monitors and concentration trends

4.6 Total Suspended Particulate Monitors and Concentration Trends

4.4.2 PM10

In 1987 EPA revised the 1971 standards in order to protect against adverse health effects of inhalable airborne particles that can be deposited in the lower (thoracic) regions of the human respiratory tract, with PM10 as the indicator. EPA established identical primary and secondary PM10 standards for two averaging times: 150µg/m3 (24-h average, with no more than one expected exceedance per year) and 50 µg/m3 (expected annual arithmetic mean, averaged over three years). These standards remained in effect until 2002, when the courts finally upheld the 1997 revisions put forth by EPA as a result of the mandated periodic scientific review. After the most recent scientific review on PM, EPA issued the final rule in December, 2006 revising the PM2.5 standards, at the same time revoking the PM10 annual standard while retaining the 24 hr standard at 150µg/m3.

Wedding & Associates PM10 Critical Flow High Volume Sampler (WED PM10 sampler) were employed for the NYSDEC network. The quartz filters were collected and submitted to the Department of Health for laboratory analysis until 2005, when support services were terminated. Figure 4.7 shows the number of monitors and the composite annual arithmetic mean for PM10.

Starting in 2004, the R&P Partisol 2025 samplers were used for manual PM10 collection by removing the PM2.5 size selective inlet. The filter cartridges are submitted to RTI (EPA contract laboratory) for mass analysis.

PM10 monitors and concentration trends

Figure 4.7 PM10 Monitors and Concentration Trends

Currently there are five such sites in operation, as shown in Figure 4.8.

Map of NYS showing location of manual PM10 monitoring sites

Figure 4.8 Location Map for PM10 Monitoring Sites

A continuous PM10 data are also obtained using Thermo Scientific 1405-DF instruments that simultaneously measure PM2.5, PM Coarse (PM10 - PM2.5) and PM10 mass concentrations at the IS 52, Queens College, and Pinnacle State Park sites.

4.4.3 PM2.5

In July 1997, EPA Administrator promulgated significant revisions to the PM NAAQS, after taking into account scientific information and assessments presented by staff, Clean Air Scientific Advisory Committee advice and recommendations, and public comments. While it was determined that the PM NAAQS should continue to focus on particles less than or equal to 10 µm in diameter, it was also determined that the fine and coarse fractions of PM10 should be considered separately. New standards were added, using PM2.5 as the indicator for fine particles; and PM10 standards were retained for the purpose of regulating coarse-fraction particles. Two new PM2.5 standards were set: an annual standard of 15 µg/m3, based on the 3-year average of annual arithmetic mean PM2.5 concentrations from single or multiple community-oriented monitors; and a 24-h standard of 65 µg/m3, based on the 3-year average of the 98th percentile of 24-h PM2.5 concentrations at each population-oriented monitor within an area. To continue to address coarse-fraction particles, the annual PM10 standard was retained, and the form, but not the level, of the 24-h PM10 standard was revised to be based on the 99th percentile of 24-h PM10 concentrations at each monitor in an area. The secondary standards were revised by making them identical in all respects to the PM2.5 and PM10 primary standards.

EPA lowered the NAAQS for PM in December of 2006 to provide increased protection of public health and welfare, respectively. EPA revised the level of the 24-hour PM2.5 standard from 65 to 35 micrograms per cubic meter (µg/m3) and retained the level of the annual PM2.5 standard at 15 µg/m3. With regard to PM10, the 24-hour standard was retained, but the annual PM10 standard was revoked. On Dec. 14, 2012 EPA further strengthened the nation's air quality standards for fine particle pollution to by revising the primary annual PM2.5 standard from 15 to 12 micrograms per cubic meter (μg/m3) and retaining the 24-hour fine particle standard of 35 μg/m3. The new standards became effective on March 18, 2013.

The NYSDEC PM2.5 monitoring network deploys a combination of filter based Federal Reference Method (FRM) samplers, continuous mass monitors, filter based speciation samplers and continuous speciation samplers. The data from the FRM samplers are used to determine if the State's air quality meets the National Ambient Air Quality Standards (NAAQS). The continuous mass sampler data are used for the reporting of near real-time air quality data for health related warnings and forecasts. The speciation filter sampler data are used to determine the chemical constituents that make up PM2.5. The continuous speciation data are used to examine the short term fluctuations in the concentrations of individual species or components that make up PM2.5.

PM Monitoring Objectives

The principal objective of the PM2.5 monitoring network is to determine the exposure of the State's population to ambient PM2.5. This objective is the primary focus of the FRM filter based samplers as well as for the continuous mass monitoring network. The protocols and equipment used for the FRM network are meticulously specified in the Code of Federal Regulations (CFR) to insure that the measurements are consistent from one State to another. The continuous mass monitoring instruments cannot accurately provide data for direct comparison with the NAAQS but these instruments actually provide the most useful data for population exposure. The continuous PM2.5 data is updated every hour for near real-time health related warnings, PM2.5 forecasts and updates as to current pollution concentrations.

The NYSDEC has attempted to adjust the PM2.5 network in light of EPA expectations, updated regulations and prioritized funding. The FRM network consisted of 40 sites when it was fully established using the original design criteria from 1998. Since then the number of sites have been reduced because fewer sites were required to determine compliance with the Annual PM2.5 NAAQS. The latest revisions to the Federal regulations have reduced the number of required monitors even further. These new requirements base the number of required monitors on population and the expected PM2.5 concentration. The NYSDEC network exceeds these requirements in all areas that are expected to be near or above either the Annual or Daily PM2.5 standard.

The other monitoring objectives for the PM2.5 network include transport and background monitoring. Transport monitoring sites are sites that are situated so that the data are representative of the air masses moving into the State from areas upwind. These sites are important because the sources of PM2.5 that are outside of New York can contribute to New York's PM2.5 ambient concentration. Background monitoring sites are sites that are representative of PM2.5 concentrations that are generally not related to specific sources but impact wide areas. The concentrations measured at these background sites generally represent the lowest expected PM2.5 concentrations in New York State.

Monitoring Scale and Representativeness

The geography of New York State encompasses a lake shore to the west, plateaus and rolling hills in the center, mountains to the northeast and south and sea shores to the southeast. All of these areas have varying population densities and meteorology. The populations living in these areas are exposed to PM2.5 that is generated locally as well as from PM2.5 that is transported from areas outside of their region.

The actual design of the network is a compromise that minimizes the number of monitoring locations while ensuring that the measured concentrations for each area are indicative of actual population exposures. Each sampler is assigned a scale or "zone of representativeness" when it is installed. The scale determines how large a geographical area the resulting data will represent.

EPA has defined ambient monitoring scales as:

Microscale: Represents (10 - 100 meters)
Middle Scale: Represents (100 - 500 meters)
Neighborhood Scale: Represents (500 meters - 4 km)
Urban Scale: Represents (4 - 100 km)
Regional Scale: Represents (100 to 1000 km)

The scale of the FRM monitoring sites that have population exposure as their objective is Neighborhood or Urban. The definitions of scale primarily serve to identify the site's sensitivity to individual sources. A monitoring site that is routinely impacted by a specific source has a much smaller "scale" than a site that only sees an effect from numerous widespread sources. The FRM sites in New York State are located in places that will likely have high concentrations and large monitoring scales. This ensures that the public is not exposed to higher ambient PM2.5 concentrations than the concentrations from the FRM network reported for their area.

The PM2.5 monitoring network works well for determining average ambient exposures for most of the State's population. The limitations of the network stem from the inability to monitor in smaller scales such as Middle and Microscale. An example of an urban microscale influence not addressed by the network would be PM2.5 emissions from traffic in a street canyon. Certainly if New York residents spent much of their time in this type of confined area, then their exposure to ambient PM2.5 would be considerably higher than that indicated by the closest neighborhood or urban scale monitor. Similarly, a person in a rural valley area subject to daily woodsmoke would also be exposed to higher PM2.5 concentrations than those measured at the nearest Neighborhood or Urban scale monitor.

The PM2.5 ambient monitoring network is also not able to determine the population's overall exposure to PM2.5. Personal habits such as smoking and occupations such as mining, farming and construction can lead to much higher exposures to PM2.5 than that of the majority of the population. Other factors such as widely varying indoor PM2.5 concentrations can lead to uncertainty in overall PM2.5 exposures.

PM2.5 Monitoring Instrumentation

The filter based FRM samplers used in New York are the Model 2025 sequential samplers made by the Thermo Environmental Company (Franklin, MA). The sampler has been designated by EPA as a reference method instrument for PM2.5 particle collection. The designation is: RFPS-0498-118.

Currently there are 19 FRM monitors in operation statewide, as shown in Figure 4.9.

Map of NYS showing manual PM2.5 monitoring sites

Figure 4.9 Site Location Map of Manual PM2.5 (FRM) Monitoring Network

Figure 4.10 below shows the number of manual PM2.5 monitoring sites and the composite annual arithmetic means in New York State since the network was implemented in 1998.

Monitors and concentration trends for PM2.5 in NYS

Figure 4.10 PM2.5 Monitors and Concentration Trends

The continuous mass monitoring instruments used in New York are the TEOM 1400ab also made by the Thermo Environmental Company. These instruments have received designation by EPA for PM10 but not for PM2.5. PM2.5 is more difficult to measure than PM10 with automated samplers because PM2.5 contains a higher fraction of volatile components. The heated measurement sensor for the TEOM reduces the amount of volatile mass measured as compared to filter based FRMs. The NYSDEC utilizes non-linear data adjustments to make the TEOM data more comparable with the FRM data. The adjusted data are used for public reporting and forecasts of PM2.5 concentrations.

The NYSDEC uses seven MetOne SuperSass and URG 3000N samplers for the collection of samples for the speciation of PM2.5. The samplers collect 3 and 1 filter samples respectively every third day or sixth day for a period of 24 hours. The samples are then sent to an EPA contract laboratory for chemical analysis. There are over fifty species consisting of ions, metals and carbon species quantified by the analyses.

4.4.4 Continuous PM Monitoring

Continuous mass monitoring is performed primarily with a network of TEOM 1400ab instruments. In addition, there are three Thermo Scientific 1405-DF's deployed (IS 52, Queens College, and Pinnacle) to simultaneously measure PM2.5, PM Coarse (PM10 - PM2.5) and PM10 mass concentrations. This element of the PM2.5 monitoring network provides the data used for public reporting purposes including; the NYSDEC website, the AIRNow website and for PM2.5 forecasting. The data from the TEOMs are polled and reported every hour to insure that the public has access to the most recent air quality information.

The TEOM data are compared to the filter based FRM data on an annual basis. The comparison allows the analysts to create non-linear correction factors that modify the TEOM data to more closely resemble FRM data. This is necessary because FRM data is not available for near real-time public reporting purposes. EPA has recently recognized the value of these data adjustments and has created new method codes so this adjusted data can be submitted to the AQS database. The NYSDEC now submits TEOM data from each site in its original unadjusted format as well as the adjusted data to match more closely with the FRM.

There are 26 continuous PM2.5 monitoring sites are depicted in Figure 4.11.

Map of NYS showing locations of continuous PM2.5 monitoring sites

Figure 4.11 Site Location Map of Continuous PM2.5 (TEOM) Monitoring Network

The NYSDEC also operates some of the newest continuous mass monitors which have undergone Federal Equivalent Method (FEM) designation. These instruments collect more of the volatile PM mass that the filter based FRM may or may not retain depending on the environmental conditions during and after the period in which the filter sample was collected. The Department has been evaluating the technological improvements that have led to the current PM2.5 continuous FEMs for more than 10 years. The Thermo Scientific 1405-DF FEM performed better than the other instruments in on-site deployments at urban and rural locations in the state. The Department purchased several of these but they have not operated reliably and have not produced data that compares acceptably with the FRM. The equipment manufacturer is aware of the issues and seems to be working towards resolutions of the problems. The Department will continue to rely on the FRM network to provide data for comparison with the ambient PM2.5 air quality standards. Currently there are three 1405-DF's deployed (IS 52, Queens College, and Pinnacle) to simultaneously measure PM2.5, PM Coarse (PM10 - PM2.5) and PM10 mass concentrations. The Department does not intend to use data collected by the FEMs for comparison to the NAAQS.

4.4.5 Speciation

Speciation monitoring is performed with a network of seven MetOne SuperSass samplers. There are eight sites in New York State operating with the Speciation Trends Network (CSN) sampling protocol. Five operate on a 1/3 day schedule and two operate on a 1/6 day schedule. All of these sites host collocated FRM and continuous mass monitoring instruments. A rural and an urban site also host collocated IMPROVE protocol samplers. The data from these sites is used to assist in the comparison between CSN and IMPROVE data sets. The goal of the urban installation will be to further relate the mostly rural IMPROVE network to the mostly urban CSN network.

In order to address inconsistencies in carbon sampling and analysis procedures used in urban CSN/SLAMS and rural IMPROVE programs, EPA determined that the URG sampler would be used at all CSN sites. The conversion was completed 2008 for all of the NY sites.

Figure 4.12 shows the seven CSN sites currently in operation.

Map of NYS showing location of PM2.5 speciation monitoring sites

Figure 4.12 Location Map of Speciation Sampling Sites

4.4.6 Continuous Speciation

The NYSDEC recognizes the value of high temporal measurements (hourly or higher) of PM2.5 species. This data is useful for the examination of pollutant trends (and temporal patterns) and can provide information necessary for identification of pollutant sources. This is critically important for areas facing non-attainment for the PM2.5 NAAQS. Identifying seasonality of species is necessary to develop control strategies. Long term monitoring is vital to this effort because in addition to changes in source emissions, variations in meteorology also affect ambient pollutant concentrations (e.g. wetter than average conditions lead to a washout of pollutants and a lowering of ambient concentrations).

The NYSDEC continuous speciation program is expanding and currently includes monitoring at urban and rural locations. Sulfate, nitrate, organic carbon, elemental carbon and black carbon species data are collected at hourly or higher frequency. In this manner both the regional and inter-urban variability of these species are being investigated. The NYSDEC uses instruments to examine the species of PM2.5 on a higher frequency than what is available from the filter based speciation sampling network. This continuous speciation data is useful in the examination of source strengths and the relationship between pollutant concentrations and meteorology. The operation of continuous speciation equipment is also less expensive than long term filter species measurements due to the high costs associated with filter lab analysis. Operation of continuous speciation in conjunction with 24-hr CSN sampling is beneficial in accounting for biases in measurements when a change to the CSN method occurs. This is demonstrated in the case of CSN carbon which was changed to the IMPROVE method in 2007. Long term collocated continuous carbon measurements prior to and following this change are being used to assess the bias between the old and the new carbon methods. This data will be important in determining the long term trends in PM2.5 carbon species.

NYSDEC has been using the continuous speciation data in NYC to examine temporal patterns such as diurnal and day of week patterns of aerosol species related to source strengths and meteorology. For example elemental carbon, black carbon and primary pollutant NOx in NYC track throughout the day with peak concentrations in the morning coincident with the early commute period. Mobile emissions in the early morning occur into a shallow boundary layer which concentrates pollutants near ground level. An elevation in boundary layer height during the day leads to a dispersion of pollutants and a less pronounced afternoon/evening peak. Concentrations of these species are also higher on weekdays compared to weekends indicating that local mobile emissions are a significant source of these species. During winter months organic carbon sometimes shows similar patterns to EC and NOx reflecting the primary organic component most likely from mobile emissions. Throughout the year however organic carbon does not track the primary pollutants but is more correlated with PM2.5 mass (and sulfate during summer months) indicating that there is a significant regional or non-local contribution to organic carbon measured in NYC. Our continuous speciation measurements also reveal temporal patterns in particle nitrate. In cooler months PM2.5 nitrate has a broader peak than EC which appears later in the morning, consistent with photochemical and secondary aerosol production. During the warm season nitrate concentrations are significantly lower and the late morning nitrate peak (observed in winter) is not observed in the warm season because as temperatures rise during the day aerosol nitrate reverts back to its precursors (nitric acid and ammonia).

Continuous data can also be used to capture the full extent of regional or local plumes that would normally be missed by the 24-hr filter sampling network. It allows us to study plume events and how meteorology can affect measurements. One can also differentiate between plumes which are short term of a few hours long (e.g. plumes from oil boiler emissions) likely driven by carbon versus those that are more regionally driven by sulfate in summer. High temporal pollutant data is also beneficial for public health effect studies that often require resolving confounding factors.

Recently concerns have been raised regarding potential adverse health effects associated with residential wood burning. Wood smoke contains fine particulate matter which can cause short-term effects such as eye, nose, throat and lung irritation, coughing, sneezing, runny nose and shortness of breath. Exposure to PM2.5 also can affect lung function and worsen medical conditions such as asthma, allergies and heart disease. Long term exposure to fine PM may increase the risk from chronic bronchitis, reduce lung function and increase mortality from lung cancer and heart disease. In addition, wood smoke contains known human carcinogens including benzene, formaldehyde, dioxins and polycyclic aromatic hydrocarbons.

BAQS staff in collaboration with Clarkson University researchers were able to successfully characterize the ambient impact of residential wood combustion using dual wavelength (370 and 880 nm) aethalometer measurements in conjunction with filter measurements of levoglucosan and potassium, markers for wood smoke. The study, which was conducted from October 2009 to October 2010 in Rochester, showed that the wood smoke component of black carbon is most evident from October to March during the late evening hours on cold weekend nights. Residential wood combustion was estimated to contribute 17% to the PM2.5 mass during winter at the Rochester study site.

4.4.7 Additional Monitoring Initiatives

The NYSDEC has been active in additional research and monitoring beyond the mandated Federal requirements. Some of this work has been collaborative with goals ranging from collecting data with the newest technologies, to providing support for health studies to evaluating new monitoring instruments. Other projects undertaken by the NYSDEC such as adding additional monitoring after the World Trade Center attack or monitoring before and after the cap was installed on the Fresh Kills landfill could not have been undertaken by other Agencies.

4.4.7.1 PM2.5 Technology Assessment and Characterization Study-New York Supersite

The largest collaborative monitoring project undertaken by the NYSDEC and State University of New York's Atmospheric Science Research Center (SUNYA-ASRC) was the Supersite program known as PMTACS. The 5 year monitoring initiative leveraged resources from EPA, NYSERDA and the NYS Environmental Bond Act to obtain detailed highly resolved pollutant measurements from NYC, Whiteface Mountain and an upwind rural site south-west of Corning, NY. This monitoring project also involved participants from the NYSDOH, Penn State University, Aerodyne Research Inc. and Clarkson University. The project's website lists many of the program details: http://www.asrc.cestm.albany.edu/pmtacsny/index.html

Some of the instrument method development work initiated under this program has continued after the conclusion of the PMTACS program. This shared effort includes method development work on trace gas monitors, continuous organic carbon monitors, continuous particulate sulfate instruments, continuous particulate nitrate and ammonia instruments. All of these instruments will be needed as NYSDEC designs PM control strategies for non-attainment areas within New York State.

The current research undertaken by this collaboration involves small particle and precursor gas concentration measurements from rural and urban locations in NY State. NYSERDA has provided funds for this work which includes an intensive monitoring campaign over several weeks this summer in New York City. The past summer measurements in conjunction with some on-going measurements are being used to compare with data taken at an urban NYSDEC monitor and those from a mobile van traveling on nearby highways. These studies will help to determine the impacts of mobile sources at fixed neighborhood monitors.

4.4.7.2 Organic Carbon: Molecular Marker Characterization

The NYSDEC collaborated with Rutgers, Drexel, NESCAUM, NJDEP and CTDEP on a project called the Speciation of Organics for Apportionment of PM2.5 in the New York City Area (SOAP). The field portion of the project was conducted from May 2002 to May 2003. It operated at four sites: Queens, NYC (high density urban residential); Elizabeth, NJ (adjacent to the NJ Turnpike); Westport, CT (downwind NYC); and a regional background site in Chester, NJ (upwind NYC). The study's chief objectives were to expand the chemical characterization of organic compounds and to estimate the source contributions of carbonaceous fine particles at urban and background monitoring sites.

This project continued at a site in NYC and a rural site in Addison, south-west of Corning, NY during 2005 to 2007. Sampling for this project has been completed. The data from this project will provide information about the significance of sources of organic carbon particulate in both urban and rural areas in New York. This type of information will be used to assess the potential viability of local and wide range PM2.5 control strategies.

4.4.7.3 PM Coarse Monitoring

The NYSDEC is taking an active role in advance of an upcoming EPA directive to monitor for PM Coarse (PM10 - PM2.5). Filter based monitoring was initiated in NYC and in Niagara Falls to determine approximate concentrations of PM Coarse. This information was used to assess PM Coarse elemental concentrations. The NYSDEC has also used this data to comment on the proposed PM Coarse standard and network design that were recently part of the draft CFR Parts 53 and 58. Filter based 1 day in 6 PM Coarse monitoring is also underway at the Rochester and IS52 NATTs sites and at the NCore site in Queens.

The NYSDEC has also supported the development of new automated near real-time PM instruments. The NYSDEC is evaluating the 1405-DF Federal Equivalent Method (FEM) PM Coarse instruments at 3 locations in New York State. Data from the filter based samplers already operating at the site will be used to evaluate the performance of these instruments. The benefit of this work for the NYSDEC is that if successful, the instruments can provide high frequency data that can also be used for comparison to the PM2.5 and PM10 NAAQS.

4.4.8 Air Pollution and Environmental Conditions
4.4.8.1 NYC Micro-scale Street Canyon Monitoring

The NYSDEC responded to a request by EPA to install 2 street level monitors in an urban area in NYC. The areas are known as canyons due to the tall buildings on either side of the street. The PM10 data collected at the one remaining site is used to evaluate the differences between data collected at very low elevations, close to high traffic roadways, and the monitors that are properly sited in the rest of the monitoring network.

4.4.8.2 Rochester PM Center Clarkson, Univ. of Rochester Medical Center

The NYSDEC collaborates with researchers from the University of Rochester Medical Center and Clarkson University who have been awarded a second PM health research grant from EPA. Their work focuses on the pathways and effects from PM pollution on the cardiovascular system. The NYSDEC provides data and support for a fine particle classifying instrument at a monitoring location near the University of Rochester.

4.4.8.3 Air Pollution Microscopy

In addition to performing toxics and acid deposition laboratory analyses, BAQS Monitoring Support Section at the Rensselaer facility operates a variety of analytical microscopes for particle analysis. These instruments include: Smiths Detection Inc. IlluminatIR Fourier Transform microscope; JEOL 6490LV Scanning Electron Microscope (SEM) with a Brucker Spirit Energy Dispersive Spectroscopy (EDS) System. Together with optical microscopes, staff can provide data on size, morphology, elemental, chemical, and other physical properties of particulate samples of size down to 1 µm in diameter. The information obtained is valuable for the understanding of source origin and provides important input for apportionment analysis.

Ultra fine particles (<0.1 µm), primarily generated from combustion processes, including stationary fossil-fuel electric power generation, industrial processes, boilers, and gasoline and diesel engines, are an important component of PM2.5. Scientists are becoming increasingly more interested in these ultra fine or "Nano" size particles. Recently NYSDEC acquired a VEECO Nanoscope Multimode Atomic Force Microscope (AFM) for the analysis of these extremely small particles. With the addition of this new instrument, we are now able to look at particulate an order of magnitude smaller than what the Scanning Electron Microscope (300,000× mag vs. 3,000,000× mag) can provide. Whereas the SEM specializes in particles in the 2.5 micron range, the Nanoscope is currently analyzing particles in the 25-50 nanometer range. Particle size, surface texture and roughness are now available on such particles as diesel exhaust, wood smoke, and other products of combustion.

Recently NYSDEC acquired the Olympus LEXT Laser Confocal Microscope (LCM). It is designed to obtain images of ultrafine particles at ranges smaller than what can be seen with our Scanning Electron Microscope (SEM) and larger than what we can see with Atomic Force Microscope (AFM). It is the perfect fit between these two pieces of instrumentation and will complement both the AFM and SEM. Each method can "see" in the size range that the other cannot. The LCM works on particles between 500 nm and 200 microns, so it works in between the two.

The intended use of this instrument will provide information:

on the use of alternative fuels such as biodiesel and ethanol, as well as their use with different emission after-treatment strategies. Little to no information is currently available on the effect of such fuels on particle morphology.

to refine our methodologies for acquiring filter samples for microscopic examination and in performing these examinations. Future samples could potentially be taken both from direct mobile source emissions and also from ambient samplers deployed in the monitoring network.

to re-evaluate our earlier ultrafine particle measurements. For example, earlier results suggest the presence of a secondary small particle mode in biodiesel emissions (smaller particles pose greater risks of health effects). Microscopic examination could provide evidence to either support or dismiss this finding.

4.4.8.4 Ultrafine Particulate Monitoring

NYSDEC first began ultrafine particulate monitoring with the deployment of a TSI Model 3031 Ultrafine Particle Monitor (UPM) at Queens College in June of 2009. This instrument provides continuous measurements of size distribution and particle number concentrations of fine particles below1 micron, in the range from to 20 to 500 nanometers. The Queens College NCore site was selected for the UPM so as to complement a suite of parameters already being measured there. Concurrently a demo UPM unit on loan for one year from the manufacturer was installed at the Eisenhower Park location in Nassau County, which is expected to have a significant impact from mobile sources. Preliminary data suggest that the ultrafine particles are to a large extent regional in nature and less impacted by local mobile sources. The particle counts and size distributions for the two sites are similar, and also track the PM2.5 profile in some cases. It is possible that the mobile signal is damped out due to the siting of the monitor, as the inlet probe height may not be optimal and there may be interference from nearby trees. In addition, a resource recovery facility located about ¼ mile west of the site, as well as other local sources (wood-fired pizza ovens, etc.) may influence the measurements. Alternate explanations may be that mobile ultrafine emissions are predominantly smaller than the 20 nanometer cut-off point or affect the measurements only on a short time scale. Data on particle size distribution and concentration will provide valuable information for the understanding of PM2.5 formation mechanisms, as well as source apportionment determination.

It appears worthwhile to conduct short duration intensive studies in the future that simultaneously employ a suite of particle counting instruments including the Scanning Mobility Particle Sizer (SMPS), Fast Mobility Particle Sizer (FMPS), Condensation Particle Counter (CPC), and our UPM to further evaluate the mobile component. The new NOx rule requiring the establishment of near-roadway monitors in populated areas starting in 2013 (see NO2 Section) will afford an opportunity to collocate UPMs to further investigate the mobile contribution to the overall ultrafine concentration. The recent establishment of initial regulations intended to address ultrafine particle emissions from mobile sources (LEV-3 in California, Euro V-VII in the EU) is an early indicator of more extensive regulation of ultrafine particle emissions from mobile sources expected in the future, and suggests the potential emergence of regulations for ambient ultrafine particles as well.

In our Air Pollution Microscopy laboratory, three particle characterization techniques (Laser Scanning Confocal Microscopy, Scanning Electron Microscopy, and Atomic Force Microscopy) are used to investigate the morphology of real world ultrafine particles, such as those from mobile source emissions and other industrial sources. As an example, the changes in ultrafine particle morphology resulting from the use of two strategies for reducing diesel emissions, i.e., exhaust after-treatment and the use of alternative diesel fuels were studied. These activities complement the ambient monitoring data in understanding the formation, distribution and transport of ultrafine particulate.

4.5 Sulfur Dioxide

Sulfur dioxide (SO2), a colorless, reactive gas, is produced during the burning of sulfur-containing fuels such as coal and oil, during metal smelting, and by other industrial processes. It belongs to a family of gases called sulfur oxides (SOx). Major sources include power plants, industrial boilers, petroleum refineries, smelters, iron and steel mills. Generally, the highest concentrations of sulfur dioxide are found near large fuel combustion sources.

High concentrations of SO2 can result in temporary breathing impairment for asthmatic children and adults who are active outdoors. Short-term exposures of asthmatic individuals to elevated SO2 levels while at moderate exertion may result in reduced lung function that may be accompanied by symptoms such as wheezing, chest tightness, or shortness of breath. Other effects that have been associated with longer-term exposures to high concentrations of SO2, in conjunction with high levels of PM, include respiratory illness, alterations in the lungs' defenses, and aggravation of existing cardiovascular disease. The subgroups of the population that may be affected under these conditions include individuals with cardiovascular disease or chronic lung disease, as well as children and the elderly.

Additionally, there are a variety of environmental concerns associated with high concentrations of SO2. Because SO2, along with NOx, is a major precursor to acidic deposition (acid rain), it contributes to the acidification of soils, lakes, and streams and the associated adverse impacts on ecosystems. Sulfur dioxide exposure to vegetation can increase foliar injury, decrease plant growth and yield, and decrease the number and variety of plant species in a given community. Sulfur dioxide also is a major precursor to PM2.5 (aerosols), which is of significant concern to human health, as well as a main pollutant that impairs visibility. Finally, SO2 can accelerate the corrosion of natural and man-made materials (e.g., concrete and limestone) that are used in buildings and monuments, as well as paper, iron-containing metals, zinc, and other protective coatings.

Figure 4.13 shows the number of SO2 monitors and the composite annual means in New York State over the years.

SO2 monitors and concentration trends for NYS

Figure 4.13 Sulfur Dioxide Monitors and Concentration Trends

Based on its most review of the air quality criteria for oxides of sulfur and the primary national ambient air quality standard (NAAQS) for oxides of sulfur as measured by sulfur dioxide (SO2), EPA replaced the existing 24-hour and annual standards with a new short-term standard based on the 3-year average of the 99th percentile of the yearly distribution of 1-hour daily maximum SO2 concentrations. EPA set the level of this new standard at 75 ppb, which became effective August 23, 2010. EPA is also establishing requirements for an SO2 monitoring network. These new provisions require monitors in areas where there is an increased coincidence of population and SO2 emissions. In order to do this, EPA developed a Population Weighted Emissions Index (PWEI) that uses population and emissions inventory data at the CBSA level to assign required monitoring for a given CBSA (with population and emissions being obvious relevant factors in prioritizing numbers of required monitors). The PWEI for a particular CBSA was proposed to be calculated by multiplying the population (using the latest Census Bureau estimates) of a CBSA by the total amount of SO2 emissions in that CBSA. The CBSA SO2 emission value would be in tons per year, and calculated by aggregating the county level emissions for each county in a CBSA. The PWEI values are being developed using the 2010 Census numbers. The final network design requires that any SO2 monitors required in a particular CBSA as determined based on PWEI values shall satisfy the minimum monitoring requirements if they are sited at locations where they can meet any one or more of the monitoring objectives: Source-Oriented Monitoring, Highest Concentration, Population Exposure, General Background, and Regional Transport. EPA is expected to provide additional guidance for the implementation of this rule.

There are 19 SO2 monitors in operation currently, as shown in Figure 4.14. TEI Model 43C instruments using the pulsed fluorescence method are deployed in the network.

The EPA considered setting a secondary standard for NOx and SOx that would specifically target the impact of acidic deposition on wilderness areas. The EPA ultimately decided that there was not enough information at this time to tie specific water quality thresholds with ambient air concentrations. In the July 2011 final rule for NOx and SOx, the EPA stated that they would set up a monitoring program in sensitive areas to collect information to link water quality impacts to ambient air quality measurements. The NYSDEC is participating in this pilot monitoring program in the Adirondacks. Additional monitoring equipment has been installed at several sites to determine the concentrations of gasses and particles including ammonia. These data will be used in the future to inform the next review of the NOx/SOx standard.

Map of NYS showing SO2 monitoring sites

Figure 4.14 Location Map for Sulfur Dioxide Monitoring Sites

4.6 Ozone

Ozone is a molecule made up of three oxygen atoms (O3), a very reactive gas, and even at low concentrations it is irritating and toxic. It occurs naturally in small amounts in the earth's upper atmosphere, and in the air of the lower atmosphere after a lightning storm. In the stratosphere, between 10km and 50km above the earth's surface it forms the Ozone Layer. This is an important protective layer which filters out most of the high energy ultra-violet radiation from the sun which would damage much of the life on earth. When ozone is present at ground level and in the troposphere (10-18 km above earth's surface) it is considered a pollutant and a greenhouse gas. Ozone is used both industrially and commercially due mainly to its reactivity. It is used as a clean way of purifying water both in industry and in the home in hot-tubs and fish tanks. It is also used to disinfect laundry both in hospitals and in the home.

Ground-level O3 remains a pervasive pollution problem in the United States. Ozone is readily formed in the atmosphere by the reaction of volatile organic compounds (VOCs) and NOx in the presence of heat and sunlight, which are most abundant in the summer. VOCs are emitted from a variety of sources, including motor vehicles, chemical plants, refineries, factories, consumer and commercial products, other industries, and natural (biogenic) sources. Nitrogen oxides (a precursor to ozone) are emitted from motor vehicles, power plants, and other sources of combustion, as well as natural sources including lightning and biological processes in soil. Changing weather patterns contribute to yearly differences in O3 concentrations. Ozone and the precursor pollutants that cause O3 also can be transported into an area from pollution sources located hundreds of miles upwind.

Ozone occurs naturally in the stratosphere and provides a protective layer high above the earth. However, at ground level, it is the prime ingredient of smog. Short-term (1- to 3-hour) and prolonged (6- to 8-hour) exposures to ambient O3 concentrations have been linked to a number of health effects of concern. For example, increased hospital admissions and emergency room visits for respiratory causes have been associated with ambient O3 exposures.

Exposures to O3 result in lung inflammation, aggravate preexisting respiratory diseases such as asthma, and may make people more susceptible to respiratory infection. Other health effects attributed to short-term and prolonged exposures to O3, generally while individuals are engaged in moderate or heavy exertion, include significant decreases in lung function and increased respiratory symptoms such as chest pain and cough. Children active outdoors during the summer when O3 levels are at their highest are most at risk of experiencing such effects. Other at-risk groups include adults who are active outdoors, such as outdoor workers, and individuals with preexisting respiratory disorders such as asthma and chronic obstructive lung disease. Within each of these groups are individuals who are unusually sensitive to O3. In addition, repeated long-term exposure to O3 presents the possibility of irreversible changes in the lungs, which could lead to premature aging of the lungs and/or chronic respiratory illnesses.

Ozone also affects sensitive vegetation and ecosystems. Specifically, O3 can lead to reductions in agricultural and commercial forest yields, reduced survivability of sensitive tree seedlings, and increased plant susceptibility to disease, pests, and other environmental stresses such as harsh weather. In long-lived species, these effects may become evident only after several years or even decades. As these species are out-competed by others, long-term effects on forest ecosystems and habitat quality for wildlife and endangered species become evident. Furthermore, O3 injury to the foliage of trees and other plants can decrease the aesthetic value of ornamental species as well as the natural beauty of our national parks and recreation areas.

EPA initially established primary and secondary NAAQS for photochemical oxidants on April 30, 1971. Both primary and secondary standards were set at an hourly average of 0.08 parts per million (ppm), total photochemical oxidants, not to be exceeded more than one hour per year.

On February 8, 1979, EPA completed its first periodic review of the criteria and standards for O3 and other photochemical oxidants and made significant revisions to the original standard: the level of the primary and secondary NAAQS was changed to 0.12 ppm; the indicator was changed to O3; and the form of the standards was changed to be based on the expected number of days per calendar year with a maximum hourly average concentration above 0.12 ppm (i.e., attainment of the standard occurs when that number is equal to or less than one).

In July, 1997 EPA revised the primary and secondary O3 standards on the basis of the then latest scientific evidence linking exposures to ambient O3 to adverse health and welfare effects at levels allowed by the 1-hr average standards. The O3 standards were revised by replacing the existing primary 1-hr average standard with an 8-hr average O3 standard set at a level of 0.08 ppm. The form of the primary standard was changed to the annual fourth-highest daily maximum 8-hr average concentration, averaged over three years. The secondary O3 standard was changed by making it identical in all respects to the revised primary standard. These standards were challenged in the courts and the litigation lasted until March, 2002 when the D.C. Circuit Court issued its final decision, finding the 1997 O3 NAAQS to be "neither arbitrary nor capricious," and denying the remaining petitions for review. As of June 15, 2005 EPA revoked the 1-hour ozone standard in all areas except the fourteen 8-hour ozone nonattainment Early Action Compact (EAC) Areas (none in NY).

After the most recent review of the ozone NAAQS, EPA revised the 8 hr ozone standard (primary and secondary) to 0.075 ppm, which went into effect on May 27, 2008, at which time the 1-hr standard was revoked.

The number of ozone monitors and concentration trends for both the 1 hr, and 8 hr standards in New York State for the past three decades are shown in Figures 4.15 and 4.16, respectively.

O3 monitors and one hour concentration trends for NYS

Figure 4.15 Ozone Monitors and 1 hr Concentration Trends

O3 monitors and eight hour concentration trends for NYS

Figure 4.16 Ozone Monitors and 8 hr Concentration Trends

At present NYSDEC operates 29 TEI Model 49C ozone monitors statewide, which use the UV photometric method for detection. The site locations are depicted in Figure 4.17 below.

Map of NYS showing location of ozone monitoring sites

Figure 4.17 Location Map for Ozone Monitoring Sites