2.5 Monitoring - NYS Dept. of Environmental Conservation

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PM2.5 Monitoring

Fine Particulate Matter Monitoring

Picture depicts relative sizes of different types of particulate matter as they relate to the size of a human hair

PM is an abbreviation for particulate matter. PM2.5 is the abbreviation for fine particulate matter with a diameter smaller than 2.5 microns. (By comparison, human hair diameters range from 40 to 120 microns.) Particulate matter are tiny solid particles or liquid droplets in air. The size of particulate matter is so small, it is hard to imagine.

The picture to the left shows a human hair that has been magnified 900 to 1200 times its real size. The blue circles show how small PM10 is when compared to a human hair. The smaller orange circles inside the blue circle shows how much smaller PM2.5 particles are against a human hair. The green circles inside the orange circle show how even smaller ultrafine particles are in comparison to a human hair.

Sources of PM2.5

PM2.5 is produced by:

  • Burning petroleum-based fuels for heating buildings and powering motor vehicles
  • Chemical reactions between gases such as sulfur dioxide, nitrogen oxides, and volatile organic compounds
  • Dust from industrial activities
  • Residential wood burning, forest fires, and agricultural burning

The total amount of PM2.5 observed or forecasted for a given area forms from a combination of local and upwind sources. The emission of sulfur dioxide or other pollutants can be emitted in one region and undergo chemical reactions in the atmosphere to produce PM2.5 in another region downwind. Similarly, PM2.5 can itself travel great distances. It has been observed that large wildfires from the western part of North America have occasionally impacted air quality monitors in New York.

Health Effects of PM2.5

Adverse health effects from breathing air with a high PM2.5 concentration include:

Division of Air Resources staff performing regular maintenance on the air quality monitoring equipment located at the Queens College air monitoring site.
Division of Air Resources staff Mike Christophersen
performing regular maintenance on the air quality
monitoring equipment located at the Queens College
air monitoring site.
  • Increased respiratory symptoms and disease
  • Chronic bronchitis
  • Decreased lung function, particularly for individuals with asthma
  • Irregular heartbeat
  • Premature death in people with heart or lung disease

Public health officials caution against strenuous outdoor activity when PM2.5 levels are high. To help people decide when to curtail activity, DEC forecasts Air Quality and, in cooperation with the NYS Department of Health, posts warnings if dangerous conditions are expected to occur. These warnings are also aired through the media and are available online on our Air Quality Forecast webpage and on the toll-free New York State Air Quality Hotline at 1-800-535-1345.

Monitoring PM2.5

The EPA has promulgated health-based standards for the concentration of PM2.5 in the outdoors. The National Ambient Air Quality Standards (NAAQS) for the 24-hour average and annual average have been set at 35 and 12 micrograms (one-millionth of a gram) per cubic meter air (µg/m3), respectively. A microgram is a unit of weight. There are a million micrograms in a gram, and a pound is equal to about 450 grams.

The principal goal of the PM2.5 monitoring network is to determine the outdoor exposure of the State's population to ambient PM2.5. This 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 explicitly specified in the Code of Federal Regulations (CFR) to ensure that the measurements are consistent from one State to another. The PM2.5 FRM operates as one 24-hour sample is collected every sixth day, except for a few sites where a sample is taken every third day.

The continuous mass monitoring instruments cannot accurately provide data for direct comparison with the NAAQS, but these instruments 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. These measurements can be found on the Current Air Quality Measurement Data web page.

The NYSDEC has adjusted the PM2.5 network considering EPA expectations, updated regulations, and prioritized funding. The FRM network consisted of 40 sites when it was first established using the original design criteria from 1998. Since then the number of sites has 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 monitors required for compliance 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 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 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 wood smoke would also be exposed to higher PM2.5 concentrations than those measured at the nearest Neighborhood or Urban scale monitor.

There are also air quality monitors using this technology, modified to collect PM10 samples. PM10 is the abbreviation for fine particulate matter with a diameter smaller than 10 microns. PM10 samples from the Rochester and IS 52 Bronx sites are further analyzed to determine concentrations of selected

More information about PM2.5 and PM10 is available in the New York State Ambient Air Monitoring Program Monitoring Network Plan.

PM2.5 Monitoring Sites

Locations of sites that measure PM10 and PM2.5 and more are available on the DECinfo Locator Map. DECinfo Locator is an interactive map that lets you access DEC documents and public data about the environmental quality of specific sites in New York State, as well as outdoor recreation information. The Air Quality Monitoring Sites layer can be found under DEC Information Layers > Environmental Monitoring with the icon to the left.