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Subpart 257-5: Air Quality Standards-Photochemical Oxidants

(Statutory Authority: Environmental Conservation Law, § 15)

[Filed 2/16/77. Effective 30 days after filing.]

[This is page 1 of 1 of this Subpart. A complete list of Subparts in this regulation appears in the Chapter 3 contents page. A list of sections in this Subpart appears below.]

For administrative information about this posting, contact: Division of Air Resources. The Bureau of Air Quality Planning at (518) 402-8396 or the Bureau of Stationary Sources at (518) 402-8403 is the contact for technical questions pertaining to this rule.



§257-5.1 Definition

Photochemical oxidants are those substances in the atmosphere which are produced when reactive organic substances, principally hydrocarbons, and nitrogen oxides are exposed to sunlight. For the purpose of this Subpart, they shall include ozone, peroxyacyl nitrates, organic peroxides and other oxidants as measured by the method specified, or by an equivalent method approved by the commissioner.

§257-5.2 Objective

Photochemical oxidants cause irritation of the mucous membranes, damage to vegetation, and deterioration of materials. They affect the clearance mechanism of the lungs and later resistance to bacterial infection. The objective of these standards is to prevent such effects.

§257-5.3 Standard for all levels

In any one-hour period, the average concentration of photochemical oxidant shall not exceed 0.08 ppm1 more than once in any 12 consecutive months.


1Corresponds to Federal standard of 160 µg/m3 (at temperature of 25oC and pressure of 760 mm of mercury).

§257-5.4 Measurement

(a) Photochemical oxidant is determined by the liberation of iodine from a buffered, neutral potassium iodide solution, corrected for interferences of sulfur dioxide and oxides of nitrogen and is expressed as photochemical oxidant (ozone equivalent) per million parts of air (ppm) by volume.

(b) All measurements are corrected to a reference temperature of 24 degrees Centigrade and to a reference pressure of 760 millimeters of mercury.