FOR INCLUSION IN WYOMING STATE IMPLEMENTATION PLAN 

FROM WYOMING AIR QUALITY STANDARDS AND REGULATIONS 

Ambient Standards 

CHAPTER2 

Section 2. Ambient standards for particulate matter. 

(a) PM10: The ambient air standards for PM10 particulate matter are: 

(i) 150 micrograms per cubic meter--24-hour average concentration with 

not more than one expected exceedance per year. 

(A) Attainment of the 24-hour standard is determined in 

accordance with Appendix K of 40 CFR part 50. 

(ii) For the purpose of determining attainment of the standards, particulate 

matter shall be measured in the ambient air as PM10 (particles with an aerodynamic 

diameter less than or equal to a nominal 10 micrometers), by a reference method based on 

40 CFR part 50, Appendix J and designated in accordance with 40 CFR part 53 or an 

equivalent or alternate method designated in accordance with 40 CFR part 53. 

(b) PM2.5: The primary and secondary ambient air quality standards for PM2_5 

particulate matter are: 

(i) 15 micrograms per cubic meter (~g/m ) annual arithmetic mean 

concentration and; 

(ii) 35 micrograms per cubic meter (~g )--98 111 percentile 24-hour 

average concentration. 

(iii) Attainment of the annual and 24-hour standards is determined in 

accordance with Appendix N of 40 CFR part 50. 

(iv) For the purpose of determining attainment of the standards, 

particulate matter shall be measured in the ambient air as PM2.5 (particles with an 

aerodynamic diameter less than or equal to a nominal 2.5 micrometers), by a reference 

method based on 40 CFR part 50, Appendix L and designated in accordance with 40 CFR 

part 53 or an equivalent or alternate method designated in accordance with 40 CFR part 

53 . 

(c) Ambient air, for the area bounded by Townships 40 through 52 North, and 

Ranges 69 through 73 West, inclusive, of the Sixth Principal Meridian, Campbell and 

Converse Counties, in the Powder River Coal Basin, is defined as that portion of the 
atmosphere, external to buildings, to which the general public has access. For surface 

mining operations, the application of this definition will be limited to only those lands 

that are necessary to conduct mining operations as determined by the Administrator of 

the Wyoming Air Quality Division. 
Section 10. Ambient standards for lead. 

(a) The primary and secondary ambient air quality standards for lead (Pb) and its 

compounds are 0.15 micrograms per cubic meter, arithmetic mean concentration over a 

3-month period, measured in the ambient air as Pb either by: 

(i) A reference method based on 40 CFR part 50, Appendix G (Reference 

Method for the Determination of Lead in Suspended Particulate Matter Collected From 

Ambient Air), and designated in accordance with 40 CFR part 53 or; 

(ii) An equivalent method designated in accordance with 40 CFR part 53. 

(b) The primary and secondary ambient air quality standards for Pb are met when 

the maximum arithmetic 3-month mean concentration for a 3-year period, as determined 

in accordance with Appendix R (Interpretation ofthe National Ambient Air Quality 

Standards for Lead) of 40 CFR part 50, is less than or equal to 0.15 micrograms per cubic 

meter. 
Section 12. Incorporation by reference. 

(a) Code of Federal Regulations (CFR). All Code of Federal Regulations 

(CFRs) cited in this chapter, including their Appendices, revised and published as of July 

1, 2008, not including any later amendments, are incorporated by reference. Copies of 

the Code of Federal Regulations are available for public inspection and copies can be 

obtained at cost from the Department of Environmental Quality, Division of Air Quality, 

122 W. 25th Street, Cheyenne, Wyoming 82002. Copies ofthe CFRs can also be 

obtained at cost from Government Institutes, 15200 NBN Way, Building B, Blue Ridge 

Summit, PA 17214.