310 CMR: DEPARTMENT OF ENVIRONMENTAL PROTECTION 

Table of Con-tents 

PaRe 

310 CMR 6.00: AMBIENT AIR QUALITY STANDARDS FOR THE COMMONWEALTH OF MASSACHUSETTS 163 

Section 6.01 : Definitions 163 

Section 6.02: Scope 163 

Section 6.03: Reference Conditions 163 

Section 6.04: Standards 163 
310 CMR: DEPARTMENT OF ENVIRONMENTAL PROTECTION 

310 CMR 6.00: AMBIENT AIR QUALITY STANDARDS FOR THE COMMONWEALTH OF 

MASSACHUSETTS 

Section 

6.01: Definitions 

6.02: Scope 

6.03 : Reference Conditions 

6.04: Standards 

6.01 : Definitions 

Ambient Air means that portion of the atmosphere, external to buildings, to which the general 

public has access . 

Department means the Department of Environmental Protection. 

Equivalent method means any method of sampling and analyzing for an air pollutant which 

can be demonstrated to the Department's satisfaction to have a consistent relationship to the 

reference method. 

Reference method means a method of sampling and analyzing for an air pollutant, as 

described in the Federal Register, Volume 36, number 228, November 25, 1971 . 

6.02: Scope. 

(1) Primary ambient air quality standards define levels of air quality which the Department 

judges are necessary, with an adequate margin of safety, to. protect the public health . 

Secondary ambient air quality standards define levels of air quality which the Department 

judges necessary to protect the public welfare from any known or anticipated adverse effects 

of a pollutant. Such standards are subject to revision, and additional primary and secondary 

standards may be promulgated as the Department deems necessary to protect the public health 

and welfare. 

(2) The promulgation of primary and secondary ambient air quality standards shall not be 

considered in any manner to allow significant deterioration of existing air quality in any 

portion of the Commonwealth . 

6.03: Reference Conditions 

All measurements of air quality are corrected to a reference temperature of 25°C and to 

a reference pressure of 760 millimeters of mercury (1,013 .2 millibars) . . 

6.04: Standards 

(1) Sulfur Oxides (sulfur dioxide) . 

(a) Primary Ambient Air Quality Standards-for--Sulfur Oxides (sulfur dioxide). The 

primary ambient air quality standards for sulfur oxides, measured as sulfur dioxide by the 

reference method described in 40 CFR Part 50 or by an equivalent method, are: 

1. 80 micrograms per cubic meter (0.03 p.p .m.) annual arithmetic mean. 

2. 365 micrograms per cubic meter (0 .14 p.p.m.) Maximum 24-hour concentration 

' not to be exceeded more than once per year . 

(b) Secondary Ambient Air Quality Standards for Sulfur Oxides (sulfur dioxide) . The 

national secondary ambient sir quality standard for sulfur oxides, measured as sulfur 

dioxide by the reference method described in 40 CFR Part 50 is : 1,300 micrograms per 

cubic meter (0.5 p.p .m.) -- maximum three-hour concentration not to be exceeded more 

than once per year . 

4/1/94 310 CMR - 163 
310 CMR: DEPARTMENT OF ENVIRONMENTAL PROTECTION 

6.04: continued 

(2) Particulate Matter . 

(a) Primarv Ambient Air Quality Standards for Particulate Matter . The primary ambient air 

quality standards for particulate matter, measured by the reference method described in 

Appendix 3 of 40 CFR Part 50, or by an equivalent method, are: 

1. 50 micrograms per cubic meter annual ambient air quality standard, attained when 

the expected annual mean arithmetic concentration, as determined in accordance with 

Appendix K to 40 CFR Part 50, is less than or equal to 50 micrograms per cubic meter. 

2. 150 micrograms per cubic meter - maximum 24-hour concentration, attained when 

the expected number of days per calendar year with a 24 hour average concentration 

above 150 micro-grams per cubic meter, as determined in accordance with Appendix K 

to 40 CFR Part 50, is less than or equal to one. 

3. For purposes of determining attainment with standards, particulate matter shall be 

measured in the ambient air as PM 10 . 

(b) Secondarv Ambient Air Quality Standards for Particulate Matter. Identical to those of 

the Primary Ambient Air Quality Standards for Particulate Matter . 

(3) Primary and Secondary Ambient Air Quality Standards for Carbon Monoxide. The primary 

and secondary ambient air quality standards for carbon monoxide, measured by the reference 

method described in CFR Part 50, or by an equivalent method, are: 

(a) 10 milligrams per cubic meter (9 p.p.m.) --maximum 8-hour concentration not to be 

exceeded more than once per year. 

(b) 40 milligrams per cubic meter (35 p.p .m.) -maximum 1-hour concentration not to be 

exceeded more than once per year. 

(4) Primary and Secondary Ambient Air Quality Standards for Ozone. The primary and 

secondary ambient air quality standard for ozone, measured and corrected for interferences due 

to nitrogen oxides and sulfur dioxide by the reference method described in 40 CFR Part 50, or 

by an equivalent method, is 240 micrograms per cubic meter (0.12 ppm) - and is expressed in 

a statistical form so that determination of attainment will be made when the expected number 

of days per calendar year with maximum hourly average concentrations above 235 ug/M3 (0 .12 

ppm) is equal to less than one. 

(5) Prim= and Secondary Ambient Air Quality Standards for Nitrogen Dioxide. The primary 

and secondary ambient air quality standard for nitrogen dioxide, measured by the reference 

method described in 40 CFR Part 50, or by an equivalent method, is : 100 Micrograms per~ cubic 

meter (0 .05 p.p .m.) -- annual arithmetic mean. 

(6) Primaa and Secondarv Ambient Air Quality Standards for Lead. The primary and 

secondary -ambient air quality standard for lead measured by the reference method described in 

40 CFR Part 50, or by an equivalent method is : 1 .5 micrograms per cubic meter - calendar 

quarter. 

REGULATORY AUTHORITY 

310 CMR 6.00: M.G.L . c. 111, § 142D. 

4/26/02 (Effective 4/l/94) - corrected 310 CMR - 164