Secretary of the State File Number

6157

Regulation of the

Department of Energy and Environmental 

Protection

Concerning

Ambient Air Quality Standards; Amendment 

of Sections 22a-174-24, 22a-174-1, 22a-174-3a 

and 22a-174-28

Received and filed in the Office of the

Secretary of the State on

April 7, 2014

Approved by the Attorney General on

January 14, 2014

Published in the Connecticut Law Journal on

Approved by the Legislative Regulation Review 

Committee on

April 7, 2014

Electronic copy with agency head certification statement 

submitted to the Office of the

Secretary of the State on

March 25, 2014

Effective Date

April 15, 2014

Regulations adopted after July 1, 2013, become effective 

upon posting to the website of the Secretary of the State, 

or at a later date specified within the regulation.

Website posted on

April 15, 2014
Connecticut Depa~ment of

"ENERGY &

ENVIRONMENTAL

PROTECTION

79 Elm Street  ̄ Hartford, CT 06~.06-5~.27 www,ct,gov/deep Affirmative Action/Equal Opportunity Employer

Electronic Copy Certification Statement

I, Robert J. Klee, Commissioner, of the Department of Energy and Environmental Protection, in

accordance with the provisions of Section 4-172 of the General Statutes of the State of Connecticut, do

hereby certify:

That the electronic copy of an amendment concerning Ambient Air Quality Standards, which was

approved with technical corrections and deletions by the Legislative Regulation Review Committee on

March 25, 2014, and which shall be submitted electronically for filing to the Secretary of the State by

Daniel Vesa of this agency on or before April 7, 2014, is a true and accurate copy of the amendment

approved in accordance with Sections 4-169 and 4-170 of the General Statutes of the State of

Connecticut. The technical corrections and deletions identified in the Legislative Commissioners’

Office report are reflected in the final amendment.

In testimony whereof, I have hereunto set my

hand on ~/¢

Robert J. Klee, Commissioner
REGS-1 Rev. 09/2013 Page 1 of 9

State of Connecticut

REGULATION

of the

NAME OF AGENCY:

Energy and Environmental Protection

Concerning

SUBJECT MATTER OF REGULATION:

Amendment of Sections 22a-174-24, 22a-174-1(10), 22a-174-1(88), 22a-174-

3a(k)(5) and 22a-174-28(a)(5) of the

Regulations of Connecticut State Agencies

Section 1. Subdivision (10) of section 22a-174-1 of the Regulations of Connecticut State

Agencies is revised as follows: 

(10) “AAQS” or “[Ambient] ambient air quality standard” means any standard [which] that

establishes the largest allowable concentration of a specific pollutant in the ambient air [of a 

region or subregion] as established by the [United States Environmental Protection Agency] 

Administrator in 40 CFR 50 or by the commissioner [and which is listed] in section 22a-174-24 

of the Regulations of Connecticut State Agencies.

Sec 2. Subdivision (88) of section 22a-174-1 of the Regulations of Connecticut State

Agencies is revised as follows: 

(88) “PM 10” means particulate matter with an aerodynamic diameter less than or equal to a 

nominal 10 micrometers as measured by a reference method set forth in 40 CFR 50, Appendix 

[M] J, and designated as a reference method in accordance with 40 CFR 53 or by an equivalent 

method approved by the Administrator in accordance with 40 CFR 53.

Sec. 3. Subdivision (5) of section 22a-174-3a(k) of the Regulations of Connecticut State 

Agencies is revised as follows:

(5) Ambient Monitoring

(A) The permit application shall contain an analysis of the effect on ambient air 

quality in the area of the subject source or modification, of the following 

pollutants:

(i) those that have allowable emissions in excess of the amount listed in Table 

3a(k)-1 of this subsection, or 
 Page 2 of 9

(ii) those [listed in section 22a-174-24 of the Regulations of Connecticut State 

Agencies,] for which an ambient air quality standard exists; 

(B) For any pollutant listed in Table 3a(k)-1 of this subsection for which [a National 

Ambient Air Quality Standard] an AAQS does not exist, the analysis shall contain 

such air quality monitoring data as the commissioner determines is necessary to 

assess ambient air quality for that pollutant in any area that such pollutant may 

affect;

(C) For any pollutant [(other than nonmethane hydrocarbons)] for which [a National 

Ambient Air Quality Standard] an AAQS exists, the analysis shall contain 

[continuous] air quality monitoring data approved by the commissioner and 

gathered for purposes of determining whether emissions of that pollutant would 

cause or contribute to a violation of such standard or a Prevention of Significant 

Deterioration increment listed in Table 3a(k)-2 of this subsection;

(D) The [continuous] air quality monitoring data that is required by subparagraphs (B) 

and (C) of this subdivision shall have been gathered over a period of one (1) year 

and shall represent the year preceding receipt of the application, unless the 

commissioner determines in writing that a complete and adequate analysis can be 

accomplished with monitoring data gathered over a period shorter than one (1) 

year, but not to be less than four (4) months;

(E) The owner or operator shall, after construction of the subject source or 

modification, conduct such ambient monitoring as the commissioner determines is 

necessary to determine the effect which the emissions from such source or 

modification may have, or are having, on air quality in any area. In addition, the 

owner or operator shall submit the results of such ambient monitoring to the 

commissioner within thirty (30) days of data collection; and

(F) The owner or operator shall meet the requirements of 40 CFR 58, Appendix [B] A

during the operation of monitoring.

Sec. 4. Section 22a-174-24 of the Regulations of Connecticut State Agencies is revised as 

follows:

Sec. 22a-174-24. Connecticut primary and secondary ambient air quality standards

(a) [Definitions.
 Page 3 of 9

(1) “Ambient air” means that portion of the atmosphere, external to buildings, to which the 

general public has access.

(2) “Reference method” means a method of sampling and analyzing for an air pollutant, as 

described in Title 40 Code of Federal Regulations part 50, as from time to time may be amended.

(3) “Equivalent method” means any method of sampling and analyzing for an air pollutant 

that has been designated in accordance with Title 40 of Federal Regulations part 53, as from time 

to time may be amended.

(4) “Acceptable method” means a reference method, an equivalent method, or any other 

method determined by the Commissioner.] Reserved.

(b) The concentration of pollutants in the ambient air, as measured by [an acceptable 

method] a reference or equivalent method designated in 40 CFR 50 or 40 CFR 53, shall conform 

with levels specified [below] in this section as the applicable air quality standards for these 

[substances] air pollutants throughout Connecticut. No person shall operate [a] any stationary 

source, which has a significant impact on air quality [listed in Table 3a(i)-1 set forth] as 

described in section 22a-174-3a(i)(1) of the Regulations of Connecticut State Agencies for the 

pollutants listed in Table 3a(i)-1 of section 22a-174-3a of the Regulations of Connecticut State 

Agencies, in such a manner as to cause or contribute to a violation of an ambient air quality 

standard [listed in Section 22a-174-24].

(c) [Reference conditions. All measurements of air quality are corrected to a reference 

temperature of twenty (20) degrees C. and to a reference pressure of 760 millimeters of mercury 

(1,013.2 millibars or 29.92 inches of mercury).] Reserved. 
 Page 4 of 9

(d) Connecticut primary and secondary ambient air quality standards for sulfur oxides 

(sulfur dioxide). 

(1) The level of the Connecticut primary 1-hour ambient air quality [standards] standard for 

sulfur oxides, measured as sulfur dioxide, [are:

(1) 80 micrograms per cubic meter (0.03 ppm) -- annual arithmetic mean.

(2) 365 micrograms per cubic meter (0.14 ppm) -- maximum 24-hour concentration not to be 

exceeded more than once per year.] is 75 parts per billion, as set out in 40 CFR 50.17. 

(2) The level of the Connecticut primary 24-hour ambient air quality standard for sulfur 

oxides, measured as sulfur dioxide, is 0.14 parts per million, as set out in 40 CFR 50.4.

(3) The level of the Connecticut primary annual ambient air quality standard for sulfur 

oxides, measured as sulfur dioxide, is 0.030 parts per million, as set out in 40 CFR 50.4.

(4) The level of the Connecticut secondary 3-hour ambient air quality standard for sulfur 

oxides, measured as sulfur dioxide, is 0.5 parts per million, as set out in 40 CFR 50.5. 

(e) [Connecticut secondary ambient air quality standards for sulfur oxides (sulfur 

dioxide). The Connecticut secondary ambient air quality standard for sulfur oxides, measured as 

sulfur dioxide, is:

(1) 1,300 micrograms per cubic meter (0.5 ppm) -- maximum 3-hour concentration not to be 

exceeded more than once per year.

(2) 260 micrograms per cubic meter (0.1 ppm) -- maximum 24-hour concentration not to be 

exceeded more than once per year.

(3) 1,300 micrograms per cubic meter (0.5 ppm) -- maximum 3-hour concentration not to be 

exceeded more than once per year.]

Connecticut primary and secondary ambient air quality standards for PM 10. 

The level of the Connecticut primary and secondary 24-hour ambient air quality standards for 

particulate matter, measured as PM 10, is 150 micrograms per cubic meter, as set out in 40 CFR 

50.6.
 Page 5 of 9

(f) Connecticut primary and secondary ambient air quality standards for PM 2.5 (fine

particulate matter).

(1) [The level of the Connecticut primary 24-hour ambient air quality standard for particulate 

matter, measured as PM10, is 150 micrograms per cubic meter (ug/m3), 24-hour average 

concentration. The standard is attained when the expected number of days per calendar year with 

a 24-hour average concentration above 150 (ug/m3), as determined in accordance with Appendix 

K of Title 40 Code of Federal Regulations Part 50 revised as of July 1, 1989, is equal to or less 

than one.] The level of the Connecticut primary annual ambient air quality standard for fine 

particulate matter, measured as PM 2.5, is 12.0 micrograms per cubic meter, as set out in 40 CFR 

50.18.

(2) [The level of the Connecticut primary annual standard for particulate matter, measured 

as PM10, is 50 micrograms per cubic meter (ug/m3), annual arithmetic mean. The standard is 

attained when the expected annual arithmetic mean concentration, as determined in accordance 

with Appendix K of Title 40 Code of Federal Regulations Part 50 revised as of July 1, 1989, is 

equal to or less than 50 (ug/m3).] The level of the Connecticut secondary annual ambient air 

quality standard for fine particulate matter, measured as PM 2.5, is 15.0 micrograms per cubic 

meter, as set out in 40 CFR 50.13.

(3) The level of the Connecticut primary and secondary 24-hour ambient air quality 

standards for fine particulate matter, measured as PM 2.5, is 35 micrograms per cubic meter, as 

set out in 40 CFR 50.18 and 40 CFR 50.13, respectively.

(g) [Connecticut secondary ambient air quality standards for particulate matter

(1) The level of the Connecticut secondary 24-hour ambient air quality standard for 

particulate matter, measured as PM10, is 150 micrograms per cubic meter (ug/m3), 24-hour 

average concentration. The standard is attained when the expected number of days per calendar 

year with a 24- hour average concentration above 150 (ug/m3), as determined in accordance with 

Appendix K of Title 40 Code of Federal Regulations Part 50 revised as of July 1, 1989, is equal 

to or less than one.

(2) The level of the Connecticut secondary annual standard for particulate matter, measured 

as PM10, is 50 micrograms per cubic meter (ug/m3), annual arithmetic mean. The standard is 

attained when the expected annual arithmetic mean concentration, as determined in accordance 

with Appendix K of Title 40 Code of Federal Regulations Part 50 revised as of July 1, 1989, is 

equal to or less than 50 (ug/m3).] Reserved. 
 Page 6 of 9

(h) Connecticut primary [and secondary] ambient air quality standards for carbon 

monoxide. [The Connecticut primary and secondary ambient air quality standards for carbon 

monoxide, are:] The levels of the Connecticut primary ambient air quality standards for carbon 

monoxide, as set out in 40 CFR 50.8, are as follows: 

(1) [10 milligrams per cubic meter (9 ppm) -- maximum 8-hour concentration not to be 

exceeded more than once per year.] 9 parts per million for an 8-hour average concentration; and

(2) [40 milligrams per cubic meter (35 ppm) -- maximum 1- hour concentration not to be 

exceeded more than once per year.] 35 parts per million for a 1-hour average concentration. 

(i) Connecticut primary and secondary ambient air quality standards for ozone.

[(1) Connecticut 8-hour primary and secondary ambient air quality standards 

for ozone.

(A) The level of the Connecticut 8-hour primary and secondary ambient air quality 

standards for ozone is 0.08 parts per million, daily maximum 8-hour average, 

measured by a reference method based on 40 CFR 50, Appendix D.

(B) The Connecticut 8-hour primary and secondary ambient air quality standards are 

met at an ambient air quality monitoring site when the average of the annual 

fourth-highest daily maximum 8-hour average ozone concentration is less than or 

equal to 0.08 parts per million, as determined in accordance with 40 CFR 50, 

Appendix I.

(2) Connecticut 1-hour primary and secondary ambient air quality standards 

for ozone.

(A) The level of the Connecticut 1-hour primary and secondary ambient air quality 

standards for ozone is 0.12 parts per million (235 μg/m3), measured by a 

reference method based on 40 CFR 50, Appendix D. 

(B) The Connecticut 1-hour primary and secondary ambient air quality standards are 

met when the expected number of days per calendar year with maximum hourly 

average concentrations above 0.12 parts per million is equal to or less than one 

day, as determined by 40 CFR 50, Appendix H.] 

(1) The level of the Connecticut 8-hour primary and secondary ambient air quality standards 

for ozone, measured by a reference method based on Appendix D of CFR 50.10 and designated 

in accordance with 40 CFR 53, is 0.08 parts per million, as set out in 40 CFR 50.10.
 Page 7 of 9

(2) The level of the Connecticut 8-hour primary and secondary ambient air quality standards 

for ozone is 0.075 parts per million, daily maximum 8-hr average, as set out in 40 CFR 50.15. 

(j) [Connecticut primary and secondary ambient air quality standards for

hydrocarbons. The hydrocarbons standard is for use as a guide in achieving oxidant standards. 

The Connecticut primary and secondary ambient air quality standard for hydrocarbons is: 160 

micrograms per cubic meter (0.24 ppm) -- maximum 3-hour concentration (6 am to 9 am) not to 

be exceeded more than once per year.] Reserved. 

(k) Connecticut primary and secondary ambient air quality standards for [nitrogen 

dioxide] oxides of nitrogen (nitrogen dioxide). [The Connecticut primary and secondary 

ambient air quality standard for nitrogen dioxide, is: 100 micrograms per cubic meter (0.05 ppm) 

-- annual arithmetic mean.]

(1) The level of the Connecticut primary and secondary annual ambient air quality standard 

for oxides of nitrogen, measured as nitrogen dioxide, is 53 parts per billion, as set out in 40 CFR 

50.11. 

(2) The level of the Connecticut primary 1-hour ambient air quality standard for oxides of 

nitrogen, measured as nitrogen dioxide, is 100 parts per billion, as set out in 40 CFR 50.11.

(l) Connecticut primary and secondary ambient air quality standards for lead. 

The Connecticut primary and secondary ambient air quality [standard] standards for lead and its 

compounds[, measured as elemental lead is: 1.5 micrograms per cubic meter, maximum 

arithmetic mean averaged over three consecutive calendar months.] are 0.15 micrograms per 

cubic meter, as set out in 40 CFR 50.16. 

(m) Connecticut primary ambient air quality standard for dioxin. The Connecticut 

primary ambient air quality standard for dioxin is 1.0 picograms per cubic meter annual average. 

For the purposes of determining compliance with this standard the commissioner may use a 

concentration of 7.0 picograms per cubic meter 8-hour average. [Within three years of the 

effective date of this subsection, the commissioner shall refer this standard for review and 

comment by the hazardous air pollutant advisory panel.]

Sec. 5. Section 22a-174-28(a)(5) of the Regulations of Connecticut State Agencies is revised 

as follows:

(5) “Control period” means the period from November 1 to the last day of February for the 

Central Control Area and the Southwestern Control Area if a violation of the ambient air quality 
 Page 8 of 9

standard for carbon monoxide, [as listed in subsection 22a-174-24(h) of the Regulations of 

Connecticut State Agencies] as determined in accordance with the procedures specified in [Title 

40 Code of Federal Regulations Part 50] 40 CFR 50, occurs within such Control Area after 

November 1, 1998. If such violation occurs between December 1 and September 1, the Control 

Period for the Control Area in which such violation occurred begins the following November. If 

such violation occurs between September 1 and December 1, the Control Period for the Control 

Area in which such violation occurred begins sixty (60) days after such violation for the initial 

Control Period and begins November 1 for each succeeding year.

Statement of purpose: 

The purpose of this proposal is to update the Department’s ambient air quality standards as 

required by the U.S. Environmental Protection Agency (EPA). EPA has established ambient air 

quality standards for each of six criteria pollutants at levels necessary to protect public health 

with an adequate margin of safety. EPA reviews each standard on a five-year cycle and updates 

the standard if warranted by the latest science. As the Department has not revisited the 

Connecticut air quality standards in a number of years, many standards require a change in the 

level of the standard in Connecticut’s regulation.

The proposal also clarifies that the ambient air quality standards are relevant to emissions from 

stationary sources regardless of whether the source is subject to an individual air quality permit 

or not. As some of the sources without permits are old and high emitting, a prohibition on 

individual source emissions in relation to an ambient air quality standard is a useful enforcement 

tool, particularly as many of the newer ambient standards look at emissions over a short period 

of time, such as a day or an hour. 

As the federal ambient air quality standards apply to Connecticut independently, Connecticut’s 

air is judged against the most current and strict federal standards. Thus, the legal effect of these 

changes is consistency between state and federal ambient air quality standards, which is an 

element required by EPA before EPA may fully approve Connecticut’s State Implementation 

Plan as sufficient for the regulation of recently adopted federal standards. 
REGS-1 Rev. 09/2013 Page 9 of 9

CERTIFICATION

e)hereby certify that the above Regulation(s). is/are (check all that apply) [] adopted [] amended [] repealed by this agency pursuant to the following authority (ies): (cornp/ete

a//that apply)

a. Connecticut General Stafutes section(s) 22a-174, 22a-198.

b. Public Act Number(s) __

And I further certify  ̄

2) that Notice of intent to adopt, amend, or repeal ssid regulation(s) was electronically submitted to the Secretary of the State on 8/28/13,

and posted to the Secretary’s regulations website on_8/29/! 31

3) and that a public hearing regarding the proposed regulation(s) was held on 10/9113 or [] that no public hearing was held;

4) and that notice of Decision to Take Action on said regulations was electronice{ly submitted to the Secretary of the State on~

201~4, and posted to the Secretary’s regulations website on ;

5) and that said regulation(s) is/are EFFECTIVE

]When posted online by the Secretary of the State.

OR [] on (inse~date)__,

6) SIGNED(HeadofBoard,:A~encyorC,,~rn~ssi~n) ’ OFFIC~LTITLE, DUL~AUTHORIZED ~ DATE

APPROVED by the A~o~ey G~n~ral asia legal su~ciency in accoMance with CGS Section 4-169, as amended

DATE J SIGNED [~ey~#%eralorAe’sdestgnatedrepresentative) OFFIC~L TITLE, DULYAUTHORIZED

Proposed regulations am DEEMED APPRO~E~ ~y the A#o~ey General in a~ordance with COS Section 4-169, as amended, if the A#omey General

s to give notice to the agency of any/ega~u~ciency within thi~ (30) days of the receipt of the proposed regulation.

(For Regulation Review Commi~ee Use ONL

]DEEMED APPROVED, pursuant to CGS 4-170(c), as amended.

r--] Rejected without Prejudice [] Disapproved, pursuant to CGS 4-170(c), as amended.

By the Legislative Regulation Review DATE ~egulalionRevtew Committee)

Committee in accordance with CGS Section 4-i o, as amended &bl fl

In accordance with CGS Section 4-172, as amended by PA 13.247 and PA 13-274, one ce~ti~d paper copy and one electronic copy

with agency head certification statement received on the data(s~ecified below.

DATE SIGNED (Secretary of the State) I BY

I

(For Secretary of the State Use ONLY)

Date Posted to SOTS Regulations Website:

Date Electronic Copy Forwarded to the

Commission on Official Legal Publications:

SOTS file stamp: