1

To: US EPA OAQPS 

From: SRA International, Inc.

Subject: Summary of State NOx Regulations for Selected Stationary Sources 

Date: September 30, 2014

SRA compiled a summary of state/local NOx emission control regulations pertaining six categories of 

nonEGUs: 

 Cement kilns

 Industrial/Commercial/Institutional (ICI) Boilers – Coal-fired

 ICI Boilers – Gas-fired

 ICI Boilers – Oil-fired

 Gas Turbines

 Internal Combustion (IC) Engines

The analysis included 27 states in the eastern two-thirds of the U.S. For each of these states and source 

categories, we identified state-specific sub-categories (e.g. fuel type or size threshold), the NOx emission 

limit or control requirement, averaging time for the emission limit, geographic applicability within the 

state, testing/monitoring requirements, and rule citation. This information is contained in the attached 

spreadsheet (Draft State NOx RACT Limits 2014_04_01.xlsx).

Attachment 1 is an overall summary of the relative stringency of the NOx requirements by geographic 

area and source category. We also prepared a 2-page summary for each of the six categories to concisely 

compare state NOx emission limits or control requirements. These are shown in Attachments 2 to 7, along 

with notes highlighting the major differences between the state regulations.

Please let us know should you have questions or comments about any of the data presented in this 

memorandum. 
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Attachment 1 – Relative Stringency of NOx Requirements

Source Category States/Areas with 

Most Stringent Regulations

States/Areas with 

Less Stringent Regulations

States with 

No Regulations or Sources

Cement Kilns1States: IL, MD, NY, PA, TX

Areas: Ellis County, TX

States: AL (NOx SIP area), IN, KY, 

MO, MI, OH, SC, TN, VA, WV

States: AR, FL, GA, MS, OK

States with no cement kilns: 

CT, DE, LA, MA, NC, NJ, WI

Coal-fired ICI Boilers2States: NY

Areas: Chicago, St. Louis (IL portion), 

Baton Rouge, Houston-Galveston (cokefired), Milwaukee,

States: FL, GA, IN, MA, MD, MI, PA, 

TN, VA

Areas: Chicago, St. Louis (MO 

portion), Baton Rouge, Charlotte, 

Cleveland

States: AL, AR, KY, MS, OK, SC, TX 

(except Houston-Galveston) WV

NE States with no coal-fired ICI 

boilers: CT, DE, NJ

Gas-fired ICI Boilers States: NJ, NY, PA

Areas: Chicago, St. Louis (IL portion), 

Baton Rouge, Beaumont-Port Arthur, 

Cleveland, Dallas, Houston, Milwaukee

States: CT, DE, FL,GA, MA, MD, MI, 

MO, TN, VA

Areas: Clark/Floyd Counties, St. 

Louis (MO portion), Charlotte 

States: AL, AR, KY, MS, OK, SC, WV

Oil-fired ICI Boilers States: NJ, NY, PA

Areas: Chicago, St. Louis (IL portion), 

Baton Rouge, Cleveland, Dallas, Houston, 

Milwaukee

States: CT, DE, FL, GA, MA, MD, 

MI, TN, VA

Areas: Clark/Floyd Counties, St. 

Louis (MO portion), Charlotte

States: AL, AR, KY, MS, OK, SC, WV

Gas Turbines States: NJ 

Areas: GA 45-county area, Dallas, 

Houston, Milwaukee

States: CT, DE, FL, LA, MA, MD, 

NY, PA, TN, VA

Areas: Chicago, St. Louis (IL 

portion), St. Louis (MO portion), 

Charlotte, Cleveland, 

States: AL, AR, IN, KY, MI, MS, OK, 

SC, WV

IC Engines > about 500 hp States: MD, NJ, NY

Areas: Chicago, St. Louis (IL portion), 

Dallas, Houston

States: CT, DE, MA, MI, PA, TN, VA

Areas: Baton Rouge, St. Louis (MO 

portion), Charlotte, Cleveland, 

Milwaukee

States: AL, AR, IN, KY, MS, OK, SC, 

WV

1) Cement kiln emission limits imposed by recent EPA enforcement settlements tend to be more stringent than the emission control 

requirements in state rules.

2) CT, DE and NJ have no active coal-fired boilers, so the stringency of their regulations for coal-fired ICI boilers is difficult to evaluate 
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Attachment 2 - Cement Kilns

NOx Limit (lbs/ton clinker)

State Long Dry Long Wet Pre-heater Pre-calciner

AL Ozone season: low-NOx burners, mid-kiln system firing, or approved ACT 

AR No Limits No Limits No Limits No Limits

CT No Cement Kilns in State

DE No Cement Kilns in State

FL No Limits No Limits No Limits No Limits

GA No Limits No Limits No Limits No Limits

IL 5.1 5.1 3.8 2.8

IN 6.0 5.1 3.8 2.8

IN

(Clark/Floyd)

10.8 (op day)/

6 (30 day)

No Limits 5.9 (op day)/

4.4 (30 day)

No Limits

KY 6.6 6.6 6.6 6.6

LA No Cement Kilns in State

MA No Cement Kilns in State

MD 5.1 6.0 2.8 2.8

MI 6.0 5.1 3.8 2.8

MO 6.0 6.8 4.1 2.7

MS No Limits No Limits No Limits No Limits

NC No Cement Kilns in State

NJ No Cement Kilns in State

NY Case-by-case RACT Determination 

OH Ozone season: low-NOx burners, mid-kiln system firing, or approved ACT 

OK No Limits No Limits No Limits No Limits

PA 3.44* 3.88* 2.36* 2.36*

SC Ozone season: low-NOx burners, mid-kiln system firing, or approved ACT 

TN Ozone season: low-NOx burners, mid-kiln system firing, or approved ACT 

TX 5.1 4 3.8 2.8

TX

(Ellis County)

No Limits 3.4 No Limits 1.7

VA Case-by-case RACT Determination 

WI No Cement Kilns in State

WV Ozone season: low-NOx burners, mid-kiln system firing, or approved ACT 

ACT = Alternative Control Technology 

* Pennsylvania has proposed “RACT 2” presumptive RACT limits 
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Observations Regarding State NOx Rules for Cement Kilns:

 Geographic Applicability

 All NOx SIP Call states with cement kilns have NOx rules in place 

 Since only portions of Alabama, Michigan, and Missouri were affected by NOx SIP Call, the 

NOx rules only apply in the affected counties.

 States not included in the NOx SIP Call do not have NOx RACT for cement kilns, except for 

Texas. The Texas NOx requirements only apply in in Bexar, Comal, Ellis, Hays, and McLennan 

Counties.

 Form of NOx Limitation or Control Requirement

 A few states express the requirement as “at least one of the following: low-NOx burners, mid-kiln 

system firing, alternative control techniques or reasonably available control technology approved 

by the Director and the EPA as achieving at least the same emissions decreases as with low-NOX 

burners or mid-kiln system firing.”

 A few states specify presumptive emission limits in terms of pounds of NOx per ton of clinker.

 Three states do not set presumptive emission limits but rather require facilities to submit a caseby-case RACT determination. Pennsylvania has a proposed regulation that will specify 

presumptive RACT limits; current rules require sources to hold 1 trading allowance per ton of 

NOx calculated by multiplying tons clinker by the presumptive NOx limit. 

 Stringency of NOx Limitation or Control Requirement

 For states requiring “low-NOX burners, mid-kiln system firing, or ACT”, it is generally assumed 

that this will result in a 30% reduction from uncontrolled levels. 

 For states with numerical emission limits, the limits generally represent a 20 – 40 % reduction 

from uncontrolled levels, depending on the type of kiln.

 Texas has very stringent limits for kilns in Ellis County.

 Pennsylvania has proposed presumptive RACT emission limitations in April 2014 that are more 

stringent than existing presumptive RACT limits in other states. 
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Attachment 3 – Coal-fired Boilers

NOx Limit (lbs/mmBtu)

State Geographic Area

Boilers

50-100 

mmBtu/hr

Boilers

100 - 250 

mmBtu/hr

Boilers

>250 

mmBtu/hr

AL Statewide No limits No limits No limits

AR Statewide No limits No limits No limits

CT Statewide 0.29 to 0.43 0.29 to 0.43 0.29 to 0.43

DE Statewide LEA, Low NOx, 

FGR

0.38 to 0.43 0.38 to 0.43

FL Broward, Dade, Palm Beach 

Counties

0.9 0.9 0.9

GA 45 county area No limits 30 ppmvd @ 3% 

O2

0.7

IL Chicago & St Louis areas Tune-up 0.12 CFB

0.25 Other

0.12 CFB

0.18 Other

IN Clark and Floyd Counties No limits 0.4 to 0.5 0.4 to 0.5 

KY Statewide No limits No limits No limits

LA Baton Rouge 5 counties & 

Region of Influence

0.2 0.1 0.1

MA Statewide 0.43 0.33 to 0.45 0.33 to 0.45

MD Select counties No limits 0.38 to 1.0 0.38 to 1.0

MI Fine grid zone No limits No limits 0.4

MO St Louis area No limits 0.45 to 0.86 0.45 to 0.86

MS Statewide No limits No limits No limits

NC Charlotte 6 county area No limits 0.4 to 0.5 1.8

NJ Statewide 0.43 to 1.0 0.38 to 1.0 0.38 to 1.0

NY Statewide No limits 0.08 to 0.20 0.08 to 0.20

OH Cleveland 8 county area 0.3 0.3 0.3

OK Statewide No limits No limits No limits

PA Statewide 0.45 0.45 0.20 to 0.35

SC Statewide No limits No limits NOx SIP Call

TN 5 Counties Source specific 

RACT

Source specific 

RACT

Source specific 

RACT

TX Houston area 0.057

coke-fired

0.057

coke-fired

0.057

coke-fired

VA Northern VA No limits 0.38 to 1.0 0.38 to 1.0

WI Milwaukee 7 county area 0.10 to 0.25 0.10 to 0.25 0.10 to 0.20

WV Statewide No limits No limits No limits
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Observations Regarding State NOx Rules for Coal-fired Boilers:

 Geographic Applicability

 States in the OTR (CT, DE, MA, MD, NJ, NY, and PA) have NOx emission requirements that 

apply statewide, not just in ozone nonattainment areas. 

 Six states (AL, AR, KY, MS, OK, and WV) do not have regulations limiting NOx emissions.

 For the remaining states (FL, GA, IL, IN, KY, LA, MI, MO, NC, OH, TN, VA, WI), the NOx 

emission control requirements only apply in ozone nonattainment areas.

 Texas only has emission limitations for coke-fired boilers in the Houston-Galveston 

nonattainment area.

 Size Applicability

 Most of the states do not have NOx emission requirements for boilers less than 100 mmBtu/hour.

 10 states do regulation boilers in the 50-100 mmBtu size range.

 Form of NOx Limitation or Control Requirement

 Nearly all states express the NOx emission limits in terms of lbs/mmBtu.

 A few states require either a case-by-case RACT determination or specify specific types of 

control equipment (e.g., low-NOx burners, flue gas recirculation).

 Stringency of NOx Limitation or Control Requirement

 Most states specify different emission limits for different types of boilers and firing types (e.g., 

dry bottom tangential-fired) vs. dry bottom wall-fired)

 A few states in the Northeast have very few or no coal-fired ICI boilers, so the stringency of the 

regulations in those states is difficult to evaluate. These states are CT, DE, NJ and MA. 

 For boilers greater than 100 mmBtu/hour, the LADCO/OTC1 Phase I recommended limits are in 

the 0.2-0.3 lbs/mmBtu range (depending on boiler/firing configuration). The LADCO/OTC Phase 

II recommended limits are in the 0.1-0.2 lbs/mmBtu range. Four areas have limits that generally 

meet the LADCO/OTC recommendations (Chicago, Baton Rouge, New York State, and 

Milwaukee. 

 Texas has a very stringent limit (0.057 lbs/mmBtu) for coke-fired boilers in the HoustonGalveston area.

 

1 Evaluation of Control Options for Industrial, Commercial and Institutional (ICI) Boilers Technical Support 

Document (TSD), March, 2011 prepared by the Lake Michigan Air Directors Consortium (LADCO) and the Ozone 

Transport Commission (OTC).
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Attachment 4 – Gas-fired Boilers

NOx Limit (lbs/mmBtu)

State Geographic Area

Boilers

50-100 

mmBtu/hr

Boilers

100 - 250

mmBtu/hr

Boilers

>250

mmBtu/hr

AL Statewide No Limits No Limits No Limits

AR Statewide No Limits No Limits No Limits

CT Statewide 0.2 to 0.43 0.2 to 0.43 0.2 to 0.43

DE Statewide LEA, low NOx, FGR 0.2 0.2

FL Broward, Dade, Palm Beach 

Counties 0.2 to 0.5 0.2 to 0.5 0.2 to 0.5

GA 45 county area 30 ppmvd 

@ 3% O2

30 ppmvd 

@ 3% O2 0.2

IL Chicago & St. Louis Areas Tune-up 0.08 0.08

IN Clark and Floyd Counties No Limits 0.2 0.2

KY Statewide No Limits No Limits No Limits

LA Baton Rouge 5 counties & 

Region of Influence 0.1 to 0.2 0.1 0.1

MA Statewide 0.1 0.2 0.2 to 0.28

MD Select counties Tune-up 0.2 0.2

MI Fine grid zone No limits Source specific 

RACT 0.2

MO St Louis area No limits 0.2 to 0.5 0.2 to 0.5

MS Statewide No limits No limits No Limits

NC Charlotte 6 county area 0.3 0.3 0.3

NJ Statewide 0.1 to 0.5 0.1 0.1

NY Statewide 0.05 0.06 0.08

OH Cleveland 8 county area 0.1 0.1 0.1

OK Statewide No limits No limits No limits

PA Statewide 0.08 0.08 0.08

SC Statewide No limits No limits No Limits

TN 5 Counties Source specific 

RACT

Source specific 

RACT

Source specific 

RACT

TX Dallas and Houston areas 0.03 or 

90% reduction

0.03 or 

90% reduction

0.03 or 

90% reduction

TX Beaumont area 0.10 0.10 0.10

VA Northern VA 0.2 0.2 0.2

WI Milwaukee 7 county area No limits 0.08 0.08

WV Statewide No limits No limits No Limits
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Observations Regarding State NOx Rules for Gas-fired Boilers:

 Geographic Applicability

 States in the OTR (CT, DE, MA, MD, NJ, NY, and PA) have NOx emission requirements that 

apply statewide, not just in ozone nonattainment areas. 

 Six states (AL, AR, KY, MS, OK, and WV) do not have regulations limiting NOx emissions.

 For the remaining states (FL, GA, IL, IN, KY, LA, MI, MO, NC, OH, TN, TX,VA, WI), the NOx 

emission control requirements only apply in ozone nonattainment areas. 

 Size Applicability

 About half of the states have NOx emission requirements for boilers less than 100 mmBtu/hour, 

ranging from combustion tuning to emission limits as low as 0.05 lbs/mmBtu.

 Form of NOx Limitation or Control Requirement

 Nearly all states express the NOx emission limits in terms of lbs/mmBtu.

 A few states require either a case-by-case RACT determination or specify specific types of 

control equipment (e.g., low-NOx burners, flue gas recirculation).

 Stringency of NOx Limitation or Control Requirement

 The LADCO/OTC Phase I recommendations are combustion tuning for boilers less than 100 

mmBtu/hour, and either 0.1 lbs/mmBtu or 50% reduction for boilers greater than 100 mmBtu/hr. 

 The LADCO/OTC Phase II recommendations are either 0.05-0.1 lbs/mmBtu or 60% reduction.

 New Jersey and New York have state-wide limits that are consistent with the OTC/LADCO 

Phase II recommendations. Pennsylvania has proposed state-wide limits that are consistent with 

the OTC/LADCO Phase II recommendations.

 Five areas (Chicago, Baton Rouge, Beaumont-Port Arthur, Cleveland, and Milwaukee) have 

limits that are consistent with the OTC/LADCO Phase II recommendations. 

 Dallas and Houston have the most stringent emission limitations – 0.02 lbs/mmBtu for greater 

that 100 mmBtu/hr units.
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Attachment 5 – Oil-fired Boilers

NOx Limit (lbs/mmBtu)

State Geographic Area

Boilers

50-100 

mmBtu/hr

Boilers

100 - 250 

mmBtu/hr

Boilers

>250 

mmBtu/hr

AL Statewide No limits No limits No limits

AR Statewide No limits No limits No limits

CT Statewide 0.2 Distillate

0.25-0.43 Resid.

0.2 Distillate

0.25-0.43 Resid.

0.2 Distillate

0.25-0.43 Resid.

DE Statewide LEA, Low NOx, FGR 0.38 to 0.43 0.38 to 0.43

GA 45 county area 30 ppmvd 30 ppmvd 0.3

IL Chicago & St Louis areas Tune-up 0.1 Distillate

0.15 Resid.

0.1 Distillate

0.15 Resid.

IN Clark and Floyd Counties No limits 0.2 Distillate

0.3 Resid.

0.2 Distillate

0.3 Resid.

KY Statewide No limits No limits NOx SIP Call

LA Baton Rouge 0.2 0.1 0.1

MA Statewide Tune-up 0.3 Distillate

0.4 Resid.

0.25 to 0.28

MD Select counties No limits 0.25 0.25

MI Fine grid zone No limits No limits 0.3 Distillate

0.4 Residual

MO St Louis area No limits 0.3 0.3

MS Statewide No limits No limits No limits

NC Charlotte 6 county area 0.2 0.2 0.2

NJ Statewide Tune-up 0.1 Distillate

0.2 Resid.

0.1 Distillate

0.2 Resid.

NY Statewide 0.08 to 0.2 0.15 0.15 to 0.2

OH Cleveland 8 county area 0.12 Distillate

0.23 Resid.

0.12 Distillate

0.23 Resid.

0.12 Distillate

0.23 Resid.

OK Statewide New only New only New only

PA Statewide 0.12 Distillate

0.20 Resid.

0.12 Distillate

0.20 Resid.

0.12 Distillate

0.20 Resid.

SC Statewide No limits No limits No limits

TN 5 Counties Case-by-Case 

RACT

Case-by-Case 

RACT

Case-by-Case 

RACT

TX Dallas and Houston areas No limits ~0.01 ~0.01

VA Northern VA 0.25 to 0.43 0.25 to 0.43 0.25 to 0.43

WI Milwaukee 7 county area No limits 0.10 Distillate

0.15 Resid.

0.10 Distillate

0.15 Resid.

WV Statewide No limits No limits No limits
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Observations Regarding State NOx Rules for Oil-fired Boilers:

 Geographic Applicability

 States in the OTR (CT, DE, MA, MD, NJ, NY, and PA) have NOx emission requirements that 

apply statewide, not just in ozone nonattainment areas. 

 Six states (AL, AR, MS, OK, SC, and WV) do not have regulations limiting NOx emissions.

 For the remaining states (FL, GA, IL, IN, KY, LA, MI, MO, NC, OH, TN, TX, VA, WI), the 

NOx emission control requirements only apply in ozone nonattainment areas. 

 Size Applicability

 About half of the states have NOx emission requirements for boilers less than 100 mmBtu/hour, 

ranging from combustion tuning to emission limits as low as 0.08 lbs/mmBtu.

 Form of NOx Limitation or Control Requirement

 Nearly all states express the NOx emission limits in terms of lbs/mmBtu.

 A few states require either a case-by-case RACT determination or specify specific types of 

control equipment (e.g., low-NOx burners, flue gas recirculation).

 Stringency of NOx Limitation or Control Requirement

 The LADCO/OTC Phase I recommendations for distillate oil are combustion tuning for boilers 

less than 100 mmBtu/hour, and either 0.1 lbs/mmBtu or 50% reduction for boilers greater than 

100 mmBtu/hr. The LADCO/OTC Phase II recommendations for distillate oil are either 0.08-0.1 

lbs/mmBtu or 60% reduction.

 Only New Jersey has state-wide limits that are consistent with the OTC/LADCO Phase II 

recommendations for distillate oil. 

 Three areas (Chicago, Baton Rouge, and Milwaukee) have limits that are consistent with the 

OTC/LADCO Phase II recommendations for distillate oil. 

 The LADCO/OTC Phase I recommendations for residual oil are combustion tuning for boilers 

less than 100 mmBtu/hour, and either 0.2 lbs/mmBtu or 60% reduction for boilers greater than 

100 mmBtu/hr. The LADCO/OTC Phase II recommendations for residual oil are either 0.2 

lbs/mmBtu or 50-70% reduction.

 New Jersey and New York have state-wide limits that are consistent with the OTC/LADCO 

Phase II recommendations for residual oil. Pennsylvania has proposed state-wide limits that are 

consistent with the OTC/LADCO Phase II recommendations for residual oil. 

 Four areas (Chicago, Baton Rouge, Charlotte, and Milwaukee) have limits that are consistent with 

the OTC/LADCO Phase II recommendations for residual oil 

 Dallas and Houston have the most stringent emission limitations – 0.01 lbs/mmBtu for greater 

that 100 mmBtu/hr units.
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Attachment 6 – Gas Turbines 

NOx Limit (ppmvd @15% O2)

State Geographic Area

Simple Cycle

>25 MW

Gas-fired

Simple Cycle

>25 MW

Oil-fired

Combined Cycle

> 25 MW

Gas-fired

Combined Cycle

> 25 MW

Oil-fired

AL Fine grid zone No limits No limits No limits No limits

AR Statewide No limits No limits No limits No limits

CT Statewide 55 258

(0.9 lb/mmBtu)

55 258

(0.9 lb/mmBtu)

DE Statewide 42 88 42 88

GA 45 county area 6 6 6 6

IL Chicago & St Louis 

areas

42 96 42 96

IN Statewide No limits No limits No limits No limits

KY Statewide No limits No limits No limits No limits

LA Baton Rouge 5 

counties & Region 

of Influence

54

(0.2 lb/mmBtu)

86

(0.3 lb/mmBtu)

54

(0.2 lb/mmBtu)

86

(0.3 lb/mmBtu)

MA Statewide 65 100 42 65

MD Select counties 42 65 42 65

MI Fine grid zone No limits No limits No limits No limits

MO St Louis area 75 100 75 100

MS Statewide No limits No limits No limits No limits

NC Charlotte 6 county 

area

75 95 75 95

NJ Statewide 33

(2.2 lb/MWh)

53

(3.0 lb/MWh)

33

(2.2 lb/MWh)

53

(3.0 lb/MWh)

NY Statewide 50 100 42 65

OH Cleveland 8 county 

area

42 96 42 96

OK Statewide No limits No limits No limits No limits

PA Statewide 42 75 42 75

SC Statewide No limits No limits No limits No limits

TN 5 Counties source specific 

RACT

source specific 

RACT

source specific 

RACT

source specific 

RACT

TX Dallas and Houston 

areas

9

(0.032 lb/mmBtu)

9

(0.032 lb/mmBtu)

9

(0.032 lb/mmBtu)

9

(0.032 lb/mmBtu)

VA Northern VA 42 65/77 42 65/77

WI Milwaukee 7 

county area

25 to 42 65 to 96 9 9

WV Statewide No limits No limits No limits No limits
12
13

Observations Regarding State NOx Rules for Gas Turbines:

 Geographic Applicability

 States in the OTR (CT, DE, MA, MD, NJ, NY, and PA) have NOx emission requirements that 

apply statewide, not just in ozone nonattainment areas. 

 Nine states (AL, AR, IN, KY, MI, MS, OK, SC, and WV) do not have regulations limiting NOx 

emissions.

 For the remaining states (GA, IL, LA, MO, NC, OH, TN, TX, VA, WI), the NOx emission 

control requirements only apply in ozone nonattainment areas. 

 Other Applicability Criteria

 States use a variety size thresholds. For example, Ohio’s rules differentiate between units < 3.5 

MW and > 3.5 MW. Wisconsin has requirements for three size ranges: 10-25 MW, 25-50 MW, 

and >50 MW. 

 State limits generally differ by type of fuel – gas or oil. Wisconsin also includes limits for 

biologically derived fuel. 

 Some states have different limits for simple-cycle and combined-cycle units. Other states have a

single limit that applies to both types of units.

 Form of NOx Limitation or Control Requirement

 States do not specify specific types of control techniques, but rather set a numerical emission 

limit. 

 Most states express limits in terms of “ppmv at 15% oxygen”. Some states use lbs/mmBtu, and 

the equivalent limits shown in the table above were calculated using based on Part 75 Eq-F5 and 

F-factors. New Jersey’s limits are in terms of lbs/MHr. 

 Stringency of NOx Limitation or Control Requirement

 Three areas have very low limits compared to other states/areas: the 45 county area in Georgia, 

Dallas and Houston-Galveston
14

Attachment 7 – IC Engines Greater than ~500 hp

NOx Limit (g/hp-hr)

State Geographic Area Gas-fired, 

Lean Burn

Gas-fired, 

Rich Burn Diesel Dual Fuel

AL Fine grid zone No limits No limits No limits No limits

AR Statewide No limits No limits No limits No limits

CT Statewide 2.5 2.5 8.0 8.0

DE Statewide Technology Stds. Technology Stds. Technology Stds. Technology Stds.

GA 45 county area ? ? ? ?

IL Chicago & St Louis 

areas

210 ppmvd @ 

15% O2 

(2.9 g/hp-hr)

150 ppmvd @ 

15% O2 

(2.2 g/hp-hr)

660 ppmvd @ 

15% O2

(9.1 g/hp-hr)

660 ppmvd @ 

15% O2

(9.1 g/hp-hr)

IN Statewide No limits No limits No limits No limits

KY Statewide No limits No limits No limits No limits

LA Baton Rouge 5 

counties & ROI

4.0 2.0 ? ?

MA Statewide 3.0 1.5 9.0 9.0

MD Select counties 150 ppmvd @ 

15% O2 

(1.7 g/hp-hr)

110 ppmvd @ 

15% O2 

(1.6 g/hp-hr)

175 ppmvd @ 

15% O2

(2.0 g/hp-hr)

125 ppmvd @ 

15% O2

(1.4 g/hp-hr)

MI Fine grid zone 3.0 1.5 2.3 1.5

MO St Louis area 3.0 10.0 2.5 to 9.5 2.5 - 8.5 2.5 - 6.0

MS Statewide No limits No limits No limits No limits

NC Charlotte Area 2.5 2.5 8.0 8.0

NJ Statewide 2.5 1.5 8.0 8.0

NY Statewide 1.5 1.5 2.3 2.3

OH Cleveland 3.0 3.0 3.0 3.0

OK Statewide No limits No limits No limits No limits

PA Statewide 3.0 2.0 8.0 8.0

SC Statewide No limits No limits No limits No limits

TN 5 Counties Source specific 

RACT

Source specific 

RACT

Source specific 

RACT

Source specific 

RACT

TX Dallas and Houston 

area

0.5 0.5 2.8 to 6.9 0.5

VA Northern VA Source specific 

RACT

Source specific 

RACT

Source specific 

RACT

Source specific 

RACT

WI Milwaukee 7 

county area

3.0 3.0 3.0 3.0

WV Statewide No limits No limits No limits No limits
15

Observations Regarding State NOx Rules for IC Engines:

 Geographic Applicability

 States in the OTR (CT, DE, MA, MD, NJ, NY, and PA) have NOx emission requirements that 

apply statewide, not just in ozone nonattainment areas. 

 Eight states (AL, AR, IN, KY, MS, OK, SC, and WV) do not have regulations limiting NOx 

emissions.

 For the remaining states (GA, IL, LA, MI, MO, NC, OH, TN, TX, VA, WI), the NOx emission 

control requirements only apply in ozone nonattainment areas. 

 Other Applicability Criteria

 States use a variety size thresholds. For example, Louisiana’s rules have separate limits for IC 

engines that are 150-300 hp, >300 hp, and >1500 hp. New York uses > 200 hp and > 400 hp. 

Delaware uses > 450 hp, while North Carolina uses > 650 hp.

 State limits generally differ by type of fuel – gas, oil, dual-fuel or landfill/digester gas. 

 A few states have different limits lean-burn and rich-burn engines. Other states have a single limit 

that applies to both types of units.

 Form of NOx Limitation or Control Requirement

 Most states express limits in terms of “gram per brake horsepower hour”. 

 Some states use “ppmvd @ 15% O2”, and the equivalent limits shown in the table above were 

calculated using conversion factors from ppmv @ 15% O2 to g/hp-hr from EPA ACT, July 1993 

EPA453-R-93-032.

 Delaware specifies control technology standards rather than numerical emission limits. 

 Stringency of NOx Limitation or Control Requirement

 Maryland, New Jersey, New York and the Dallas/Houston areas of Texas have limits that are 

more stringent than other states/areas.