Summary	of	Interagency	Working	Comments	on	Draft	Language	under	

EO12866/13563	Interagency	Review.		Subject	to	Further	Policy	Review.

1

Environmental Protection Agency (EPA): Proposed Rule

Cross-State Air Pollution Rule for the 2008 Ozone 

National Ambient Air Quality Standards

RIN 2060-AS05

General Comments

1. The proposed rule clearly intends to manage ozone transport through CSAPR, focusing on 

EGUs. However, anthropogenic emissions from Canada and Mexico and Fires are 

specifically identified as contribution categories in the “source apportionment run” (page 103 

of the preamble). The reviewer believes that states could propose controls on wildland fire 

emissions, since these emissions are specifically included as a contribution category, even if 

the primary control mechanism focuses on EGUs. The reviewer also believes that wildland 

fire emissions may contribute to ozone NAAQS exceedances in nonattainment and 

maintenance areas in a number of the 23 states. 

EPA Response: While wildfires do contribute to ozone formation, the EPA did not consider 

fires to be part of the anthropogenic emissions that were tracked in the source apportionment 

modeling for each state. The fire emissions were “tagged” as a separate source category (for 

the entire domain, not for each individual state), and therefore the interstate ozone 

contributions did not include contributions from either wildfires or prescribed fires. The 

domain wide wildfire and prescribed fire ozone contributions to each downwind ozone 

receptor are quantified in the summary model contributions. 

2. Wildland fire emissions are highly variable annually in source, impact, geographic area, and 

extent. In 2015, emissions impacts the CSAPR area from Alaska, California, the Pacific 

Northwest, and especially, from Canada. In other years, wildland fire emissions from 

Mexico, Texas or the Southeastern states have impacted the CSAPR. Therefore, the reviewer 

recommends clarifying that the modeled baseline year of 2017 in the RIA includes the range 

of possible wildland fire emissions.

EPA Response: The modeling emissions and meteorological base year is 2011. Therefore, 

“actual” wildfire and prescribed fire emissions for 2011 were used in the modeling. These are 

based on emissions modeling techniques which estimate the emissions that occurred in 2011 

from fires and place those emissions in the location that they occurred (the grid cell) at the 

time that they occurred. For the future year 2017 modeling, the anthropogenic emissions are 

projected to 2017 based on our best estimate of growth and controls between 2011 and 2017. 

However the fire emissions are held constant between the base and future years (2011 and 

2017) due to the fact that we are most interested in the impact of expected anthropogenic 

emissions changes and we don’t know how or where fires would occur in the future 

compared to what occurred in 2011. 

3. Despite the impacts of wildland fire emissions, there are very positive effects from prescribed 

fire and other wildland fire management actions that reduce wildfire risks. Therefore, the 
Summary	of	Interagency	Working	Comments	on	Draft	Language	under	

EO12866/13563	Interagency	Review.		Subject	to	Further	Policy	Review.

2

reviewer recommends that language included in the attachment to the EPA October 1, 2015 

Memorandum on Implementing the 2015 Ozone National Ambient Air Quality Standards to 

Regional Administrators be incorporated within the preamble of this proposed rule. This 

language provides a succinct summary of many concepts regarding the ecological role of fire, 

and the relationship between wildland fire (wildfire and prescribed fire) and the management 

of ozone and ozone precursor emissions, that have been published over the past year and 

have been included in other air quality rulemaking packages.

a. “Emissions from Wildland Fires. We understand that fire is an unavoidable 

occurrence on many types of wildland, and that changing climate conditions will 

increase the occurrence of damaging wildfires unless fuel loads are managed by other 

means including science-based use of prescribed fire.12,13,14 Emissions from fires on 

wildland, particularly large wildfires, can impact concentrations of ozone and other 

harmful pollutants, such as PM2.5, both in the locations with fire and down wind. In 

areas where wildfire have been prevalent or are likely we encourage air agencies to 

work with state, federal and private land managers on promoting prescribed fire and 

other strategies that may reduce wildfire emissions and their effects on ozone 

exceedances; we appreciate that such strategies may have other public safety, 

ecological, and property protection benefits as well. Recognizing the importance of 

various fire management strategies, in the proposed revisions to the Exceptional 

Events Rule we intend to encourage air agencies to rely on burn managers’ use of 

basic smoke management practices15 by identifying a set of generally applicable 

practices that would be employed during prescribed fires. The EPA and the federal 

land management agencies will support state efforts to educate the public on the 

ecological role of fire, and wildfire and prescribed fire concepts. Where a prescribed 

fire program has been developed and is being implemented in and/or upwind of a 

nonattainment area, the EPA recommends that air agencies account for the expected 

prescribed fire emissions in the attainment and maintenance planning process. In 

those areas where prescribed fires are known to be capable of causing occasional 

ozone exceedances, the EPA will continue to work with air agencies and stakeholders 

to improve the long-term effectiveness of the existing basic smoke management 

practices and smoke management programs.”

EPA Response:

Fires were specifically excluded from the upwind state to downwind receptor ozone 

contributions. So the upwind emissions that are available to be reduced to eliminate significant 

contribution do not include fire emissions. This rule specifically addresses interstate transport of 

anthropogenic ozone and ozone precursors. EPA will add language noting that EPA recognizes 

that both in-state and upwind wildfires may contribute to ozone and EPA encourages all states to 

consider how appropriate use of prescribed fire may result in fewer ozone exceedances for both 

them and their neighbors, to the benefit of public health.

4. Reviewer recommends referencing the pending Exceptional Events Rule proposal that was 

referred to in the 2015 Ozone NAAQS.
Summary	of	Interagency	Working	Comments	on	Draft	Language	under	

EO12866/13563	Interagency	Review.		Subject	to	Further	Policy	Review.

3

EPA Response:

EPA will add the following language: “Wildland fire emissions may contribute to ozone 

exceedances, under the exceptional events rules in 40 CFR 50.14, certain emissions from 

wildland fires can be excluded from any determination of a NAAQS exceedance if they meet 

certain requirements. Among those exceptional event requirements for wildland fires is the 

requirement to implement a certified Smoke Management Program or employee basic smoke 

management practices, both of which are used to control wildland fire emissions. EPA is in 

the process of undertaking a revision of the exceptional events rules to further define and 

clarify the treatment of wildland fires, but there is and will continue to be a regulatory

mechanism for excluding such emissions from any ozone exceedance determinations, so long

as those emissions meet the relevant criteria.”

Regulatory Impact Analysis

1. Page 3-8, Table 3-1. Reviewer recommends using standard language for wildland fires and 

therefore changing “Wild and Prescribed Fires” to “Wildfires and Prescribed Fires.

EPA Response: EPA will update the table header consistent with the comment.