Summary of Interagency Working Comments on Draft Language under EO12866 Interagency Review. 

Subject to Further Policy Review.

1. It is unclear how one translates the weak relationships observed in epidemiological 

studies that use ambient monitoring to determining a maximum level of NO2 one 

should allow near roadways. CASAC indicated a similar concern during their meeting 

on the proposed NAAQS. 

2. Please crosswalk the methods used in the EPA meta-analysis with those used by 

Goodman. There is a newly published article “Meta-analysis of nitrogen dioxide exposure 

and airway hyper-responsiveness in asthmatics” by Goodman et al Critical Reviews in 

Toxicology 2009; 39(9): 719-742. 

3. Are the levels being referred to here the increased airway responsiveness shown in the 

meta-analysis at 100ppb? EPA states that the new standard is designed to limit peak 

exposures at concentrations that have been reported to increase airway responsiveness in 

asthmatics. If so, does a peak standard set at 100 ppb contain a margin of safety? As EPA 

points out, it is possible that similar effects occur below 100 ppb. 

4. The preamble seems to imply that the margin of safety is essentially inherent in the fact 

that we are unsure whether these responses seen at 100 ppb are adverse. If this is the 

case, and symptoms also were not reported at 200 ppb does at what point does the 

margin of safety begin? At 300 ppb or 400 ppb? Why is the lowest level at which clinical 

studies were conducted the correct place for the standard if similarly equivocal results were 

found at higher levels? 

5. The studies referred to in the ISA dealt with traffic density, but the statements on page 

93 about the population at risk do not. The statement on page 93 (and associated footnote 

18) add confusion. It seems unlikely that NO2 concentrations next to railways are equivalent 

to those next to four-lane highways, and four-lane roads aren’t necessarily heavy traffic.

6. The mandate for a new compliance network could be delayed until there is sufficient 

science to support the approach. The draft preamble and docket present inadequate science 

to inform a decision on the near-roadway network, and the agency should consider removing 

this requirement, eventually addressing the issue through a separate implementation 

rulemaking, an approach that is consistent with previous NAAQS reviews.

EPA’s Office of Research and Development is about half way through a series of nearroadway studies in Las Vegas, Raleigh and Detroit. It would be appropriate to analyze the 

results of these extensive research efforts in order to properly inform the monitoring network, 

and estimate the degree of noncompliance that would result from the monitoring mandate.

7. Comments received from State governments seem overwhelmingly to oppose to the new 

monitoring strategy, yet the preamble seems to focus on positive comments. In 

particular, the preamble text does not seem responsive to the concerns expressed in 

comments of North Carolina, New York DOT, Arkansas, Virginia, New Mexico, 

Mississippi, Tennessee, Kentucky, Indiana, Michigan, Missouri, Alaska, Illinois, California, 

Alabama, Texas, Iowa, and Wisconsin.
Summary of Interagency Working Comments on Draft Language under EO12866 Interagency Review. 

Subject to Further Policy Review.

NACAA and the states object to this new mandate, citing concerns about the science, safety, 

lack of flexibility, cost, discordance with population exposure, and the states’ inability to 

control the relevant emissions. State commenters also mention that there was insufficient 

notice and comment and limited CASAC review of the strategy, since EPA had previously 

committed to an ANPR which was never eventually published.

8. The RIA is unable to robustly estimate the degree to which exceedence of the new

standard may occur near roads, and has made no attempt to model the near-roadway 

concentrations as a function of traffic density.

5. The Agency should clarify the types of PM reduced as the result of the proposed 

NAAQS. In earlier conversation, staff thought that while the great majority of the PM2.5

benefits came from reduced NO2, that there might also have been some reduction of other 

types of PM2.5

EPA's view continues to be that all types of PM

, perhaps through an on- or off-road diesel program of some sort. 

2.5 are thought to be equally harmful per unit 

of mass, and we also recognize that this RIA is not the place for discussion of this issue. But 

we do think that it would be important to note for the record other types of PM2.5, other than 

nitrates, which might be reduced as part of the NO2

In reading the NO2 preamble and RIA documents, and in using a "find" function, we couldn't 

find any mention of any other type of PM that was reduced. If this is correct, the suggestion 

would be to add a sentence on pg. 4 of Ch. 4 of the RIA, after this sentence:

NAAQS proposal, if this is the case. An 

efficient way of providing this discussion is perhaps through the use of a pie-chart, similar to 

that used in several recent rules, which breaks down the types of PM reduced and states that 

there is uncertainty in the size of the PM benefits introduced by questions of differential 

toxicity.

"Our estimate of PM2.5 co-control benefits is therefore based on the total PM2.5

The added sentence would say: 

emissions 

controlled by sector and multiplied by this per-ton value."

"The PM2.5 emissions reduced are exclusively PM2.5 which derive from NO2

If, on the other hand, there were some reductions in PM

emissions, for example 

nitrates."

2.5 species other than those formed 

from NO2

"The PM

emissions, then we would propose the following sentence instead of the one just 

offered:

2.5 emissions estimated to be reduced are almost all PM2.5 which derive from NO2

6. Reviewers suggest including a sentence to the preamble to clarify the potential for 

climate change impacts. Reviewers offered a comment earlier in the process pointing to a 

new research article by Drew Shindell et al. Shindell works closely with Jim Hansen in the 

GISS research lab. That article showed that reducing NO2 actually caused a net increase in 

emissions, 

for example nitrates, but a small proportion consist of _____."
Summary of Interagency Working Comments on Draft Language under EO12866 Interagency Review. 

Subject to Further Policy Review.

global warming, though complicated atmospheric processes. It is too early to draw hard 

conclusions on the size of the error bands around the findings of Shindell et al (2009). There 

is not enough time in this rulemaking to attempt to quantify the increase in global warming 

potential as a result of reductions in NO2 in the proposed rule -- the amount might be 

meaningful, or it might be vanishingly small. However, it seems important to recognize in 

this RIA that there is an issue. We couldn't find mention of "global warming" or "climate 

change" in any of the RIA documents, or in the actual proposed rule.

Reviewers suggest that a sentence such as this one be incorporated into the preamble at an 

appropriate location:

"Climate change impacts of emissions such as NO2, which have not been extensively studied with 

regard to their impacts on net warming, are only now beginning to be investigated. Investigation 

of complex atmospheric chemical reactions involving NO2 now suggests that decreases in NO2

might actually lead to an increase in global warming, inclusive of impacts on reducing 

tropospheric ozone, a greenhouse gas. Quantification of such an impact has not been done. Since 

work on this issue is only beginning, an analysis of the quantified impacts of reduction in NO2 on 

climate cannot yet be provided."