Responses to Significant Comments on the

2012 Proposed Rule on the

Revision to Ambient Nitrogen 

Dioxide Monitoring Requirements

(October 19, 2012; 77 FR 64244)

Docket Number EPA-HQ-OAR-2012-0486

U.S. Environmental Protection Agency
Table of Contents

I. Introduction

II. Responses to comments on the revision of the near-road NO2 monitor implementation 

schedule.

III. Responses to comments on the change in the NO2 Annual Monitoring Network Plan 

approval authority.

IV. Responses to comments on general monitoring and implementation.
Frequently Cited Documents

The following documents are frequently cited throughout the EPA’s response to comments, often 

by means of the short names listed below:

Preamble to the final rule:

Preamble to the Final Rule on Revision to Ambient Nitrogen Dioxide Monitoring Requirements; 

to be published in the Federal Register in January or February of 2012.

Proposal notice:

Revision to Ambient Nitrogen Dioxide Monitoring Requirements: Proposed Rule.

77 FR 34244, October 19, 2012.
Acronyms and Abbreviations

EPA U.S. Environmental Protection Agency

NAAQS National Ambient Air Quality Standard

NO2 Nitrogen Dioxide

CAA Clean Air Act
I. Introduction

This document, together with the preamble to the final rule on the Revision to Ambient 

Nitrogen Dioxide Monitoring Requirements, presents the responses of the Environmental 

Protection Agency (EPA) to the public comments received on the 2012 Revisions to Ambient 

Nitrogen Dioxide Monitoring Requirements proposal notice (77 FR 64244). All significant 

issues raised in timely public comments have been addressed.

In cases where there were a number of comments that addressed similar issues, this 

response-to-comments document does not generally cross-reference each response to the 

commenter(s) who raised the particular issue involved, although commenters are identified in 

some cases where they provided particularly detailed comments that were used to frame the 

overall response on an issue.

The responses presented in this document are intended to augment the responses to

comments that appear in the preamble to the final rule or to address comments not discussed in

the preamble to the final rule. Although portions of the preamble to the final rule are paraphrased 

in this document where useful to add clarity to responses, to the extent any ambiguity is 

introduced by this paraphrasing, the preamble itself remains the definitive statement of the

rationale for the revisions to the standards adopted in the final rule.

In many instances, particular responses presented in this document include cross

references to responses on related issues that are located either in the preamble to the final rule, 

or in this Response to Comments document. In other instances, the comment is appropriately 

addressed by the agency’s discussion in other parts of the record. All issues on which the 

Administrator is taking final action in the final rule are addressed in the rulemaking record.

Accordingly, this Response to Comments document, together with the preamble to the 

final rule and the Notice of Proposed Rulemaking should be considered collectively as the EPA’s 

response to all of the significant comments submitted on the EPA’s 2012 Revisions to Ambient 

Nitrogen Dioxide Monitoring Requirements proposed rule. This document incorporates directly 

or by reference the significant public comments addressed in the preamble to the final rule, as 

well as other significant public comments that were submitted on the proposed rule.

Consistent with the final decisions presented in the notice of final rulemaking, comments

on the following topics are addressed in this document: changes to the ambient Nitrogen 

Dioxide (NO2) monitoring requirements (section II.A); changes in Annual Monitoring Network 

Plan approval authority (section II.B); and responses to general monitoring and implementation 

issues.
II. Responses to Comments on the Revision of the Near-road NO2 

Monitor Implementation Schedule 

While a majority of commenters who made statements regarding the proposed revision to 

adjust the dates by which near-road NO2 monitors are required were supportive, the EPA 

received one comment against the proposed revisions. 

Comment: One commenter stated that the proposed revision would lead to a trend in which 

the EPA will “...continuously revise the deadline, as there will always be funding 

issues in our current economy.” The commenter goes on to suggest that 

postponing may also be interpreted to mean that the EPA is minimizing the 

priority for near-road NO2 monitoring. 

Response: As noted in the preamble to the final rule (Section II.A.2), the EPA is not 

minimizing ambient air monitoring in the near-road environment through this 

action. The EPA is taking action to adjust the timeline by which required nearroad monitors must be in place to reflect the reality of limited resources between 

the federal, state, and local air agencies. The EPA is not reducing the amount of 

required monitoring, but is adjusting the schedule to match the forecasted 

available funding, which will have to occur over multiple years.

III. Responses to Comments on the Change in the NO2 Annual 

Monitoring Network Plan Approval Authority

All public comments received on the proposal to shift the approval authority of state 

Annual Monitoring Network Plans from the EPA Administrator to the EPA Regional 

Administrators were fully supportive. As discussed in the preamble to the final rule (Section 

II.B), the proposal is being finalized as proposed.

IV. Response to Comments on General Monitoring and 

Implementation Issues

Comment: Multiple state and multi-state representative groups commented that full funding 

for capital and long-term operations and maintenance need to be provided in order

for states to implement the near-road NO2 network. For example, the South 

Carolina Department of Health and Environmental Control stated that “...[Clean 

Air Act section 103 funds are] necessary to support implementation and equitable 

allocation of [Clean Air Act section] 105 funding be provided for the continued 

cost of operations and maintenance of any federally mandated ambient monitoring 

networks.”
Response: As discussed in the preamble to the final rule, the EPA recognizes that there are 

funding and resource shortfalls at the federal, state, and local levels. Although the 

requirement to install these required near-road NO2 monitors is not dependent on 

federal funds being available, the EPA will continue to attempt to secure 

sufficient funding for the implementation of the near-road NO2 network. The 

EPA believes it will be able to identify those grant funds over time, allowing the 

network to phase-in as was proposed and finalized. The EPA will continue to 

work with States to identify strategies for optimizing networks as a mechanism 

for controlling ongoing maintenance and operational costs. Both the annual

monitoring network planning process and 5-year network assessments provide 

pathways for states to engage in such conversations with their respective Regional 

Offices.

Comment: One commenter stated that this rule suggests “...to increase placement of air 

quality monitors near ‘major roads in larger urban areas’.”

Response: The EPA notes that this rulemaking is not increasing the placement (or number) 

of NO2 monitors near-roads in larger urban areas. The action of requiring nearroad NO2 monitors was promulgated in the 2010 NO2 NAAQS rulemaking (75 

FR 6474). This rulemaking is only changing the dates when required near-road 

NO2 monitors are to be implemented. 

Comment: One commenter stated that the EPA should avoid near-road NO2 monitoring, 

which highlights “...only the worst areas for emissions instead of focusing on the 

more complete, and accurate picture of our nation’s success in improving air 

quality.” The commenter also states that required monitoring should instead 

balance air quality monitor placement between “high and low travelled areas” as a 

means to obtain an assessment of an entire county’s air quality.

Response: We note that the rationale behind the requirements to monitoring NO2 nearroads, as articulated in the 2010 NO2 NAAQS rulemaking (75 FR 6474), is to 

support the NAAQS which was revised to protect against exposures to peak NO2

concentrations that can occur anywhere in an area, which includes the near-road 

environment. 

Comment: One commenter stated “the phased approach allows for time to analyze the results 

from the first phase implemented in January of [2014] in order to determine 

whether future proposed phases are required. The EPA should analyze data and 

experience gained from the first phase and work with state and local agencies to 

determine whether the future phase, especially the third phase due in January 

2017, is necessary.”
Response: The requirements for near-road NO2 monitoring, promulgated in the 2010 NO2

NAAQS revision, were based on available data, or lack thereof, in supporting the 

NAAQS. The EPA anticipates that any revision to the number or focus of NO2

monitors would be part of the next NO2 NAAQS review, where new monitoring 

data would be considered along with available health data and analysis used to 

evaluate the suitability of the NAAQS itself. 

Comment: Multiple commenters requested that the EPA address nonattainment issues that 

may arise from forthcoming near-road data. Several of those same commenters 

went on to request that the EPA work with states to determine how the near-road 

data will be used in determining potential nonattainment areas as well as

implications to air permitting programs. Another commenter questioned how the 

staggered implementation of required near-road NO2 monitors will affect the 

designation process, particularly if phasing-in the monitors would result in 

multiple rounds of designations. This commenter noted that each round of 

designations requires intensive staff time and resources, and suggested that the 

EPA consider a single round of designations resulting from near-road NO2 data, 

when all the monitors have reported a sufficient amount of data.

Response: Once three years of air quality data have been collected from a given newly sited 

monitor, the EPA will be able to assess this data and work with the states to 

determine appropriate steps to address designations and permitting-related issues. 

On January 20, 2012, the EPA completed initial designations for the 2010 NO2 

NAAQS for all areas of the country. Once 3 years of air quality data are available

from a monitor, the EPA has discretion under the CAA to redesignate areas as 

appropriate from ‘‘unclassifiable’’ to ‘‘attainment’’ or ‘‘nonattainment.’’ For 

monitors deployed beginning in 2014, sufficient data to evaluate potential 

redesignations would be available after 2016 (77 FR 9534-9535). The EPA is 

aware that phasing-in the new monitors will mean that 3 years of data will not be 

available for all monitors at the same time. The EPA is also aware of the federal 

and state resources required to conduct designations, and we anticipate taking this 

type of information into account in working with states to determine appropriate 

next steps.