4. Regional Administrator Authority 

The following paragraphs provide background, rationale, and details for the final changes 

to Regional Administrator’s authority to use their discretion in requiring NO2 monitors in 

addition to those required in the minimum monitoring requirements of the two-tier network 

design. As discussed above in section III.B.2, the proposed rule required approximately 167 

near-road monitors distributed within CBSAs having populations of 350,000 or more persons. 

In response to various public comments, particularly from states, EPA is changing the population 

threshold by which one near-road NO2 monitor is minimally required in a CBSA to 500,000. 

EPA estimates that this change in the population threshold will result in a reduction in the 

number of minimally required near-road NO2 monitors by approximately forty monitors. EPA 

has also recognized (section II.F.4.d) that ethnic or racial minorities and individuals of low 

socioeconomic status are at particular risk of NO2-related health effects. The Administrator has 

therefore determined that it is appropriate and necessary to require the Regional Administrators 

to use their discretion, working in collaboration with states, and site these forty monitors in 

locations of low income or minority populations. In addition, the Regional Administrators, 

working with states, may take into account other considerations described below to site 

additional monitors. 

a. Proposed Regional Administrator Authority 

 EPA proposed that Regional Administrators have the authority to require monitoring at 

their discretion in particular instances. First, EPA proposed that the Regional Administrator will 

have discretion to require monitoring above the minimum requirements as necessary to address 

situations where the required near-road monitors do not represent a location or locations where 

the expected maximum hourly NO2 concentrations exist in a CBSA. Second, EPA proposed to 
allow Regional Administrators the discretion to require additional near-road monitoring sites to 

address circumstances where minimum monitoring requirements are not sufficient to meet 

monitoring objectives, such as a situation where there is a variety of exposure scenarios to NO2

concentrations in an area because of the variety in the amount or types of fleet mix, congestion 

patterns, terrain, or geographic areas within a CBSA. And third, EPA proposed that Regional 

Administrators shall have the discretion to require additional area-wide NO2 monitoring sites 

above the minimum requirements for area-wide monitors where the minimum requirements are 

not sufficient to meet monitoring objectives.have the discretion to require additional area-wide 

NO2 monitoring sites above the minimum monitoring requirements where the minimum 

monitoring requirements for area-wide monitors are not sufficient to meet monitoring objectives. 

b. Comments 

EPA received comments from the Center on Race, Poverty and Environment expressing 

concern that the proposed monitoring provisions fail to consider "disproportionately impacted 

communities" which include people of color and of lower socioeconomic status that make up the 

"environmental justice communities." The commenter argues that this is "a gaping hole" in the 

proposed monitoring system and disproportionately impacts minority and low income 

populations in rural communities. In addition, the National Tribal Air Association stated that 

“Indian tribes and Alaska Natives are highly susceptible to health impacts as a result of NO2

exposure” and “the prevalence and severity of asthma is higher among certain ethnic or racial 

groups such as Indian tribes and Alaska Natives,” which is also discussed in section II.B.4 and 

the ISA (ISA, section 4.4). 

The proposed rule provided the Regional Administrators with the authority to use their 

discretion and consider certain factors to require monitors above the minimum number in a 
CBSA. The proposal described that one example where a Regional Administrator might require 

an additional near-road monitor could be where "a particular community or neighborhood is 

significantly or uniquely affected by road emissions." EPA recognizes, as noted in section 

II.F.4.d, that ethnic or racial minorities and individuals of low socioeconomic status are at 

particular risk of NO2-related health effects, both because of increased exposure and because 

these groups have a higher prevalence of asthma and higher hospitalization rates for asthma. As 

noted above, in conjunction with raising the threshold for requiring one near-road NO2 monitor 

in a CBSA to those with 500,000 persons or more, EPA is requiring the Regional Administrators, 

under their discretionary authority, to work with states in development of their monitoring plans 

to place an additional forty monitors, under their discretionary authority focusing primarily on 

areas where low income or minority populations (at-risk populations) are located. To address the 

risks of increased exposure to these at-risk groups, the Administrator has determined that it is 

appropriate and necessary to ensure that in siting these additional forty monitors under this 

provision the Regional Administrators site them primarily in locations where at-risk populations 

are exposed to NO2 concentrations that have the potential to exceed the NAAQS (due to 

emissions from motor vehicles, point sources, or area sources). As a result of this action, the 

total number of monitors required through this rulemaking is not substantially different than the 

total number of minimally required monitors presented in the proposal, however a subset of the 

total will target on at-risk popu.lations.

The EPA also received comments from some state groups (e.g. the New York 

Department of Environmental Conservation (NYSDEC), New York Department of 

Transportation (NYSDOT), and the New York City Law Department) and an industry group (the 

Council of Industrial Boiler Operators) who requested greater clarification on how Regional 

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Administrators may use their authority to require additional monitors above the minimum 

requirements. For example, the Council of Industrial Boiler Operators stated that “this [Regional 

Administrator authority] unreasonably vests an unbounded amount of discretion in EPA to 

determine when "minimum monitoring requirements are not sufficient" and which 

neighborhoods are "uniquely affected," and impose additional monitoring requirements where all 

applicable monitoring requirements are already met by the State and local agency.” 

 The Regional Administrator authority to require additional monitoring above the 

minimum required is not unique to NO2. For example, Regional Administrators have or are 

proposed to have the authority to use their discretion to require additional Pb monitors (40 CFR 

Part 58 Appendix D section 4.5), and have the discretion to work with state or locals in 

designing and/or maintaining an appropriate ozone network, per 40 CFR Part 58 Appendix D 

section 4.1 EPA believes that while the monitoring network is sufficiently sized and focused, we 

recognized that a nationally applicable network design may not always account for all locations 

where potentially high concentrations approaching or exceeding the NAAQS may exist in every 

area of the country . Therefore, EPA believes it is important to have the ability to address issues 

where gaps may exist in the minimally required monitoring network, which is best accomplished 

through the Regional Administrator authority to require monitoring above the minimum 

requirements. 

One example where the Regional Administrator may exercise their discretion in requiring 

a monitor might be a location or community impacted by a stationary source where the required 

near-road NO2 monitor site is not the location of maximum hourly concentration in an area, or in 

a situation where that same stationary source exists in an area that has no minimum monitoring 

requirements.. In this example, that un-monitored location could be the location of expected 
maximum concentration in that area. For any given area, there is the possibility that the 

maximum NO2 concentrations could be attributed to impacts from one, or a combination of, 

multiple sources that could include point, area, and non-road source emissions in addition to onroad mobile source emissions. As a result, the Regional Administrator may choose to require 

monitoring in such a location. Alternatively, in this same example, if the sources responsible for 

this situation are producing more widespread impacts on a community or relatively larger area, 

the Regional Administrator may require an area-wide monitor to assess wider population 

exposures, or to support other monitor objectives served by area-wide monitors such as 

photochemical pollutant assessment or pollutant forecasting. 

Another example where the Regional Administrator may require additional monitoring 

could be in situations where a state or local agency is fulfilling its minimum monitoring 

requirements with an appropriate number of near-road monitors, but an additional and somewhat 

unique location is identified where near-road population exposure exists at concentrations near or 

above the NAAQS. For this example, the location might be unique due differences in fleet mix, 

congestion patterns, terrain, or geographic area, relative to any minimally required monitoring 

site(s) in that area. We note that such areas might exist in CBSAs with populations less than 

500,000 persons, and as a result, the Regional Administrator would be in a position to exercise 

this discretion for any area of the country where these situations may exist. 

EPA recognizes that high concentrations of NO2 that approach or exceed the NAAQS 

could potentially occur in a variety of scenarios in an area, and we believe that Regional 

Administrators should have the discretion to require additional monitoring when a location is 

identified based on the factors discussed in the paragraph above. In such situations, state or EPA 

Regional staff are likely to have identified these locations through data analysis, such as the 
evaluation of existing ambient data and/or emissions data, or through air quality modeling. Such 

information may indicate that an area might have ground-level NO2 concentrations that may 

approach or exceed the NAAQS, and that there is potential for population exposure to those high 

concentrations. 

The process by which a Regional Administrator would use this authority is part of a 

collaborative process with state agencies. Typically, Regional Administrators work with state 

and local agencies to design and/or maintain the most appropriate NO2 network to meetservice

the needs forof a given area. For all the situations where a Regional Administrator may require 

additional monitoring, including the forty40 additional monitors the Regional AdministratorsAs

are required to locate, EPA expects that Regional Administrators would work on a case-by-case 

basis with states in that decision making process. Further, for the forty additional monitors that 

will primarily on at-risk communities, EPA intends to work with states to develop criteria to aid 

in the site selection process.

c. Conclusions on Regional Administrator Authority 

Recognizing that a nationally applicable monitoring network design may not always 

include sites with potentially high concentrations due to case-by-case differences in various 

locations, and in response to public comments that highlight some of these differences and 

further consideration of the monitoring network, the Administrator deems it necessary to provide 

the Regional Administrator the discretion to require additional monitoring above the minimum 

requirements.In response to public comments and further consideration of the monitoring 

network, the Administrator deems it necessary to provide the RAs the discretion to require 

additional monitoring above the minimum requirements. EPA is requiring that Regional 
Administrators shall use their discretion to work with states to site forty additional NO2

monitors in locations where low income or minority populations are exposed to NO2

concentrations that have the potential to approach or exceed the NAAQS (e.g., due to emissions 

from mobile sources, point sources, or area sources). In addition, Regional Administrators shall 

have the discretion to require monitoring above the minimum requirements as necessary to 

address situations (1) where the required near-road monitors do not represent a location or 

locations where the expected maximum hourly NO2 concentrations exist in an area, or in 

situations where such a location exists in an area that has no minimum monitoring requirements; 

(2) where minimum monitoring requirements are not sufficient to meet monitoring objectives, 

such as a location that is unique, relative to the minimally required near-road monitors in the 

area, due to factors that might include fleet mix, congestion patterns, terrain, or geographic 

location in an area, or in an areas that do not have minimally required near-road monitors where 

there are indications that NO2 concentrations may be approaching or exceeding the NAAQS; and 

(3) where the minimum monitoring requirements for area-wide monitors are not sufficient to 

meet monitoring objectives. 

In these situations where a Regional Administrator may consider the need for additional 

monitoring, EPA expects that the state and the Regional Administrator wouldill work together to 

evaluate quantitative evidence that suggests an area may warrant additional monitoring. EPA 

also notes that if additional monitoring should be required, as negotiated between the Regional 

Administrator and the state, the state will modify information in its Annual Monitoring Network 

Plan to include any potential new sites prior to any approval by the EPA Regional Administrator.