What: On July 17, 2026, the U.S. Environmental Protection Agency (EPA) released a document titled “Integrated Science Assessment for Oxides of Nitrogen—Health Criteria, External Review Draft” (“draft ISA”) for public comment.
Why: Under the Clean Air Act (CAA), ISAs serve as the scientific foundation for establishing and reviewing the primary (health-based) and secondary (welfare-based) national ambient air quality standards (NAAQS).
The NAAQS set CAA standards for six different monitored pollutants (particulate matter, ozone, carbon monoxide, lead, nitrogen dioxide, and sulfur dioxide). These standards must be reevaluated every five years. Counties not in compliance with the NAAQS standards are in violation of the CAA and can face withholding of federal funds.
Oxides of nitrogen (NOx) comprise a group of highly reactive gases including nitrogen dioxide (NO2), which is the indicator for the primary NOx NAAQS. NO2 forms quickly from emissions from cars, trucks and buses, power plants, and off-road equipment.
Counties out of compliance with the NAAQS face penalties until they can come back into compliance. To comply with the NAAQS, counties often place additional restrictions on small entities within their borders. These regulations can require small businesses to purchase expensive new equipment and not use the existing equipment they have, so the county can attain stricter emissions standards.
Action: Read the draft ISA and submit comments before the September 15, 2026, deadline.
FEDERAL REGISTER NOTICE:
DRAFT ISA:
Integrated Science Assessment for Oxides of Nitrogen – Health Criteria
(PDF, 1,628 KB)
CONTACT: Nick Goldstein
EMAIL: nick.goldstein@sba.gov
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