EPA changed where near-road nitrogen dioxide monitors were required, not the concentration standards described in its rulemaking record. The final rule published and effective December 30, 2016 removed the January 1, 2017 installation requirement for Core Based Statistical Areas with populations of at least 500,000 but less than 1,000,000. This New Year coverage looks back at that action. [2016-31645]
The May 16 proposal explains the standards framework. The one-hour standard has a level of 100 parts per billion, using a 98th-percentile form averaged over three years; the retained annual standard is 53 parts per billion. The one-hour figure is therefore not a simple ceiling tested against every isolated hourly observation. The averaging form belongs with the number. [2016-11507]
Monitoring duties have their own categories. The final rule retains near-road requirements for areas of at least one million people and leaves area-wide and susceptible or vulnerable-population monitoring unchanged. Area-wide monitoring represents a neighborhood or larger spatial scale; it is not interchangeable with a measurement beside a major road. Removing a required future installation also does not establish that an existing station physically closed. [2016-31645]
EPA's proposal expected smaller areas to have similar or more likely lower near-road concentrations based on then-available data and population-traffic relationships. It acknowledged site-specific influences and uneven data completeness. That is the rationale behind the final decision, not proof about every smaller community. Together, the documents establish one EPA policy sequence rather than two independent confirmations of safe air. [2016-31645][2016-11507]
Source documents
- Revision to the Near-road NO2 Minimum Monitoring Requirementshttps://www.govinfo.gov/content/pkg/FR-2016-12-30/html/2016-31645.htm
- Revision to the Near-Road NO2 Minimum Monitoring Requirementshttps://www.govinfo.gov/content/pkg/FR-2016-05-16/html/2016-11507.htm