US expert panel calls for ammonia-based NAAQS

Members of the US Environment Protection Agency’s Clean Air Scientific Advisory Committee (CASAC) examining the ecological effects of nitrogen oxides, sulphur oxides and particulate matter are urging the EPA to set a national ambient air quality standard (NAAQS) for nitrogen to mitigate rising ammonia emissions, a long-standing but so far unsuccessful goal of environmentalists.

There are currently NAAQS established for NOx, SOx, PM, carbon monoxide, lead and ozone under the Clean Air Act, requiring states to craft plans outlining control measures to cut these criteria air pollutants. But the EPA has so far not shown interest in doing so for ammonia, which contributes to adverse human health effects as well as increased nitrogen loading for water bodies and the environment.

Listing ammonia as a criteria pollutant would trigger air permitting requirements under the prevention of significant deterioration and new source review programmes, as well as the Title V operating permit programme. Such efforts have been strongly opposed by industry groups, especially the agriculture sector whose animal feeding operations are one of the largest sources of ammonia emissions.

The CASAC’s integrated science assessment will serve to support a review of the “secondary” NAAQS for NOx and SOx, which could result in a novel combined standard. Secondary standards are intended to protect the environment, while primary standards are aimed at protecting human health. The current review of the secondary standards will not conclude until 2020 or later.

Source: Car Lines No. 5, September 2017.