The skies, the limits: Assessing the benefits and drawbacks of tighter US soot emission standards

Abstract

The US Environmental Protection Agency (EPA) sets National Ambient Air Quality Standards (NAAQS) for six "criteria" pollutants that are particularly damaging to human health. In December 2012, the EPA announced that it would tighten the limit on one criteria pollutant, fine particulate matter (PM 2.5) or soot, which is emitted by diesel engines and industrial activities (among other sources) and is associated with detrimental cardiovascular and respiratory conditions. The tighter limits were praised by public health advocates but denounced by stakeholders in manufacturing industries. The goal of this discussion-based activity is for students to think critically about this environmental health issue and assess the benefits and drawbacks of the new EPA limit. After completing the activity, students should be able to (1) identify why PM 2.5 is an EPA criteria pollutant that can be harmful to human health, (2) discuss two competing perspectives on the 2012 EPA soot regulation and argue in favor or opposition of the new policy, and (3) explain how new scientific knowledge on the composition of soot could help develop better solutions for its regulation.