NESHAPs A Glimpse into their Ongoing Revolution

The National Emission Standards for Hazardous Air Pollutants, or NESHAPs, are federal regulations that focus on the emissions of air contaminants that the U.S. Environmental Protection Agency (EPA) considers to have toxic health effects. Unlike several other EPA air pollution control programs, NESHAPs can affect sources that are newly constructed or previously existing, regardless of the emission unit requiring an air permit, and regardless of the size of the facility. 
by Brian Noel 

Nationwide regulation of hazardous air pollutants (HAPs) began in 1970 with the issuance of the U.S. Clean Air Act (CAA) and the requirement, within Section 112 of the CAA, to identify and control air contaminants that “cause or contribute to an increase in mortality or an increase in serious irreversible, or incapacitating, reversible illness.”1 Initially, EPA conducted research and developed a list of eight HAPs, and over 20 years promulgated fewer than 25 regulations within 40 CFR Part 61 to control those pollutants to with the purpose to provide an “ample margin of safety to protect public health.” Each of these early NESHAPs focused on controlling emissions of individual HAPs from a specific industry group, or the emissions of the compounds regardless of industry.

This risk-based approach to regulating HAPs remained largely unchanged until the overhaul of the CAA in 1990. The change in HAPs regulation was made, in large part, due to the limited number of NESHAPs issued by EPA, and the challenges to the risk analysis required under the original CAA.2 Under the 1990 CAA, the focus of regulating HAP shifted to establishing required control technologies or work practices for the regulated source categories. Additionally, EPA focused on controlling groups of HAPs from specific industrial sectors rather than the earlier approach of focusing on individual HAPs. In the 26 years since the 1990 CAA Amendments, more than 130 Maximum Achievable Control Technology (MACT) and/or Generally Available Control Technology (GACT) standards have been promulgated within 40 CFR Part 63, addressing emissions of HAPs from dozens of source categories at large and small emitters, and the number of regulated HAPs has expanded to 187.

In addition to expanding the number of chemicals designated as HAPs and the shift to technology-based standards, the 1990 CAA Amendments introduced the requirement to regulate sources that affect urban air quality. In this issue, Jennifer Kelley discusses the impact of HAPs emissions on urban air quality and the NESHAPs that focus on area sources (i.e., those sources of HAPs that do not meet the major source threshold). As Kelley explains, what began as a mandate to protect the health and welfare of residents of urban areas from risks associated with emissions of toxic air contaminants from area sources has expanded to affect area sources of HAPs across the country and include disparate industries ranging from chemical manufacture and metal goods fabrication to auto body shops, heating hospitals, and emergency power.
Members can read the full February issue of EM.