Continuous Emission Monitoring, 3rd Edition

CHAPTER 13MONITORING HAZARDOUS AIR POLLUTANTS

Hazardous air pollutants, also known as toxic air pollutants or “air toxics,” are known to cause cancer or other serious health effects. For these pollutants, the emission control criteria, emission limits, performance test requirements, and continuous monitoring rules are found primarily in the U.S. Code of Federal Regulations under 40 CFR 63. These are also called the “MACT” standards, which are based on the emission control achieved by the single best controlled plant within a source category. This level of control is called “maximum achievable control technology” or “MACT” and must be met by any new and reconstructed plants. In this sense, the standards are based initially on what can be achieved by the best available control technology and not on the health risks of the pollutants.

PART 61 NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS (NESHAPS)

Air toxics were first required by the 1970 Clean Air Act, where health‐based standards were developed. These earlier “national emission standards for hazardous air pollutants” (NESHAPs) were published in 40 CFR 61, and in contrast to the Part 63 MACT standards, are based on health risks rather than the effectiveness of emissions control technology (U.S. EPA 2020i). However, standards for sources of vinyl chloride, benzene, and arsenic were only developed in the Part 61 NESHAPs program for hazardous air pollutants.

Congress directed EPA in §112(c) of the 1990 Clean Air Act ...