Tools: Virtual Plant Tour

Regulatory Information | Best Practices | Case Studies

Regulatory Information

Stop 04: Vent/Flare

Highlighted Topic:  Clean Air Act Overview

Tour Stop 04

One of the major environmental laws affecting chemical facilities is the Clean Air Act (CAA).  The Act applies to air emissions not only from process vents, but also from boilers, steam vents, and flares.  It also covers "fugitive" emissions from piping, storage and transfer activities, and even construction and remediation.  You also need to check for coverage under state or regional air regulations, since states and regional authorities have important responsibilities under the Clean Air Act, and can impose additional requirements.

The CAA regulates emissions that affect general air quality (such as sulfur dioxide or particulates), as well as hazardous or toxic chemical emissions (benzene, MEK, and other VOCs, etc.)  The CAA can be enforced by EPA, or by state or regional air agencies that have been delegated authority by EPA.

Three major components of the Clean Air Act that will affect chemical facility process operations are:

  • regulation of criteria pollutants under the National Ambient Air Quality Standards (NAAQS).   These standards cover the ambient regional air quality, and address certain key pollutants such as particulate matter (PM), sulfur oxides, and VOCs.   Each facility will have a permit covering these pollutants that addresses major sources and any changes to emissions levels.
  • regulation of certain source emissions under the New Source Performance Standards (NSPS).  These standards are source-based, and set certain operation and reporting requirements for the specific sources.
  • regulation of certain hazardous air pollutants under the National Emissions Standards of Hazardous Air Pollutants (NESHAPS).  The NESHAPS standards are pollutant-based, and generally require the implementation of "Maximum Achieveable Control Technology" or MACT that would be applicable to whichever sources generate the pollutant. 

By its nature, a chemical plant is likely to be fully regulated under the CAA, with many units being covered by multiple regulations (e.g., a reactor would be covered by NSPS standards for reactors, as well as various NESHAPS standards for the specific pollutants present).

Note that all air requirements for a facility will likely be consolidated into one operating permit document called the Title V ( or "Title Five") permit, which establishes emissions levels, and monitoring and reporting requirements.  In addition, major individual sources will also be subject to specific permits (e.g., reactors, incinerators, etc.), which often require installation of a certain control technology as well as continuous emissions monitoring, and recordkeeping and reporting requirements.

Other Regulatory Issues:

In addition to air emissions, vents, flares or other stacks are potential sources of hazardous waste and wastewater (e.g., in the case of any wet scrubbing).