Under the Clean Air Act, what must industries implement to control air emissions?

Industries must implement an emissions control technology or system to manage and reduce air emissions in compliance with the Clean Air Act. This requirement is central to the Act's purpose, which is to protect air quality and public health by setting national standards for air pollutants. Emissions control technologies can include various methods and systems, such as scrubbers, filters, electrostatic precipitators, and other advanced engineering solutions that directly address the release of harmful substances into the atmosphere.

While public relations programs, emergency response protocols, and sustainable transportation policies are all important aspects of environmental management and safety, they do not directly fulfill the specific requirements set out by the Clean Air Act regarding air emissions. Public relations programs might help raise awareness about emissions practices, emergency response protocols are crucial for managing accidental releases, and sustainable transportation policies can support lower emissions overall; however, none of these options directly implement the required technology or systems to control emissions as mandated by the legislation. Thus, implementing an emissions control technology or system is the most critical factor for compliance under the Clean Air Act.