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• Electrical Usage – Emissions associated with the onsite generation of electricity using coal, oil, or natural gas; 

• Refrigerants – A range of chemicals used for refrigeration and air conditioning that are comprised of substances possessing high global warming characteristics (e.g., Freon, chlorofluorocarbons, etc.); and 

• Waste Management – Emissions associated with the solid waste gene rated and the recycling and solid waste disposal practices employed by the airport. 

## 3.2. Pollutants of Concern 

There are a variety of air pollutants associated with aviation-related activities that can potentially have an impact on the environment. This section identifies and discusses these pollutants which consist of EPA’s criteria pollutants and their precursors, GHGs, and HAPs. 

## 3.2.1. Criteria Pollutants 

As discussed in Section 2 ( Regulatory Framework ), the EPA has established the NAAQS under the CAA for six common air pollutants known as “criteria pollutants”. These air pollutants consist of CO, Pb, NO $_{2}$, O$_{3}$, PM, and SO $_{2}$. The criteria pollutants are generally described in Table 3-1 ( EPA Criteria Air Pollutants ). 

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