EPA's Emissions Inventory System (EIS) contains information about sources that emit criteria air pollutants (CAPs) and hazardous air pollutants (HAPs). This data contains the facility information for Pennsylvania counties. EPA collects information about emission sources and releases an updated version of the NEI database every three years. The data made available in the NEI are used for air dispersion modeling, regional strategy development, setting regulations, air toxins risk assessment, and tracking trends in emissions over time. The data derived in the State of Pennsylvania is published and searchable online on the www.pa.gov website. This data will be updated annually for the prior calendar year in the first Quarter of the following year.