CEMS is a database used by the Pennsylvania Department of Environmental Protection to monitor key pollutants and/or operational parameters to demonstrate compliance with emissions standards or operational criteria as stipulated in a plan approval, operating permit, or order.
The owner or operator of a source may be required to install and operate a PA DEP certified continuous emission monitoring system (CEMS) to satisfy a condition in a plan approval, operating permit, or order. CEMS data is used to demonstrate compliance with emissions and data availability standards. Generally speaking, a CEMS is the total equipment necessary for the determination, collection, and reporting of a pollutant or parameter in the applicable units of measurement. It includes the measurement interface, all necessary measurement devices and associated calibration and data handling apparatus and procedures. Systems are evaluated on an individual basis and the PA DEP does not maintain an approved list of equipment.

Most of the CEMS related activity takes place in the CEM Data Processing System (CEMDPS). Regulated entities construct work items in the CEMDPS that are submitted to the PA DEP for review. The owners or operators of PA DEP certified CEMS are required to submit emissions data to the Department through the CEMDPS each calendar quarter. The PA DEP reviews the emissions data and generates a report which is provided to the owners or operators of the regulated source. The hourly emissions data submitted by the owners or operators of the source will be reviewed by the PA DEP and ultimately provided to the public through the Open Data Porta on the www.pa.gov website. This data will be updated quarterly.

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.

EPA's Emissions Inventory System (EIS) contains information about sources that emit criteria air pollutants (CAPs) and hazardous air pollutants (HAPs). The EIS includes estimates of annual air pollutant emissions from point, non-point, and mobile sources in the 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.