Air Quality Permitting: Staying Minor vs. Going Major!

All facilities must review their operations to determine if they require a permit under the Clean Air Act. It is important to know the potential-to-emit (PTE) for each regulated air pollutant that can be attributed to the facility. Knowing the PTE will confirm if the facility is exempt, minor, or major for air quality permitting.

What is Potential to Emit (PTE)? It is the maximum capacity, taking into account all federally enforceable physical or operational limitations, of a source to emit a specific regulated air pollutant.

List of regulated air pollutants can be generally divided into two categories: Criteria Air Pollutants and Hazardous Air Pollutants (HAPs). Most common Criteria pollutants are nitrogen oxide (NOx), sulfur dioxide (SO2), particulate matter (PM/PM10/PM2.5), lead (Pb), carbon dioxide (CO2), and volatile organic compounds (VOC) as precursor of ozone. HAPs list is long and include 188 toxic chemicals. The HAPs list has been modified numerous times since the Clean Air Act was first passed in 1970.

The Philadelphia CMSA (Bucks, Chester, Delaware, Montgomery and Philadelphia counties) is classified as severe nonattainment for ozone. That means a facility is considered major if the PTE is greater than 25 tons per year (TPY) of VOCs or NOx. The remainder of Pennsylvania is treated as a moderate ozone nonattainment area for VOCs and NOx. That means a facility is considered major if the PTE is greater than 50 TPY of VOCs and 100 TPY of NOx. In New Jersey, the facility is considered major if the PTE is greater than 25 TPY of VOCs or NOx.

A facility can also be a major source of HAPs if it has PTE of 10 TPY of any one of the listed HAPs, or 25 TPY of total HAPs.

There are threshold quantities for other regulated pollutants but for most manufacturing facilities NOx and VOC are the important pollutants to determine major source applicability.

Understanding PTE is very important. Unless an air permit has a federally enforceable permit limit, the maximum short term air emission rate can be assumed for the entire year (i.e., 8760 hours). All facilities should document facility wide PTE with physical limitations for equipment and processes to avoid using 24 hour/day 365 days/year operating scenario assumptions. Also, note that PTE from occasionally used fire pumps and emergency generators (EGENs) count towards the facility wide totals. EPA considers 500 hours as a default assumption to calculate PTE for EGENs. So, for a 1,000-KW EGEN burning fuel oil, PTE is approximately 10.7 TPY of NOx. That is a lot if you want to stay away from 25 TPY NOx threshold.

Once the facility crosses into the major source category…it’s a whole new ballgame! Most major source permitting take about two years, need a dedicated environmental professional, and receive increased scrutiny from EPA, state agencies, and citizens.

If you have questions regarding PTE calculations or to develop a permitting strategy, call Sam Joshi at (215) 389-2811.