Increasingly, government agencies and concerned community groups are asking airport operators to provide information to enable an assessment of the health impacts of toxic emissions from aircraft and other airport-related sources. A key component of potentially toxic airport-related emissions, affected by the National Environmental Policy Act (NEPA) and state-level environmental programs, is Hazardous Air Pollutants (HAPs). Unlike criteria air pollutants (particle pollution, ground-level ozone, carbon monoxide, sulfur oxides, nitrogen oxides, and lead), information on the emission, transformation, and transport of aviation-related HAPs and their health impacts is rudimentary. Without a better understanding of aviation HAP emissions, airport operators are unable to develop accurate inventories and are left with little guidance on how to provide state and local constituencies with information they need.
An ACRP study was funded in 2007 to examine and identify gaps in current research on airport-related HAP emissions and to recommend and prioritize additional research to help understand potential impacts. This study, ACRP Project 02-03, "Aircraft and Airport-Related Hazardous Air Pollutants: Research Needs and Analysis," concluded that an important source of airport-related HAP compounds at most commercial airports is idling jet engines and that understanding the scale and character of this emission source is, therefore, a high priority to the airport community. It recommended a targeted research effort to document the contribution of idling jet engines to HAP emissions.
Testing from earlier APEX (Aircraft Particle Emissions eXperiment) measurement campaigns has confirmed that HAP emissions of modern jet engines are relatively small at power settings greater than idle; however, less is known about HAP emissions from aircraft at idle power settings. It is expected that these emissions will vary as a function of thrust setting, environmental variables (especially temperature), and engine type. Therefore, to estimate airport HAP emissions properly, it is critical to understand the rate of HAP emissions at low power settings as a function of ambient conditions.
The objective of this project is to design and implement a test program to measure gaseous HAP emissions from in-production jet engines operating at a range of idle settings and ambient temperatures. The primary research objective of this program would encompass measurements of total hydrocarbons and speciated hydrocarbons, including HAPs, within the exhaust plume at a reasonable proximity of the engine nozzle to capture emissions prior to condensation of volatile gasses. The secondary research objective would be to include measurements at a downstream location where the plume has cooled to near-ambient temperatures.
Status: Published as Report 63, May 2012