Air Quality and Greenhouse Gas Measurements

As the United States works towards reducing greenhouse gas (GHG) emissions, it is important to quantify current emissions to develop achievable targets. By monitoring GHG measurements we can determine emissions sources, evaluate existing emissions inventories, and investigate long-term trends of GHG emissions and their impact drivers. ARL’s overall goals are to provide evidence-based science to policy-makers through the analysis of hyper-local in-situ measurements and to improve understanding of the key components that form air pollution: emissions, meteorology and chemistry.


Cessna 402B research craft and the Air Resources Car. Both carry similar instruments so measurements are corroborated when they are deployed in the same area at the same time.

ARL uses several sources for collecting data on air pollution, including by ground station, airplane and car. Air quality monitoring sites in Beltsville and near I-95 in Maryland provide 24/7 measurements in the Washington area. A Cessna 402B research aircraft has been used to collect aircraft measurements of GHGs and air pollutants, including CO2 and methane as well as ozone and particulate matter and their precursors. ARL also uses the NOAA Air Resources Car (ARC) to find and measure sources of GHG and air pollutants.

The ARC goes on routine trips in the Baltimore-Washington region, up through the northeast corridor. However, NOAA’s ARC is also used during field campaigns in other areas. This summer, the car will join the AiRMAPS campaign in the Colorado Front Range and Salt Lake City, Utah. In addition to the ARC, ARL is also deploying instruments on the NOAA Twin Otter to measure in-situ GHGs and air pollutants.

In the coming years, ARL will be involved in four more AiRMAPS campaigns.

ARL will be involved in the upcoming AiRMAPS campaigns:



2026AiRMAPS Southwest

2027AiRMAPS West

2028AiRMAPS North

Previous campaigns ARL has participated in include:


2022Marcellus Flights




View of some of the instruments mounted on the Cessna 402B research aircraft.

Left to Right: Ground monitoring station in Beltsville, MD; Air Resources Car riding on the ferry at Port Jefferson in Long Island, NY; ground monitoring station near the I-95 roadway in Maryland.