Community-Focused Air Monitoring: Geospatial Measurement of Air Pollution (GMAP)

What is GMAP?
GMAP is a mobile air monitoring vehicle designed to measure the concentration of multiple air pollutants, many in real time.  The vehicle is equipped with gas and particulate analyzers, various meteorological instruments, and high-precision GPS.  These instruments are collectively referred to as GMAP, which stands for “geospatial measurement of air pollution,” and the data collected by the GMAP vehicle can be used to better understand local air quality. The GMAP vehicle provides the benefits of a “Next Generation Compliance” tool and further DEEP’s commitment to protecting air quality and public health and promoting environmental justice. GMAP data can be plotted on a map or over satellite imagery, as below.

Satellite imagery displaying monitoring results from the GMAP vehicle.

Example of GMAP results

What can GMAP do?

GMAP can help DEEP better understand air pollution at a hyperlocal level. The GMAP enables DEEP to:    

  • Investigate air quality concerns
  • Measure the concentration of many different pollutants
  • Pull ambient air samples for laboratory analysis
  • Identify sources of pollution that have gone undetected using traditional inspection techniques
  • Fill the gap between our ambient air monitoring stations and emission testing of known sources
How will DEEP use GMAP?

DEEP will use GMAP to conduct emission surveillance throughout the state, with an emphasis on surveillance in environmental justice and historically overburdened communities. 

DEEP will also use the GMAP vehicle as an inspection tool to screen stationary sources with a high potential for fugitive emissions (i.e., air pollution that does not pass through a smokestack) or with short smoke stacks and the potential to impact the community (i.e., poor dispersion parameters).  This will help DEEP understand how such sources impact local air quality.

How will DEEP use the data from GMAP?

Before conducting GMAP runs, DEEP will reach out to community groups in the area to better understand residents’ air quality concerns.  After analyzing data from GMAP runs, DEEP intends to provide an opportunity to share what we’ve learned with the community.

Where will GMAP be used?

The decision of where to deploy the vehicle is based on a number of factors, many of which are described in the Department’s GMAP Targeting Criteria.  

DEEP is committed to prioritizing GMAP monitoring in environmentally overburdened or distressed communities, which are disproportionately impacted by the harmful effects of pollution.



Note that all data is subject to a complex review and analysis.  Therefore, it may take several months for the final results of a GMAP monitoring project to be compiled and posted.

Why is the GMAP vehicle in my neighborhood?

A location may be selected due to DEEP priorities or an environmental justice initiative. Please note that the presence of the vehicle in an area does not necessarily mean there is an air quality problem or any threat to public health or the environment.


Which pollutants does the vehicle measure?

The GMAP vehicle has the ability to measure the following pollutants, though not all pollutants will be measured during every trip:


Criteria Pollutants/Precursors

Greenhouse Gases

  • Benzene
  • Toluene
  • Ethylbenzene
  • m-, o-, and p-Xylene
  • Formaldehyde
  • Styrene
  • 1,3-Butadiene
  • Black carbon
  • Ammonia
  • Nitrogen oxide
  • Nitrogen dioxide
  • Ozone
  • Total VOC (as isobutylene)
  • Sulfur dioxide
  • Coarse particulate matter
  • Fine particulate matter
  • Ammonia
  • Carbon dioxide
  • Methane
  • Black carbon

*On an as-needed basis, the Department will be able to draw Summa canister samples and analyze for individual constituents.

Who is operating the vehicle? 

The vehicle is operated by DEEP staff who work in the Bureau of Air Management, Enforcement Division.  Staff has received extensive training on safe operation of the vehicle and its equipment.

Is it safe to be near the vehicle?

Yes.  The vehicle does not emit any harmful substances or pose any danger to the public beyond that of a typical passenger vehicle.  Please exercise the same level of caution you would when in the vicinity of any passenger vehicle.

What if GMAP detects and air quality problem in an area?

DEEP staff carefully reviews and analyzes the data gathered during GMAP monitoring activities.  If staff finds elevated levels of air pollution, additional GMAP monitoring may be conducted and/or additional investigation may be performed using other equipment or techniques.  If a specific source of pollution is identified, DEEP will address the issue to ensure that the source is compliant with all applicable state and federal air pollution control laws.


An image showing satellite imagery and air pollution monitoring visualized in 3D.

Example of GMAP results.  Photo credit: EPA


Who can I contact for additional information?

For additional information, please contact Lakisha Stephenson of the Compliance Analysis and Coordination Unit at (860) 424-3729 or


Related Links: 

GMAP Monitoring Projects GMAP Targeting Criteria | GMAP Fact Sheet | Informacion especifica de GMAP| GMAP Press Release | Environmental Justice