nitrogen oxides

DISCOVER-AQ: Tracking Pollution from the Skies (and Space) Above Denver

NASA four-engine turboprop P-38 takes to the sky

NASA four-engine turboprop takes to the sky for clean air science.


EPA scientists have teamed up with colleagues from NASA to advance clean air research. Below is the latest update about that work. 

Denver is the last of four cities in a study by EPA and partners that will give scientists a clearer picture of how to better measure air pollution with instruments positioned on the earth’s surface, flying in the air, and from satellites in space.

The NASA-led study is known as DISCOVER-AQ, and is being conducted July 14 to August 12 in Denver.  The research began in 2011 with air quality measuring conducted in the Baltimore-Washington, DC, area followed by a field campaign in California’s San Joaquin Valley and Houston in 2013.

Right now, monitoring for pollutants such as sulfur dioxides, nitrogen oxides, particulates and ozone is done by ground-based systems strategically located across the U.S. to measure air quality in metropolitan areas and on a regional basis. Researchers want to tap satellite capabilities to look at pollution trends across wide swaths of the country.

“The advantage of using satellites is you can cover a wider area,” said Russell Long, an EPA project scientist.  “But right now, it’s hard for satellites to determine what air pollutants are close to the ground.”

Satellites could be an important tool for monitoring air quality given the large gaps in ground-based pollution sensors across the country and around the world. Improved satellite measurements should lead to better air quality forecasts and more accurate assessments of pollution sources and fluctuations.

However one of the fundamental challenges for space-based instruments that monitor air quality is to distinguish between pollution high in the atmosphere and pollution near the surface where people live.

Ground-based air sensor station

Ground-based air sensor station from the study’s previous Baltimore and Washington area component.

The ground-based sensor readings taken by EPA and other partners in DISCOVER-AQ will be compared to air samples taken by NASA aircraft flown between 1,000 and 15,000 feet in the skies above the Denver metropolitan area. EPA scientists are using the opportunity during the DISCOVER-AQ study to also test various types of low-cost and portable ground-based sensors to determine which ones work the best.

“Our goal is to evaluate the sensors to see how well they perform,” Long said. “By including more sensors it increases our understanding of how they perform in normal monitoring applications and how they compare to the gold standard (for measuring air quality) of reference instrumentation.”

New sensors could augment existing monitoring technology to help air quality managers implement the nation’s air quality standards.

Another big part of EPA’s involvement in DISCOVER-AQ is working with schools and academic institutions to develop a robust citizen science component for pollution monitoring. In Houston, hundreds of student-led research teams all worked to test the air pollution technology by taking regular readings at their schools when NASA aircraft flew overhead.

In Denver, most schools are out for the summer, but EPA researchers will be partnering with the Denver Museum of Nature and Science to share what they are doing in DISCOVER-AQ with the general public.

Long says he is also working with University of Colorado Boulder to look at a unique three-dimensional model of air pollution in the great Denver area. The end result of DISCOVER-AQ will be a   global view of pollution problems, from the ground to space, so that decision makers have better data and communities can better protect public health.

Learn More

DISCOVER-AQ in EPA Science Matters


NASA Discover-AQ Mission

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

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Schools, Children’s Health and the Environment

By Shao Lin and Christine Kielb

How do environmental hazards and policies affect children’s health and school performance?

Group photo of health schools research team

Healthy Schools Group, from L to R: Melissa Frisbee , Nazia Saiyed, Christine Kielb, Cristian Pantea, Amanda St. Louis, Michele Herdt-Losavio, Neil Muscatiello, Shao Lin.

Thanks to support from the EPA Science To Achieve Results (STAR) program, we explored those questions. Our project is the first to addresses multiple aspects of environmental health and schools, such as developing indicators related to school locations, and how to develop methodologies for assessing and improving school health.

With EPA support, we are: 1) developing and enhancing Environmental Public Health Indicators (EPHI) representing environmental hazards, children’s school performance, and health; 2) exploring new methodologies for assessing exposure sources; 3) assessing how school environments, along with location and socio-economic status affect children’s health; and 4) evaluating the effectiveness of efforts to protect children’s environmental health in New York, such as the New York State Clean air School Bus Program and school bus idling regulations.

EPA support also enabled us to extend or continue our previous activities, including: tracking how school building conditions and asthma hospitalizations change over time in New York; surveying school nurses, custodians, district facility directors, and teachers to identify environmental problems—and potential solutions—facing schools; and examining how the surrounding neighborhood, specifically a school’s proximity to facilities such as hazardous waste sites, major roads, or airports might increase childhood asthma risk. We also assessed the impacts of healthy school characteristics related to indoor air quality, ventilation, cleanliness, thermal comfort, lighting and acoustics on student attendance, academic performance, and respiratory health.

Image of a schoolWe found some important results. For example, our work showed an association between missed school days and certain poor conditions in the school: visible mold, humidity, poor ventilation, and vermin. Having six or more individual such building-related problems was also associated with student absenteeism. Further, these associations were strongest among schools in lower socioeconomic districts, and in schools attended by younger students. We also found district-level childhood asthma hospitalizations to be related to poor condition of roofing, windows, exterior wall, floor finishes, and boiler or furnace.

When looking at air quality, we found that the control policy for nitrogen oxides (NOx) may have had a positive impact on both state-wide and regional air pollution levels and respiratory health. The positive effect varied by children with different types of respiratory diseases, region, and socio-demographic characteristics.

Our EPA-supported research is providing important data and information, informing our work developing and implementing a sustainable school environmental health program for New York State. We have shared our findings with a Steering Committee consisting of approximately 50 key school environmental health stakeholders, including superintendents, facilities managers, teachers, state agencies, physicians and advocacy groups, and have been working on plans to address existing and emerging environmental problems challenging schools. With these efforts well under way, we fully expect our findings to lead to healthier students, teaches, and other school occupants throughout New York.    

About the Authors: EPA grantee Dr. Shao Lin (MD, Ph.D.), has more than 20 years of experience directing environmental studies, including climate/weather factors, air pollution, heavy traffic exposure, residential exposure to urban air pollution, health effects among New York City residents living near Ground Zero, and a series of school environmental health projects.

Christine  Kielb has worked as an epidemiologist in the area of school environmental health since 2002, and has coordinated various school environmental health projects. She has played a major role in developing, conducting and analyzing surveys of school nurses, custodians facilities managers, and teachers regarding school environments and health. 


Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.