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NASA is using data intended for weather and climate research to help pinpoint how environmental factors such as aerosol levels in the atmosphere impact cardiovascular health. Aerosols are solid and liquid particles suspended in the atmosphere, and can occur naturally or get emitted by human activities such as burning fossil fuels.

Scientists measure aerosols, also called particulate matter (PM), by their size. The smallest particles -- less than 2.5 microns in diameter (PM2.5) -- are the worst for human health because they can make their way into the lungs or bloodstream and exacerbate cardiovascular problems, especially in very young and elderly populations.

The ability to detect these microscopic particles (often found in smoke and haze) is helping public health researchers better document the health risks for the general population and specifically at-risk populations.

Dr. Yang Liu, a researcher at Emory University, first realized that NASA satellite data could enhance public health tracking while attending a 2007 NASA workshop where scientists from the Center for Disease Control (CDC) presented an overview of a newly formed tracking network.

The National Environmental Public Health Tracking Network was created in 2002 as a cooperative program to find and document links between environmental hazards, such as aerosols, and diseases. The network uses ground-based air pollution data provided by the Environmental Protection Agency (EPA), and disease information from the CDC to monitor and distribute information about environmental hazards and disease trends, as well as develop a strategy to combat these trends.

Since the workshop, Dr. Liu has been working with NASA to integrate data from two instruments, the Multi-angle Imaging SpectroRadiometer (MISR) (onboard the NASA Terra satellite) and the Moderate Resolution Imaging Spectroradiometer (MODIS) (onboard NASA's Terra and Aqua satellites) into the tracking network. Both MISR and MODIS are used to monitor tropospheric aerosols.

"NASA satellites allow faster observations with a wider view to increase our understanding of the connections between PM 2.5 and illnesses, " said Liu "We can essentially provide more timely estimates of harmful aerosol concentrations."

Until recently, ground-based air quality monitoring has been the only data source for estimating exposure to aerosols. However, even in the U.S., the networks are spread out and the coverage is limited by high operating costs. Using NASA satellite information, federal, state, and local agencies will be better prepared to develop and evaluate effective public health actions.

Liu explains that "Satellites have both wide spatial coverage and long mission lives, so a satellite measuring the quantity of small aerosol particles over a larger area can supplement ground-based measurements and do so over a longer period of time."

NASA's contribution to public health does not stop there, however. NASA also has been working with researchers at the University of Alabama at Birmingham (UAB) to determine how atmospheric conditions contribute to cardiovascular disease in African Americans. Past research has shown that group to have a higher risk of contracting cardiovascular disease, hypertension, and other environmentally related diseases.

UAB has been working for six years on a public health study called Reasons for Geographic and Racial Differences in Stroke (REGARDS). Funded by the National Institutes of Health, REGARDS researchers recorded blood pressure, took blood samples, and asked detailed health questions of more than 30,000 people, particularly African Americans, between January 2003 and October 2007. The study focused on the so-called 'Stroke Belt', the area in the southeastern U.S. where incidents of stroke are 1.5 times the national average.

The REGARDS program is now working with colleagues at NASA to integrate satellite data on temperature, humidity, particulate matter in the air, and other environmental elements, to understand the connections between the atmosphere and human health.

"We can merge the REGARDS data with our data from MODIS," said Mohammed Al-Hamden, a co-lead on the project and a scientist at NASA's Marshall Space Flight Center. "We examine the statistical relationships between these diseases and the air quality and climate where these people live. With the wide spatial coverage of satellite measurements, we can better help health officials with environmental alerts and health recommendations."

Bill Crosson, the other NASA lead on the REGARDS project says the value of integrating NASA data is "that the data comes quickly and more frequently -- daily instead of weekly so we can provide it to the people who really need it."

The regional study has been so successful that it has recently expanded to the entire nation, with the information that NASA provides being integrated into a CDC database of public health records, called the Wide-ranging Online Data for Epidemiological Research (WONDER). NASA and UAB researchers are expanding the subject of the study along with its geographic range. Researchers are now exploring the connection between harmful particulate matter and cognitive decline, including memory, attention span, as well as reading listening comprehension.

With these two NASA-sponsored projects, public health officials are improving air quality forecasts, preparing hospitals for air quality-related health problems, and perhaps preventing health problems in the future by warning the public about the potentially harmful effects of aerosols.

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