Study Finds Uneven Distribution of Air Pollution in Houston

Nitrogen dioxide pollution is associated with numerous adverse health effects and is often a bellwether of other harmful pollutants’ presence.

Golfers practice at a driving range as a chemical fire at Intercontinental Terminals Company continues to send dark smoke over the Houston suburb of Deer Park on March 19, 2019. (Melissa Phillip / Houston Chronicle via AP)

HOUSTON (CN) — Houston’s air pollution is distributed unequally by race, ethnicity and income level, researchers found, such that nitrogen dioxide pollution is more than one-third worse for low-income nonwhites than it is for high-income whites in Texas’ petrochemical manufacturing hub.

“Not only are air pollution levels higher in low-income, nonwhite and Hispanic neighborhoods, but they’re also much more variable,” said Sally Pusede, an atmospheric chemist at the University of Virginia and co-author of the study. “Even though on average you have 37% higher pollution in those neighborhoods, we saw days of severe pollution where that went as high as 80-some percent.”

Pusede and 12 other scientists, led by University of Virginia doctoral candidate Mary Angelique Demetillo, used data obtained from a NASA spectrometer and satellite sensors to observe how nitrogen dioxide is distributed in Houston’s air. The group’s research, funded by a NASA award and numerous University of Virginia sources, was published Wednesday in the journal Environmental Science and Technology.

To collect data for the study, an aircraft was outfitted with a NASA instrument to observe the concentration and distribution of nitrogen dioxide, a gas produced alongside other airborne toxins during combustion. The plane would fly in the same pattern many times on different days and at different times of day to see how the distribution of pollutants fluctuated over time.

“You could get these extreme events of inequality depending on what the weather was like,”  Pusede said, explaining that stagnation conditions — very sunny days with little or no wind, for instance — corresponded to the highest levels of inequality.

Nitrogen dioxide, or NO2, pollution is associated with numerous adverse health outcomes, and it is frequently a bellwether of other harmful pollutants’ presence.

“NO2 is co-emitted with other toxic chemicals,” Pusede said. “Nitrogen dioxide is emitted from anything that involves high-temperature combustion: vehicle traffic, power plants, industrial facilities — any time when something burns really hot. Living near a roadway, for example, has been shown to be detrimental to our health. Also, NO2 is important because it is a proxy for toxic emissions from combustion. NO2 has been associated with reduced lung function, asthma, heart issues and issues in maternal health and birth.”

Houston is home to one of the largest petrochemical manufacturing industries in the world — refineries, power plants, heavy-duty diesel traffic and other high-emitting activities abound. But the scientists aren’t limiting their inquiries only to Texas.

Pusede said that future research will monitor air pollution in Denver, New York City, Chicago and Los Angeles, and noted that the group intends to monitor Houston again in 2021 to discover how air pollution inequality has changed since 2013.

Their work is also a sign of how emerging monitoring technologies and techniques can help policymakers keep tabs on air pollution in their own jurisdictions.

“One of the exciting outcomes of the work is that the satellite instrument could be used as a tool for our policymakers who are interested in eliminating environmental injustice. We can see where air pollution is higher at finer spatial scares so you can know where interventions need to occur — you can better assess policies that are being made and who’s being affected by those policies,” Pusede said. “There’s a lot of policy potential in just being able to accurately map where inequalities are occurring.”

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