Study by ITS faculty and others finds more than 200 million people are exposed to unhealthy levels of nitrogen dioxide, mostly from transportation sources

December 5, 2023

THe Lancet cover with smoggy cityAs reported in the cover issue of Lancet Planetary Health, over 200 million people in Latin American cities are exposed to nitrogen dioxide (NO2) pollution at levels that exceed World Health Organization (WHO) guidelines, according to a recent study led by researchers at Drexel University and published in The Lancet Planetary Health. Efforts to decrease reliance on fossil fuel-based transportation and increase neighborhood greenness may reduce exposure to NO2, safeguard health, and mitigate climate change.

Though not considered a greenhouse gas, NO2 interacts with other gasses in the atmosphere to contribute to the greenhouse effect and the formation of acid rain. At the ground level, NO2 contributes to ozone formation and is strongly associated with respiratory illness and diseases such as asthma, especially among children and older adults. Indoor NO2 pollution from gas stoves and other appliances also represents an important health risk.

Members of the Urban Health in Latin America (SALURBAL) project examined levels of outdoor NO2 in over 45,000 neighborhoods across 326 cities in Argentina, Brazil, Colombia, Costa Rica, Chile, Guatemala, Mexico, and Panama. Together, these cities are home to more than 230 million people. According to the study, over 85% of these residents live in neighborhoods with ambient annual NO2 levels that are above World Health Organization (WHO) guidelines. Overall, variations in NO2 exposure were greatest across neighborhoods in the same city, rather than between different cities or countries.

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