Photochemical air pollution is an atmospheric phenomenon in which primary pollutants, principally nitrogen oxides (NOx) and volatile organic compounds (VOCs), undergo sunlight-driven photochemical reactions to form a complex mixture of secondary pollutants. Key products include ozone (O₃) in the troposphere, peroxyacyl nitrates (PANs), aldehydes, organic nitrates, and secondary organic aerosols. These reactions are initiated by NO₂ photolysis, generating ozone and radical species (e.g., OH, HO₂, RO₂) that propagate non-linear reaction chains. Photochemical air pollution is characterized by strong diurnal and seasonal patterns and is sensitive to precursor emissions, meteorology, and atmospheric oxidizing capacity.
An increase in pollution from wildfires and heat waves risks undermining international efforts to improve air quality and protect human and ecosystem health, according to a new report from the World Meteorological Organization ...
Earth Sciences
2 hours ago
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Scientists have directly observed a fleeting chemical reaction that creates a key ingredient in urban smog. The research offers insight into the earliest stages of pollution formation and could help improve air quality forecasting ...
Environment
Aug 26, 2026
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As wildfire smoke plumes travel thousands of miles, sunlight and atmospheric chemistry bleach their color, strip away their campfire aroma and add them to the mix of urban smog.
Environment
Aug 25, 2026
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Amid current heat waves, urban greening is once again moving to the center of public debate. Greener cities are generally expected to have cleaner air because trees capture airborne particles, absorb gaseous pollutants and ...
Environment
Aug 19, 2026
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Taiwan's air has gotten measurably cleaner over the past decade, yet in many towns the hazy, milky-white sky that blurs mountains and city skylines has not cleared at the same pace. A research team led by Prof. Ta-Chih Hsiao ...
Environment
Aug 12, 2026
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The effects of climate change extend far beyond rising temperatures. As forests and other vegetation respond to a warming world, they also change the amount of biogenic emissions released into the atmosphere, influencing ...
Earth Sciences
Aug 5, 2026
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Two-thirds of the European Union's population may have been exposed to harmful levels of ozone pollution during last month's record-breaking heat wave, a report exclusively shared with AFP warned Thursday.
Environment
Jul 9, 2026
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Climate change will profoundly alter the dynamics of sea and land breezes in the Barcelona metropolitan area, trapping larger amounts of air pollutants over coastal areas and increasing health risks for millions of people. ...
Environment
Jun 11, 2026
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The TEMPO mission helped scientists track morning nitrogen dioxide that contributed to afternoon ozone along the New York–Washington corridor in May 2026. More than 35 million people live along the New York–Washington corridor ...
Environment
Jun 11, 2026
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For decades, the United States made steady progress in reducing surface ozone pollution, the main ingredient in smog. But that progress—made as vehicles, industries, and power sources became cleaner—is increasingly being ...
Environment
Jun 5, 2026
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