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.
In North America and Europe, emissions of ozone precursors such as nitrogen oxides (NOx) and volatile organic compounds (VOCs) declined by half between 2000 and 2018. However, the ozone content of the air—and thus the risk ...
Environment
Jan 29, 2026
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Escalating pollution and contamination of water and soil are emerging as serious threats to plant growth and its overall health. Plants are exposed to environmental pollutants for extended periods and exhibit changes in their ...
Plants & Animals
Dec 15, 2025
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In November 2025, Lahore, the second-largest city in Pakistan, registered a "hazardous" air quality index of 509, according to IQAir, a global air quality monitoring organization. The number speaks for itself. Eyes sting, ...
Environment
Dec 11, 2025
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Wildfire smoke causes more air pollution than current atmospheric models can predict. A new study by researchers at King Abdullah University of Science and Technology (KAUST) and the Chinese Academy of Sciences explains why ...
Earth Sciences
Oct 1, 2025
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Air pollution from secondary organic aerosols (SOA) has now become a greater problem in Chinese cities since 2013 because regulations have successfully reduced fine particulate matter (PM2.5) emitted directly from, for example, ...
Earth Sciences
Sep 2, 2025
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In a new study, crop scientists at the University of Illinois Urbana-Champaign and USDA's Agricultural Research Service show that soybeans are doubly damaged by drought and ozone pollution, both of which are increasing across ...
Plants & Animals
Aug 28, 2025
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Loretta Mickley first started thinking about smoke in the summer of 2002.
Earth Sciences
Jul 22, 2025
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Super pollutants are extremely potent climate pollutants. They include short-lived pollutants like methane, black carbon and tropospheric ozone. Super pollutants are responsible for about 45% of global warming to date. Many ...
Environment
Jun 16, 2025
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Dust particles thrown up from deserts such as the Sahara and Gobi are playing a previously unknown role in air pollution, a new study has found.
Earth Sciences
Jun 6, 2025
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A new international study led by Helmholtz Munich and the University of Rostock reveals that emissions from modern gasoline cars—despite meeting the currently strictest European emission standards EURO 6d—can become significantly ...
Environment
May 28, 2025
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