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.
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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Global warming will likely hinder our future ability to control ground-level ozone, a harmful air pollutant that is a primary component of smog, according to a new MIT study.
Earth Sciences
May 22, 2025
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The Los Angeles region has some of the most polluted air in the United States, failing to meet standards set by the Environmental Protection Agency for the last decade. Now, Caltech researchers have quantified the levels ...
Environment
May 21, 2025
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Despite decades of progress in reducing air pollution, Los Angeles is still the nation's smoggiest city, according to a report released on April 23 by the American Lung Assn.
Environment
Apr 24, 2025
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A new study has revealed a significant shift in the sources of nitrogen oxides (NOx) pollution in central London, with gas boilers used for heating now identified as the primary contributor.
Environment
Apr 10, 2025
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