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.
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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78
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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96
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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27
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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71
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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35
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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32
As the adoption of cleaner-burning engines and electric vehicles drives fossil fuel emissions lower, scientists have discovered that a surprising pollution source is playing a significant role in cooking up ozone in the air ...
Environment
Mar 13, 2025
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39
Sunlight has a major influence on chemical processes. Its high-energy UV radiation in particular is strongly absorbed by all materials and triggers photochemical reactions of the substances present in the air. A well-known ...
Optics & Photonics
Apr 10, 2024
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72
Typically, beautiful white wall paint does not stay beautiful and white forever. Often, substances from the air accumulate on its surface. This can be a desired effect because it makes the air cleaner for a while—but over ...
Nanomaterials
Mar 25, 2024
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