Knowra Smog Smog Smog is a polluted haze of gases and particles in the atmosphere. It forms from emissions and can intensify through sunlight-driven reactions or weather conditions that trap pollution.
Photochemical smog : Air pollution formed when sunlight drives reactions among nitrogen oxides and volatile organic compounds. This sunlight-driven type develops from urban emissions on warm, bright days.
Great Smog of London : A severe air-pollution episode in London in December 1952, caused largely by coal smoke and weather that trapped it. This episode became a defining example of lethal sulfurous smog.
Air quality index : A scale that communicates how current or forecast air pollution may affect health. It translates smog-related pollutant measurements into public health guidance.
Asthma : A chronic respiratory disease in which inflamed airways narrow intermittently, causing breathing difficulty. Ozone and particles in smog can trigger symptoms and worsen asthma.
Haze : A reduction in atmospheric clarity caused by particles or droplets that scatter and absorb light. Haze describes impaired visibility; smog specifically involves polluted air and often harmful pollutants.
Sulfurous smog : A haze dominated by sulfur dioxide, sulfate particles, smoke, and moisture, historically associated with coal burning. This older form arises chiefly from sulfur-rich fuel combustion rather than sunlight-driven chemistry.
Donora smog : A deadly 1948 air-pollution episode in Donora, Pennsylvania, when an atmospheric inversion trapped industrial emissions. It exposed the danger of pollution trapped over an industrial town.
Ground-level ozone monitoring : The measurement of ozone concentrations near Earth's surface using air-quality instruments. Monitoring tracks a key smog pollutant and helps identify unhealthy episodes.
Premature mortality : Death occurring earlier than expected, often assessed in population studies of environmental hazards. Long-term exposure to polluted air is associated with increased premature deaths.
Fog : A cloud of tiny water droplets near the ground that reduces visibility. Fog is a meteorological water-droplet phenomenon, though pollution can mix with it.
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