Glossary
Asbestos
A fibrous mineral once widely used in building materials for insulation and fire resistance, now known to cause serious lung diseases when its microscopic fibers are inhaled.
Example:
Renovation of older buildings often requires specialized removal of asbestos to protect workers and future occupants from harmful exposure.
Clean Air Act
A U.S. federal law designed to control air pollution by setting emission standards for stationary and mobile sources and limiting the release of various pollutants.
Example:
The Clean Air Act led to the widespread adoption of catalytic converters in cars, significantly reducing vehicle emissions.
Indoor Air Pollutants
Contaminants found within buildings that can negatively impact human health, often due to poor ventilation trapping substances from building materials, cleaning products, or natural sources.
Example:
Poorly ventilated homes can accumulate indoor air pollutants like mold spores and fumes from cleaning products.
Kyoto Protocol
An international treaty that aimed to reduce greenhouse gas emissions, though its effectiveness was limited by a lack of universal participation from major emitting countries.
Example:
The Kyoto Protocol was an early attempt at global climate action, but its impact was lessened by the non-participation of some key nations.
Montreal Protocol
An international treaty designed to protect the stratospheric ozone layer by phasing out the production and consumption of numerous substances responsible for ozone depletion, such as chlorofluorocarbons (CFCs).
Example:
The success of the Montreal Protocol is evident in the healing of the stratospheric ozone layer, demonstrating effective global environmental cooperation.
Nitrogen Dioxide (NO2)
A reddish-brown gas that is a primary air pollutant, formed from the oxidation of nitric oxide (NO) and released during fossil fuel combustion. It is a key component in the formation of photochemical smog.
Example:
The brown haze often seen over cities is partly due to high concentrations of nitrogen dioxide.
Nitrogen Oxides (NOx)
A group of highly reactive gases containing nitrogen and oxygen, primarily formed during the combustion of fossil fuels. They are key precursors to photochemical smog.
Example:
Power plants and vehicle engines release nitrogen oxides, contributing significantly to urban air pollution.
Photochemical Smog
A type of air pollution formed when nitrogen oxides and volatile organic compounds react with heat and sunlight, creating a brownish haze.
Example:
Cities like Los Angeles often experience photochemical smog on hot, sunny days due to heavy traffic and geographic features.
Primary Air Pollutants
Pollutants that are released directly into the atmosphere from identifiable sources.
Example:
A car's exhaust pipe directly emits carbon monoxide into the atmosphere.
Radon
A colorless, odorless, radioactive gas that seeps into homes from the ground, primarily from the natural decay of uranium in soil and rock, posing a significant lung cancer risk.
Example:
Homeowners in certain geological areas are advised to test for radon to prevent long-term exposure and mitigate health risks.
Secondary Air Pollutants
Pollutants that form in the atmosphere when primary pollutants react with other substances, often in the presence of sunlight.
Example:
Tropospheric ozone forms when sunlight reacts with primary pollutants like nitrogen oxides and volatile organic compounds.
Thermal Inversion
A meteorological phenomenon where a layer of warm air sits above a layer of cooler, denser air near the ground, trapping pollutants below and preventing their dispersal.
Example:
Cities in valleys, like Salt Lake City, can experience severe air pollution during a thermal inversion as emissions are unable to disperse.
Tropospheric Ozone (O3)
A secondary air pollutant formed in the lower atmosphere when sunlight reacts with nitrogen oxides and hydrocarbons. It is a major component of photochemical smog and harmful to respiratory health.
Example:
On hot summer days, tropospheric ozone levels can rise, leading to 'ozone action days' warnings.
Volatile Organic Hydrocarbons (VOCs)
Organic compounds that easily become vapors or gases at room temperature, emitted from various sources including vehicles, industrial processes, and household products. They react with NOx in sunlight to form smog.
Example:
The distinct smell of gasoline or paint thinner comes from volatile organic hydrocarbons.