Glossary
Acid Rain
Precipitation, such as rain, snow, or fog, that is unusually acidic due to atmospheric pollution, primarily from sulfur dioxide and nitrogen oxides.
Example:
Forests in the northeastern United States have suffered damage from acid rain caused by industrial emissions.
Industrial Smog
A type of air pollution primarily formed from industrial emissions, especially from burning coal, characterized by a thick, yellowish haze.
Example:
During the Industrial Revolution, cities like London were frequently blanketed in dense, choking industrial smog from coal fires.
Nitrogen Dioxide ($NO_2$)
A reddish-brown gas that is a major air pollutant, formed from the oxidation of nitric oxide, and plays a central role in the formation of photochemical smog.
Example:
The brownish haze often seen over cities is partly due to the presence of nitrogen dioxide in the atmosphere.
Nitrogen oxides ($NO_x$)
A group of highly reactive gases containing nitrogen and oxygen, primarily emitted from vehicle exhaust and industrial processes, crucial for photochemical smog formation.
Example:
Cars and trucks are major sources of nitrogen oxides, which react with sunlight to create urban haze.
Particulate Matter
Tiny solid particles or liquid droplets suspended in the air, originating from various sources like combustion and industrial processes, contributing to smog and respiratory issues.
Example:
Fine particulate matter from diesel exhaust can penetrate deep into the lungs, causing significant health problems.
Photochemical Smog
A type of air pollution formed when sunlight reacts with nitrogen oxides and volatile organic compounds in the atmosphere.
Example:
Los Angeles often experiences photochemical smog on hot, sunny days due to heavy vehicle traffic and abundant sunlight.
Smog
A type of air pollution that appears as a hazy mixture of smoke and fog, significantly reducing visibility.
Example:
On a particularly still, hazy day, the city skyline was barely visible through the thick layer of smog hanging over it.
Sulfur dioxide ($SO_2$)
A colorless gas with a pungent odor, released primarily from the burning of fossil fuels, and a main component of industrial smog.
Example:
Power plants burning high-sulfur coal release large amounts of sulfur dioxide, contributing to acid rain and industrial smog.
Tropospheric Ozone ($O_3$)
Ozone found in the lower atmosphere (troposphere), which is a harmful air pollutant and a key component of photochemical smog.
Example:
On hot summer days, high levels of tropospheric ozone can trigger asthma attacks and respiratory problems in sensitive individuals.
Volatile Organic Compounds (VOCs)
Organic chemicals that have a high vapor pressure at ordinary room temperature, released from various sources including vehicles, industrial processes, and natural vegetation.
Example:
The distinct smell of gasoline comes from volatile organic compounds evaporating into the air.