Air Pollution Notes

Air pollution is a global issue because the atmosphe re surrounds the entire planet.
Air pollution is defined as the introduction of chemicals, particulate matter, or microorganisms into the atmosphere at concentrations high enough to harm plants , a
nimals, and materials or alter ecosystems.

These pollutants are often released through the combustion of fossil fuels.
Sulfur Dioxide (SO2):
- Sulfur is present in varying amounts in plants and animals, and : consequently, in fossil fuels derived from their remains.
Nitrogen Oxides (NOx):
- Can exist as either nitrogen oxide (colorless, odorless) or nitrogen dioxide (pungent, reddish-brown).
- These forms can easily transform from one to the other in the atmosphere.
Carbon Oxides:
- Carbon monoxide (CO) is a common emission from vehicle exhaust and other combustion processes.
- Carbon dioxide (CO2) released by burning fossil fuels has become a major pollutant.

A VOC is an organic compound that evaporates at typical atmospheric temperatures and is a precursor to ozone.
Many VOCs are hydrocarbons.
Formed by the evaporation of fuels, solvents, paints, and the incomplete combustion of fuels like gasoline.

A class of air pollutants formed as a result of sunlight acting on chemical compounds like nitrogen oxides.
Ozone (O3):
- A type of photochemical oxidant.
- A secondary pollutant made up of three oxygen atoms bound together.
- Can be beneficial or harmful depending on its location (stratosphere vs. troposphere).
In the presence of sulfur and nitrous oxides, photochemical oxidants can worsen smog.

Smog is a type of air pollution that is a mixture of oxidants and particulate matter.
Two types of smog:
- Photochemical smog:
  - Dominated by oxidants such as ozone.
  - Also known as Los Angeles-type smog or brown smog.
- Sulfurous smog:
  - Dominated by sulfur dioxide and sulfate compounds.
  - Also known as London-type smog, gray smog, or industrial smog.

Primary pollutant:
- A polluting compound that comes directly from a smokestack, exhaust pipe, or natural emission source.
- Examples: CO, CO2, SO2, NOx, and most suspended particulate matter.
Secondary pollutant:
- A primary pollutant that has undergone transformation in the presence of sunlight, water, oxygen, or other compounds.
- Examples: O3, sulfate, and nitrate.
The transformation from primary to secondary pollutants requires factors such as sunlight, water (clouds), and appropriate temperatures.