IB Environmental systems and societies 8.3 Urban Air Pollution Key Definitions

Contamination of the indoor or outdoor atmosphere by chemical, physical, or biological agents that modify the natural characteristics of the air.

Indicator species are organisms whose presence, absence, or abundance provides information about environmental conditions, particularly pollution levels.

$NO_x$ refers to a group of gases consisting of nitrogen dioxide ($NO_2$) and nitric oxide ($NO$).

pH measures hydrogen ion concentration, influencing chemical reactions in water.

Photochemical smog is a type of air pollution that forms when primary pollutants, such as nitrogen oxides (NOx) and volatile organic compounds (VOCs), undergo chemical reactions in the presence of sunlight, resulting in the creation of harmful secondary pollutants like peroxyacyl nitrates (PANs) and tropospheric ozone.

A temperature inversion occurs when a layer of warm air sits above cooler air near the ground, preventing vertical air circulation.

VOCs are a diverse group of organic chemicals that easily vaporize into the atmosphere.