7.3 Impact of Atmospheric Pollution

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1. Smog and Its Effects on Human Health

What is smog?

Smog is a type of thick, hazy air pollution that forms in the atmosphere, especially over cities. The word comes from combining "smoke" and "fog." It is a visible sign that the air is heavily polluted and harmful to breathe.

Smog forms when pollutants — mainly from car exhausts, factory emissions, and burning of fossil fuels (coal, oil, and gas) — mix together in the air. Sunlight can cause some of these pollutants to react with each other, making a particularly dangerous type called photochemical smog (smog created by sunlight triggering chemical reactions).

Effects of smog on human health

Smog contains harmful gases and tiny particles that enter the body when you breathe. Here is what it can do:

• Breathing problems — Smog irritates the lungs and airways. People with asthma (a condition that makes breathing difficult) are especially at risk and may have severe attacks. Even healthy people can develop coughing, wheezing (a whistling sound when breathing), and a tight chest.
• Worsening of existing conditions — People who already have lung diseases (such as bronchitis, which is inflammation of the airways) or heart disease are much more likely to be seriously harmed by smog.
• Eye, nose, and throat irritation — Smog causes stinging, watery eyes, a runny nose, and a sore throat.
• Long-term lung damage — Breathing in smog regularly over many years can permanently damage the lungs and reduce their ability to work properly.
• Increased risk of death — In severe smog events, especially among elderly people and those with existing health problems, smog can be life-threatening.