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Science

Humans and their environment

Air pollution

Factories can cause air pollution

The most common source of air pollution is the combustion of fossil fuelsfossil fuels: Fuels such as coal, oil and natural gas, made from the remains of ancient plants and animals.. This usually happens in vehicle engines and power stations.

Some common air pollutants and their effect

pollutanttypical effect
smoke Deposits soot on buildings and trees, causing them damage. Permeates the air, making it difficult for living creatures to breathe.
carbon monoxidepoisonous gas
carbon dioxidegreenhouse gas that contributes to global warming
sulfur dioxidecontributes to acid rain

Indicators of air pollution

Lichens are plants that grow in exposed places such as rocks or tree bark. They need to be very good at absorbing water and nutrients to grow there, and rainwater contains just enough nutrients to keep them alive. Air pollutants dissolved in rainwater, especially sulfur dioxide, can damage lichens, and prevent them from growing. This makes lichens natural indicators of air pollution. For example:

  • bushy lichens need really clean air
  • leafy lichens can survive a small amount of air pollution
  • crusty lichens can survive in more polluted air

In places where no lichens are growing, it's often a sign that the air is heavily polluted with sulfur dioxide.

Back to Evolution and environment index

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