Classify the following pollutants into natural and manmade categories. Sewage, dust, pollen grains, chemical fertilizers, vehicular smoke, algae, pesticides, waste of animals and birds.

Sewage- Man-made

Explanation: Sewage is a manmade pollutant as it is produced by the humans and is dumped in the open.

Dust- Man-made

Explanation: Dust is produced by vehicular and industrial smoke. It is the main cause o silicosis in humans.

Pollen grains- Natural

Explanation: Pollen grains are produced by plants. These pollens can cause asthma in humans.

Chemical fertilizers- Man-made

Explanation: Chemical fertilizers are produced in industries by synthetic processes. These, when added to soil, increases the fertility of the soil.

Vehicular smoke- Man made

Explanation: Vehicular smoke consists of burnt fuels which when released into the atmosphere causes pollution.

Algae- Natural

Explanation: Algae grows in pond and rivers and decreases the oxygen content of the same. Thus, leaving fewer amounts for the fishes.

Pesticides- Man- made

Explanation: Pesticides are produced in industries by synthetic means and are used for controlling pests.

Waste of animals and birds- Natural

Explanation: These are natural wastes that are produced by birds and animals and are dumped in the open.