Particulates as atmospheric pollutants

Particulates are tiny solid particles or liquid droplets suspended in the air. When their amount in the air increases, they can affect both human health and the amount of sunlight reaching the ground.

Particulates and health

Small particulates can be breathed into the lungs, where they may irritate or damage the respiratory system. Higher amounts of particulates in the air therefore increase the risk of respiratory problems.

Particulates and global dimming

Particulates scatter or absorb sunlight as it passes through the atmosphere. This means less solar energy reaches the Earth’s surface. The reduction in sunlight reaching the surface is called global dimming.

Sulfur dioxide and nitrogen oxides as atmospheric pollutants

Sulfur dioxide ($$\ce{SO2}$$) and nitrogen oxides are gaseous air pollutants. When people breathe them in, they can irritate the respiratory system and worsen breathing problems. Increased amounts of these gases in the air therefore pose a direct risk to human health.

Acid rain from sulfur dioxide and nitrogen oxides

In the atmosphere, these pollutants react with water and oxygen to form acidic substances. These can fall to the ground in rain, making it more acidic. This is called acid rain.

Acid rain makes lakes and soils more acidic, harming aquatic life and plants. It can also erode stone and corrode metal structures. Unlike respiratory irritation caused by breathing the gases, this environmental damage occurs indirectly, after the gases have formed acidic substances in the atmosphere.

Carbon monoxide as an atmospheric pollutant

Carbon monoxide, $$\ce{CO}$$, is a toxic gas. It is colourless and odourless, so a person cannot easily detect it by sight or smell.

In the blood, oxygen is normally carried to body tissues by haemoglobin. Carbon monoxide binds strongly to haemoglobin, reducing the blood’s ability to transport oxygen. As a result, tissues receive less oxygen and may be seriously harmed. Severe oxygen deprivation can cause death.

Increased amounts of carbon monoxide in the air increase the risk of exposure to harmful concentrations.