What are the main pollutants in air?
The main pollutants in air can be categorized into several groups:
1. Particulate Matter (PM): These are tiny solid or liquid particles suspended in the air. PM can be classified into different size categories, such as PM10 (particles with a diameter of 10 micrometers or less) and PM2.5 (particles with a diameter of 2.5 micrometers or less). Common sources of PM include vehicle emissions, industrial processes, construction activities, and combustion of fossil fuels.
2. Nitrogen Oxides (NOx): These are a group of highly reactive gases, primarily nitrogen dioxide (NO2) and nitrogen monoxide (NO). NOx is released from burning fossil fuels, particularly in vehicles and power plants. It contributes to the formation of ground-level ozone and smog and can irritate the respiratory system.
3. Sulfur Oxides (SOx): These are a group of gases, primarily sulfur dioxide (SO2). They are mainly emitted from burning fossil fuels containing sulfur, such as coal and oil. SOx can lead to respiratory issues, acid rain, and contribute to the formation of particulate matter.
4. Volatile Organic Compounds (VOCs): VOCs are a wide range of carbon-based chemicals that easily turn into vapors or gases at room temperature. They are released from various sources such as vehicle emissions, industrial processes, solvents, paints, and household products. VOCs can contribute to the formation of ground-level ozone and can have both short-term and long-term health effects.
5. Carbon Monoxide (CO): This is a colorless and odorless gas produced from incomplete combustion of fossil fuels, particularly in vehicles and poorly ventilated appliances. High levels of CO can be toxic and reduce the ability of blood to carry oxygen to the body's organs and tissues.
6. Ozone (O3): While ozone in the upper atmosphere (stratospheric ozone) is beneficial as it protects us from the sun's harmful ultraviolet (UV) radiation, ground-level ozone can be harmful. It forms through complex chemical reactions involving sunlight, nitrogen oxides, and volatile organic compounds. Ground-level ozone can cause respiratory problems, eye irritation, and can damage crops and vegetation.
These are some of the major pollutants in the air. However, there are other pollutants as well, including hazardous air pollutants (HAPs) like lead, mercury, and other heavy metals, as well as persistent organic pollutants (POPs) like dioxins and furans, which are highly toxic and can have long-lasting effects on human health and the environment.