Mention any two major types of air pollutants. Add a note on their ill effects on human health.

Answer: Air pollutants are of two major types:

1. Gaseous pollutants: carbon monoxide (CO), sulphur dioxide (SO₂), oxides of nitrogen (NO_x), hydrocarbons, ozone, etc.

• CO combines with haemoglobin to form carboxyhaemoglobin, reducing the oxygen-carrying capacity of blood; it causes headache, dizziness and, in high concentration, death.
• SO₂ and NO_x irritate the eyes and respiratory tract and cause bronchitis, asthma and lung damage; they also form acid rain.

2. Particulate pollutants (suspended particulate matter): dust, smoke, soot, fly ash, pollen, asbestos fibres, lead particles, etc.

• Fine particles (PM_2.5) penetrate deep into the lungs and cause breathing problems, irritation, inflammation, asthma, bronchitis and even lung cancer and premature death.
• Lead affects the nervous system and kidneys; asbestos causes asbestosis; silica dust causes silicosis.