The toxic cocktail

Nitrogen oxides (NOx)

A group of highly reactive gases, including nitrogen dioxide (NO2), which forms a reddish brown haze

Source: Fuel combustion (electric utilities, big industrial boilers, vehicles) and wood burning

Health impact: Inflammation of the airways, lung tissue damage, reduced lung capacity, skin cancer, nerve damage

Sulphur dioxide (SO2)

Colourless gas that reacts with water vapour to form acid and interacts with other gases and particles in the air

Source: Fuel combustion

(especially high-sulphur coal), electric utilities and industrial processes

Health impact: Coughing, wheezing, shortness of breath, or a tight feeling around the chest within 10-15 minutes of exposure

Ozone (O3)

Pale blue gas with a distinctively pungent smell, which is a secondary pollutant formed when other pollutants react under sunlight

Source: Areas where scavenging takes place Health impact: Watery eyes, scratchy throat, dry cough, respiratory tract infections, chest tightness, painful deep breath, asthma, reduced lung capacity, chronic obstructive pulmonary disease, and even premature death

Volatile organic compounds

These are organic compounds such as benzene, toluene, ethylbenzene and xylene that easily become vapours or gases

Source: Incense sticks, polish and paint on walls and furniture, perfumes and deodorants and plastic items