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
Health impact: Persistent dry cough, irritable and watery eyes, itchy skin, rashes, fatigue, high blood pressure, artery blockage, lung damage