Table 1.
Common sources of major air pollutants
| Pollutant | Ambient | Household | |
|---|---|---|---|
| Primary pollutants | |||
| CO | Incomplete combustion of carbon-containing fuels, vehicular exhaust, and photochemical reactions in the atmosphere | Gas stoves and tobacco smoke | |
| SO2 | Industrial activities that process sulfur-containing fuels, and motor vehicles emissions | Combustion of coal/oil | |
| NO2 | Power plants and motor vehicles emissions | Gas and kerosene heaters, and tobacco smoke | |
| PAHs | Incomplete combustion of organic materials (e.g., coal, oil, petrol, and wood) | Wood stoves, barbecues, and tobacco smoke | |
| VOCs | Fossil fuels and motor vehicles emissions | Paints, disinfectant, air-fresheners, and photocopy machines | |
| Secondary pollutants | |||
| PM | Directly emission or transformation of gaseous emissions (e.g., SO2, NO2, VOCs) by motor vehicle combustion of solid/fossil fuels, and forest fires | Gas/wood stoves, and gas space heaters | |
| O3 | The reaction of NO2 and VOCs in the presence of sunlight | None | |
CO, carbon monoxide; NO2, nitrogen dioxide; O3, ozone; PAHs, polycyclic aromatic hydrocarbons; PM, particulate matter; SO2, sulfur dioxide; VOCs, volatile organic compounds.