Table 1.
Main pollutants and sources of pollution.
| Pollutant | Origin |
|---|---|
| Primary pollutants | |
| Carbon monoxide (CO) | Industrial combustion, vehicles (fossil fuels and diesel) |
| Sulphur dioxide (SO2) | Diesel and fossil fuels Natural activity: volcanic eruptions |
| Secondary pollutants | |
| Nitrogen dioxide (NO2) | Industrial combustion, vehicles (fossil fuels and diesel), thermal power plants |
| Ozone (O3) | Photochemical reaction of NO2 and volatile organic components |
| Primary and secondary pollutants | |
| Particulate matter (PM) | Power plants, vehicles (diesel fuels) |