**3.11 Causes of air pollution**

Air pollution can be cause by naturally as well as man-made activities.

The examples of natural sources are emissions from plants, from the biomass of the ocean, volcanic gas and the re-suspension of dust in arid areas such as deserts.

The examples of man- made source are combustion engines (both diesel and petrol), household and industry solidfuel combustion for energy production (coal, lignite, heavy oil and biomass), other industrial activities (building, mining, manufacture of cement, smelting), agriculture, with the use of entrants, and the erosion of roads by vehicles and abrasion of brakes and tyres [59].

### **3.12 Other causes are**
