Two hundred million motor vehicles are travelling the roads of the world. They are covering 2 million million miles a year and burning 70 billion litres of petrol. From their exhausts come 40 million tonnes of carbon monoxide, 4 million tonnes of nitrogen oxide, 4 million tonnes of hydrocarbons and 0.2 million tonnes of lead. These pollutants are discharged at the street level where people cannot avoid inhaling them.
To be continued