There are natural sources of hydrocarbons. Methane, is produced when dead plant material decays in the absence of air. Although only 15 percent of the hydrocarbons in the air come from our activities, they affect human health because they are concentrated in city air.
Hydrocarbons by themselves cause little damage. In sunlight, they react with the oxygen and oxides of nitrogen in the air. As a result these photochemical reactions *reactions which are brought about by light), irritating and toxic compounds are formed. The irritating smog on Los Angeles in the USA is mostly of photochemical origin. It is known as photo chemical smog.
The hydrocarbons emitted by petrol engines can be reduced by increasing the oxygen supply so as to burn the petrol completely. There is a snag. The problem is this that in increase of oxygen there will be a decrease in hydrocarbons and carbon monoxide in exhaust gases but there will be an increase in oxides of nitrogen in exhaust gas.
Chemists are doing research on the problem. The solution may be to run engines at a lower temperature (in order to reduce the combination of oxygen and nitrogen) and employ a catalyst t (to ensure the complete combustion of hydrocarbons at the lower temperature)
Hydrocarbons by themselves cause little damage. In sunlight, they react with the oxygen and oxides of nitrogen in the air. As a result these photochemical reactions *reactions which are brought about by light), irritating and toxic compounds are formed. The irritating smog on Los Angeles in the USA is mostly of photochemical origin. It is known as photo chemical smog.
The hydrocarbons emitted by petrol engines can be reduced by increasing the oxygen supply so as to burn the petrol completely. There is a snag. The problem is this that in increase of oxygen there will be a decrease in hydrocarbons and carbon monoxide in exhaust gases but there will be an increase in oxides of nitrogen in exhaust gas.
Chemists are doing research on the problem. The solution may be to run engines at a lower temperature (in order to reduce the combination of oxygen and nitrogen) and employ a catalyst t (to ensure the complete combustion of hydrocarbons at the lower temperature)
