Discuss measures for the control of CO pollution. 

The main source of CO pollution due to human activity is the use of internal combustion engine in the automobiles. These engines emit a mixture of CO, NO_x, hydrocarbons and particulates. The following measures may be adopted to check CO pollution:
1. By using antipollution catalysts: Automobile exhaust is treated with the antipollution catalyst before discharging into the atmosphere. It consists of two steps:
(a) In the first step, oxides of nitrogen are reduced to ammonia and nitrogen by using finely divided platinum. The quantity of NH₃ is made minimum through suitable conditions.
(b) In the second step, air or oxygen is introduced to oxidise CO and hydrocarbons into CO₂ and H₂O in the presence of finely divided Pt catalyst. In modern automobiles, catalytic exhaust reactors are used in which excess air is pumped into the exhaust gas and the mixture is passed through a catalytic converter in the exhaust system.

2. By modification of internal combustion engines: Internal combustion engines are modified to reduce the amount of pollutants formed during fuel combustion. The presence of excess air ensures complete combustion of CO and hydrocarbons to CO₂ and water.
Automobile carburettors are adjusted and cleaned regularly to the proper fuel-air ratios.

3. By using substitute fuel: Instead of gasoline, the use of CNG (Condensed natural gas) and LNG (Liquefied natural gas) have been used as these are pollution-free fuels.