It becomes more common that citizens of developing countries are able to afford their own first vehicle. The principal problems this causes are pollution and traffic congestion, and the most viable solution is development of the local public transport infrastructure.
The primary issue developing countries face when their citizens start to buy cars is increased pollution. This occurs as a result of the fact that people from developing countries tend to buy cheap cars with not very fuel effective engines and without proper gas filters, and due to a poor quality of the most affordable gasoline. The greater number of vehicles on the road is also responsible for a rise in traffic jams. This is because of underdeveloped road infrastructure, that is unable to process such a quantity of cars, and lack of experience of new drivers and policemen, who faced a new challenge of unusually large number of cars on streets. For example, in India, city roads may look like a mess of chaotically moving cars.
A solution to these problems is to increase accessibility and quality of public transport. This would solve the problems by reducing the number of people using private cars. For example, Moscow has one of the biggest metro systems in the world, which makes possible traveling to any part of the city faster than using a car, so many choose it instead of a personal vehicle.
In conclusion, the rise in emission of toxic and greenhouse gases and the road traffic related problems in developing countries are caused by an increasing number of new car owners, but this may be solved by enhancing means of public transportation.