As people move from rural to urban areas, they make greater use of transport to travel to workplaces, educational institutions, markets and health care facilities as well as to keep in touch with extended families. Many urban areas of developing countries have not been able to keep up with growing demand for transport services. Cars clog inadequate road systems, public transport systems are overcrowded and overused, traffic accidents are more likely and pollution is a serious problem resulting in respiratory diseases, learning disabilities in children and cancer. Non-motorized transport is often discouraged in subtle ways, such as elimination of sidewalks and bicycle paths, as cities grow.

In developed countries, many of these problems have been solved with urban planning, traffic safety rules and better road design. Pollution has been reduced with technological innovations, such as the catalytic converter, as well as requirements for cleaner fuels. Localized pollution, such as particulate matter, sulfur oxides, nitrogen oxides, carbon monoxide and lead, has decreased but emissions of carbon dioxide, a major greenhouse gas, remain a problem.

		Urban troubles need old solutions.

Often solutions have focused on reducing pollution from vehicles rather than on changing transport systems. Urban planning can be instrumental and a greater emphasis on public transport would help in reducing both localized pollution and greenhouse gases without impeding development. As city dwellers, we can make an effort to
ride buses and subways, walk and bike routinely in our daily lives.