Why is pollution considered as a major problem in urban areas?

Concentrated energy use leads to greater air pollution with significant impact on human health. Automobile exhaust produces elevated lead levels in urban air. Large volumes of uncollected waste create multiple health hazards. Urban development can magnify the risk of environmental hazards such as flash flooding.

seismic wave -

an elastic wave in the earth produced by an earthquake or other means.

explanation:

answerhydrogenous sediment;