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Urban pavements pollute air by interfering with 'dirt clearing' breezes

June 8, 2011 - Washington

A new study has suggested that widespread urban development alters weather patterns in a way that can make it easier for pollutants to accumulate during warm summer weather instead of being blown out to sea.

The findings could have implications for the air quality of fast-growing coastal cities and other mid-latitude regions overseas.

The international study, led by the National Center for Atmospheric Research (NCAR), showed that proliferation of strip malls, subdivisions and other paved areas might interfere with breezes needed to clear away smog and other pollution.

To come to the conclusion, the researchers combined extensive atmospheric measurements with computer simulations to examine the impact of pavement on breezes in Houston.

They found that, because pavement soaks up heat and keeps land areas relatively warm overnight, the contrast between land and sea temperatures is reduced during the summer.

This in turn causes a reduction in nighttime winds that would otherwise blow pollutants out to sea.

In addition, built structures interfere with local winds and contribute to relatively stagnant afternoon conditions.

"The developed area of Houston has a major impact on local air pollution," said NCAR scientist Fei Chen, lead author of the new study.

"If the city continues to expand, it's going to make the winds even weaker in the summertime, and that will make air pollution much worse," he said.

The study will be published this month in the Journal of Geophysical Research.


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