Univ. Of Maryland Study Suggests D.C. Heat Can Spread

Scientists at the University of Maryland are rethinking the long-held notion that urban areas get hotter and smoggier than rural areas. A new study suggests the urban heat island effect could be contagious.

Da-Lin Zhang created a 3-D model to see how weather and temperature across the D.C. area change over time.

He bulldozed Washington and replaced it with natural vegetation.

"We were surprised to see substantial reduction in temperatures in Baltimore," says Russell Dickerson, who co-authored the study with Zhang.

Zhang says the urban heat island effect, or UHI, might not be localized.

"It depends on wind direction," he says. "Warm air could affect the temperature downstream."

Dickerson and Zhang say rethinking how we plan cities, whether it's planting more trees, or replacing black, heat-trapping roofs with white ones, could reduce UHI both in the D.C. area and in developing countries across the world.