With billions of dollars in planned commercial developmentprojects and billions more in federal aid hanging in the balance,it's a race that LA hopes to lose. With only a few weeks left inthe nation's smoggiest season of the year, 100-degree heat and highhumidity in Houston over the Labor Day weekend pushed that city'sair-quality levels down to the federal government's "unhealthy"level. But in Los Angeles, 80-degree weather and mild breezes madebreathing in the LA Basin much easier.

So far this year, Houston has had 36 days when its air-qualitylevels didn't meet national health limits for ozone. LA has had34.

Though the two cities have recently been poking fun at eachother over the dirty-air race, it's really no laughing matter. Inaddition to endangering public health, cities that don't meetfederal clean air standards risk losing billions of dollars ingovernment aid. State and federal authorities can even ban new realestate projects in a city if they feel additional constructionwould worsen air quality.