EPA testing air after twister in toxic Okla. town

Miles Tolbert, the Oklahoma secretary of the environment, said he did not think there was an immediate public health hazard to the town's 800 residents, but said more testing is needed.

Long-term exposure to lead dust poses a health risk, particularly to young children.

On Saturday, a tornado with the second-strongest rating killed six people, destroyed a 20-block area and blew dust off mountains of mining waste, or chat piles.

"You can look at the chat piles and see that a lot of the material has blown off," said John Sparkman, head of the Picher housing authority. "We went up on a chat pile an hour and a half after the tornado hit, and you could see dust blowing fine material all over the place from that vantage point."

In all, 22 people were killed in the tornado outbreak in Oklahoma, Missouri and Georgia.

Meanwhile, law enforcement officers and the Oklahoma National Guard patrolled the Picher overnight into Monday to prevent looting, said Michelann Ooten, spokeswoman for the Oklahoma Department of Emergency Management.

National Weather Service assessment teams determined the twister that hit Picher had an EF-4 rating, the second highest rating, and was 1 mile wide at its widest point, meteorologist Mike Teague said Monday.

The tornado's winds were estimated at 165 to 175 mph, and the damage track stretched 74 miles -29 in Oklahoma and another 45 in Missouri, where 15 people were killed.

"These storms are fairly rare to be that strong. The devastation was nearly complete in a few areas," Teague said. "Albeit isolated, there were some sections of neighborhoods where houses were just completely taken off the foundation. Gone."