As firefighters continue to battle flames near the Los Alamos National Laboratory in New Mexico and its stock of nuclear materials, nearby residents are growing anxious about smoke from the blaze dispersing toxic chemicals.

While firefighters have managed to keep the now 108-square-mile conflagration away from the laboratory, scientists have been carefully monitoring the air for any traces of chemicals or radiation. The U.S. Environmental Protection Agency has aided the effort with a twin-engine plane equipped with sensors that can collect detailed air samples.

In addition to facilities used to design and test nuclear devices, the laboratory also houses thousands of barrels of radioactive waste stored above ground. Officials have maintained that the waste is safe, encased in steel drums and sitting on a concrete surface. I have 170 people who validate their measures, site manager Kevin Smith said. U.S. Sen. Tom Udall, D-N.M., said he is cognizant that people are concerned about what's in the smoke.

The lab employs about 15,000 people, covers more than 36 square miles and includes about 2,000 buildings at nearly four dozen sites.