The haze that seized metro Atlanta by the throat the past few days is expected to continue at least through Tuesday.

And it's not just here. The National Oceanic and Atmospheric Administration is tracking the same bad air mass across the Southeast, from Louisiana to Georgia, said Michael Chang, an atmospheric scientist at Georgia Tech.

"They've characterized it as 'of unknown origin,'" Chang said. "It's not attributable to any fires or explosions or volcanic eruptions, or anything that typically you might associate with it."

Unusually, both ground-level ozone and fine particles, or soot, have been high. Ozone is the more common cause of smog alerts. Both pollutants are harmful to public health, particularly children and people with heart and lung diseases. Starting last July 15, ozone levels in metro Atlanta have violated the federal limit on six days. Particle pollution has violated the standard on three days. Tuesday is expected to be another code orange day.

Bill Murphey, chief meteorologist for the state Environmental Protection Division, said the most likely source of the bad air is us.

Hot, stagnant air is trapping emissions from the region's traffic, factories and power plants, forming a lid on the chemical stew. Tuesday is expected to be the fifth consecutive day of 90-plus temperatures.

Murphey sees a break in the pattern starting late in the day, when isolated thunderstorms are expected.