A chemical cloud has been emanating from Conyers since Sunday, when a fire broke out at the facility of a company that makes pool and spa treatments and sprinkler system water reacted with chemicals on site. The chemical plume put residents in Rockdale County into a shelter-in-place order. Associate Professor Joseph Sadighi in the School of Chemistry and Biochemistry explained in a Q&A with 11Alive meteorologist Melissa Nord what is lingering in the air over the Conyers BioLab plant. He began with explaining the difference between chlorine and chlorine compounds. 

"Chlorine is an element that is very common in everyday life," says Sadighi. "Table salt is sodium chloride, which means it's chlorine that has picked up an electron and it's in a salt lattice that makes it very, very stable. If you run an electrical current through it, you can turn it into chlorine gas, that's a molecule made up of two chlorine atoms, and it is a gas under ordinary conditions. If we have it in a cylinder under pressure, at about eight atmospheres and room temperature, you have a liquid under the pressure of its own headspace like we do in propane gas cylinders for our grills."