BIRMINGHAM, Ala. (AP) - More than 50 people have been sent to hospitals around Birmingham, Alabama, following a chemical spill at a water treatment plant.

  

Authorities tell news outlets that irritating gas caused by a mixture of ferric sulfate and sodium hypochlorite was causing breathing problems for about a dozen workers.

  

Roughly 40 more people were sent to hospitals as a precaution. Authorities say exposure to the chemicals can cause respiratory problems, nausea and headaches.

  

The spill occurred Wednesday morning at a Birmingham Water Works plant along a heavily traveled suburban highway.

  

Authorities asked people living and working in the area to stay inside to avoid the fumes. Officials with the water system say the water is still safe to use.