Pacific Gas & Electric Company released an alert of decreased oxygen levels for a containment unit at the Diablo Canyon Power Plant in San Luis Obispo County on July 28.

The alert began at 12:06 p.m., but the company said both units were operating at full power and employees and the public were not at risk. Plant personnel would need to use additional breathing equipment when entering the area in the event of an emergency, it said.

The alert will be lifted when the oxygen level, which is now at 18.5 percent, rises back above 19 percent. PG&E said it did not know the cause of the decline at the time of the alert.

A joint information center was opened at 1133 Kansas Ave. in San Luis Obispo, operated by PG&E and the county Office of Emergency Services. The public can also obtain information by calling the company’s toll-free service line at 1-800-PGE-5000, or at http://www.diablocanyonpge.com.

• Contact Marissa Nall at mnall@pacbiztimes.com.