RICHMOND (CBS SF) – Hazardous materials crews were in route to the Richmond Chevron refinery Monday after reports of flaring at the facility.

Officials say no shelter in place has been issued but Contra Costa County had sent out a public health advisory for Richmond, North Richmond and San Pablo..

People with respiratory conditions are encouraged to remain inside until the smoke subsides, especially if they are downwind.

Contra Costa County Public health workers are monitoring conditions in the field around the refinery.

The flaring was due to depressurizing a processing unit.

Chevron officials say the flaring has since ended.

Last December, there was significant flaring visible across the region at the refinery. Despite assurances from Chevron they were routine, later, officials said they were, in fact, an emergency reaction to something that went wrong at the plant.Chevron Refinery Flare

Large flames emanated from Chevron’s refinery in Richmond on Thursday night. (CBS)