Contra Costa Health Investigating Oct. 6 Coke Dust Release at Martinez Refining Company

A picture of Martinez Refining Company in the distance with residences in the foreground.
Contra Costa’s Health Department issued a warning to the community after Martinez Refining Company (MRC, pictured) accidentally released petcoke dust at 10:31 am during maintenance. In order to prevent disruption of Alhambra’s High School homecoming parade and other Friday night community events, MRC will use a different process to finish the maintenance work that triggered the release.  | Anda Chu / Bay Area News Group.

For Release: Friday, October 6, 2023
Contact: CCH Media Line, 925-608-5463 or

Contra Costa Health (CCH) deployed a hazardous materials team to investigate a reported release of petroleum coke dust from Martinez Refining Company (MRC) about 11 a.m. Friday, Oct. 6.

The release ended soon after it was reported by MRC to Contra Costa County’s Community Warning System. CCH has not found evidence of any immediate risk to public health in surrounding communities.

MRC reported that the release began at 10:31 a.m. while workers were conducting maintenance, which was stopped due to the release.

CCH is aware of the Alhambra High School homecoming parade set for Friday evening. MRC confirmed there will not be additional maintenance on Friday, and they will use a different process to complete the work.  [Emph. added by BenIndy.]

Following an assessment by our health officer, CCH believes the homecoming parade and other community events can proceed as planned.

CCH has asked the facility to provide a 72-hour report regarding the cause of the release, which will be posted at