When I moved less than three miles away from the Valero oil refinery in Benicia just over two years ago, I wondered if it was safe to live so close to a compound designed solely to process toxic materials. From time to time, I catch a whiff of rotten eggs, indicating the presence of sulfur in the breeze, but I never had cause to second-guess my decision until a few weeks ago.

On May 9, the Bay Area Air Quality Management District, a government agency that regulates air pollution in the Bay Area, issued the refinery six violations; four for excess visible emissions and two public nuisance violations, for a flaring incident that occurred the week prior, according to a BAAQMD press release.

On May 5 at approximately 6:45 a.m., Valero lost power due to a PG&E outage, which caused thick black smoke to flare from refinery stacks, officials from Valero, the U.S. Environmental Protection Agency and the city of Benicia confirmed during an emergency press conference the morning of the incident.

At a city council meeting on Tuesday, PG&E claimed it was conducting an investigation into the incident. The smoke contained hydrogen sulfide and sulphur dioxide gases, which are byproducts of the crude oil and refinery process and can present a wide variety of health detriments, Steve Calanog, U.S. EPA Federal On-Scene Coordinator, confirmed.

On Friday morning around 6:45 a.m., refinery employees alerted city officials about the incident. At 7:30 a.m. the Benicia Industrial Park, which houses 450 businesses and 6,500 employees,according to the City of Benicia Office of Economic Development, was evacuated because it was directly in the line of smoke. CalTrans closed the 680 on-ramps leading to the park and the city issued a precautionary shelter-in-place notice for Matthew Turner and Robert Semple Elementary Schools, the closest schools to the refinery.

The shelter in place didn’t apply to surrounding residential neighborhoods, but concerned residents were advised to bring pets indoors and stay inside with the windows closed, according to Jim Lydon, Benicia Fire Chief and Acting Assistant City Manager.

My house is sandwiched right between Robert Semple Elementary and Valero and I blissfully slept through the entire incident, completely unaware of the poisonous air outside, with windows wide open. The air monitoring, which was conducted by EPA personnel, Benicia Fire Department, Bay Area Air Quality Management District, California Air Resources Board, Solano County Department of Health and the Solano County Office of Emergency Services, revealed peak readings of up to 10 times the normal levels of the aforementioned gases, Calanog confirmed.

The air showed signs of non-detect for the substances at 2 p.m. which prompted a lift of the evacuation and shelter-in-place warnings, confirmed Michele Huitric, EPA spokesperson.

The evening before the incident, the weather was hot so all of the windows in my house were open all night, since I have no air conditioning and live in an in-law unit on top of a house.

During situations like this, the city of Benicia deploys seven emergency sirens that are placed throughout the community to notify residents, Lydon confirmed. It also broadcasts on the city’s local TV station, posts on the city’s website and various social media outlets, and uses AlertBenicia, an emergency notification system that utilizes 911 contact data and contacts people through cell phone numbers and email addresses of those who manually registered on the site.

However, I didn’t hear about the incident that happened practically in my backyard from any of these alert methods; I found out thanks to a KRON4 news article that popped up oh my Twitter feed later that day. My ignorance about the incident was alarming and immediately made me question the competency of the city’s emergency alert system.

After checking the city’s Facebook page, which provided live updates throughout the day, I discovered that other residents voiced similar concerns about not receiving an official alert from the city.

Lydon told the Pioneer that the city received comments from various people who both did and didn’t hear the sirens and pointed out that these reports were likely based on a variety of factors, including whether windows were closed or what activities people were doing when the sirens were deployed. Lydon said the city intends to analyze the siren and system’s scope of coverage.

This was the first shelter-in-place order issued in the city since April 2013, Lydon told the Pioneer. A 2010 incident activated the city’s emergency alert sirens; however, a shelter-in-place warning wasn’t issued at that time and the city has no record of a shelter-in-place order before 2010. Even though this doesn’t happen often, it was still a wake-up call for me that there are risks associated with living next door to an oil refinery.

In comparison to other oil refineries, Benicia’s Valero refinery is one of the safest in the state. The Benicia refinery is one of two in California to earn the Voluntary Protection Program “Star Site” designation for health and safety programs that successfully control occupational hazards, according to Valero public affairs manager Sue Fisher Jones. The Benicia refinery has passed two recertification audits since earning the title in 2006.

According to an Environmental Impact Report supplied by the city of Benicia, the Valero refinery currently produces ten percent of the gasoline used in California, and 25 percent of the gasoline used in the Bay Area. The 900-acre refinery provides approximately 400 jobs, both to Benicia residents and nonresidents, according to Valero, and is the largest employer in the city.

Don Cuffel, director of health, safety and environmental affairs at Valero, explained at the emergency press conference that flaring is an indication that the system was working properly. Flares are an industrial safety device that burns hydrocarbons that can’t be safely stored in a controlled manner during power outages and other situations, according to Cuffel. If the equipment didn’t flare off the gases that were trapped and built up mid-operation, the equipment would combust.

“Flaring is a necessary part of a safety system for a refinery to have,” he said. “Without the flare you can’t protect your equipment or your community. So as much as people may not want to see it, I would say ‘look at the flare when it’s going off, it’s your friend because it’s doing what it’s exactly supposed to do.’”

When it comes to refinery operations, it appears that the equipment made to minimize larger risks can be dangerous itself. While I never got sick from the incident, Benicia Vice Mayor Steve Young confirmed that at a city council meeting on Tuesday, several citizens reported health issues.

I think that the city’s operating under a sense of false security because these things don’t happen very often. But they do happen and the city of Benicia will need to dust the cobwebs off their alert system to ensure that we’re all prepared when it does.