When a crude-processing unit at Chevron's Richmond, Calif., refinery burst into flame in early August, sirens wailed through local neighborhoods as pillars of smoke blackened the sky over the city and surrounding hillsides.

The plant's emergency management system issued 18,000 calls to nearby residents, urging them to "shelter in place" -- closing windows, sealing cracks under doors with wet towels, turning off air conditioners -- until further notice. But hundreds of people, many from poor, predominantly black and Hispanic neighborhoods near the plant, said they received no calls. Jim McKay, a representative of the Bay Area Air Quality Management District, told a town hall meeting the next day that there had been no adverse impacts to air quality. But in the days following the fire, more than 14,000 people poured into local hospitals complaining of respiratory problems.

Chevron's 100-year-old plant has long been a source of contention in this industrial East Bay city -- and for good reason. It supports hundreds of local businesses and injects millions into the local economy, but it's also racked up dozens of air-quality violations in the last year alone, not to mention three serious fires in the last 12 years. The Richmond refinery is the state's leading source of greenhouse gas emissions and a routine violator of the Clean Air and Clean Water acts.

But the facility is hardly an anomaly. With far less publicity, two smaller Wyoming refineries went up in flames within days of the Richmond blaze. The week before, a crude unit exploded at Cheyenne's Frontier refinery. Nearby residents described feeling the heat radiating from the burning plant as they scrambled to escape the jet-black plume. No alarms sounded; no emergency phone calls were made. A few days later (just a day before the Richmond accident) a refinery operated by Sinclair, near Rawlins, burst into flame, injuring a worker. This was merely the latest of six fires at that refinery in the past three years, three of them in the last three months. There have been numerous other incidents, including the illegal discharge of oil wastes that killed more than 100 birds. (In late August, the EPA announced $3.8 million in fines against Sinclair for repeated air pollution violations at its Wyoming refineries.)

Dig into the records of any of the country's refineries and you will find a similar litany of explosions, toxic releases, violations, worker injuries -- and deaths. A recent United Steelworkers report estimated that a fire breaks out, on average, every week at a U.S. refinery. Between 2000 and 2010, at least 117 workers were killed in the nation's oil refineries and coal-processing plants, according to Bureau of Labor statistics.

Of the 45 oil refineries scattered across eight Western states, 14 are considered "large," producing more than 75,000 barrels per day. All of these large refineries are located in or near major population centers -- and many smaller facilities are smack in the middle of towns and cities. The West's most serious recent refinery disaster happened at a large refinery owned by Tesoro in Anacortes, Wash. In 2010, an explosion there killed seven workers.

In response to that and dozens of other accidents in recent years, the Occupational Safety and Health Administration and the U.S. Chemical Safety Board have issued harsh proclamations. "Bluntly speaking, your workers are dying on the job and it has to stop," said Jordan Barab, OSHA deputy assistant secretary, to a 2010 conference of refinery and mining representatives. Barab later noted, "(OSHA) inspectors have found many facilities where safety programs that look good on paper don't follow through in practice." Subsequent inspections at 50 refineries produced an average of 17 worker-safety violations totaling nearly $2 million per facility.

OSHA and the Chemical Safety Board have urged companies to more closely adhere to 'Process Safety Management' regulations, which outline how to deal with toxic materials and potential spills, fires and releases. Both groups have also advocated wider use of automated systems that monitor operations.

But for all its tough talk, OSHA has spotty oversight and little regulatory pull with refineries. In 2010, OSHA secretary David Michaels called his agency's enforcement power "weak." Maximum fines for first-time safety violations are $7,000 -- pocket change for large oil companies. (Fines for repeat violations max out at $70,000, but are rarely issued.) OSHA's 2,000 inspectors are charged with the impossible task of monitoring 8 million jobsites across the country, with no system in place to track violations by companies that operate refineries in multiple states.

The hazards workers face are shared by the public. A 2011 study by the Center for Public Integrity, for example, found that 20 percent of Americans live near enough to a refinery to be sickened or killed in the event of a release of hydrofluoric acid, a highly toxic substance used in oil refining. So as OSHA pushes for greater workplace safety, what protocols are being put in place to safeguard communities? In the case of Richmond, not many, says Greg Karras, senior scientist with the watchdog group Communities for a Better Environment. He points to the refinery's air-monitoring system, which was designed to measure average ambient conditions rather than sudden pollutant spikes emitted from events like fires: "You can't find what you can't measure for."

Meanwhile, every day is a possible emergency for the hundreds of thousands of Westerners living near refineries. Even under 'normal' operating conditions, the list of hazardous emissions pouring from refinery stacks -- not to mention 'fugitive' emissions from leaking pipes -- is long. In addition to the usual suspects, sulfur dioxide, hydrogen sulfide and large particulates, all of which contribute to asthma and heart disease, there are heavy metals and carcinogens such as benzene, toluene and hydrocyanic acid.

Though "shelter in place" may be an effective -- if politically fraught -- short-term response to accidental releases of dangerous chemicals, simply living near a refinery may prove unexpectedly hazardous over the long term. A 2008 study by researchers at the University of California, Berkeley, for example, found elevated levels of vanadium, nickel and heavy particulates derived from oil refining in Richmond's air near the Chevron refinery. But the team found an even wider array of these chemicals inside homes beside the plant. Richmond resident Malik Seneferu, who spoke at the Chevron town hall meeting, articulated the worst fears of those living in the shadow of the oil industry: "Someone earlier said if Chevron leaves, we all die. ... But if Chevron stays, we all die, too."