Measuring the exposure
Private air monitors detect high levels of pollution following Harvey
AS Hurricane Harvey barreled into Houston, the state shut down 50 stationary air quality monitors that track pollution levels to protect the sensitive devices from the high winds and torrential rains that swamped the region.
The timing, while perhaps unavoidable, couldn’t have been worse. Over the week — longer in some neighborhoods — that the air monitors were out of commission, record floods triggered spills from refineries, chemical plants, pipelines and storage tanks that released volatile chemicals into the air.
The extent of exposure to these pollutants, some known to cause cancer, may never be known, but since the skies cleared and floods receded, a small corps of private air monitors have spread out into the neighborhoods near the spills and found that emissions likely reached dangerous levels — in some cases more dangerous than environmental regulators initially acknowledged.
On Aug. 27, for example, Valero Energy said a collapsed roof at its East Houston refinery led to a small release of cancercausing chemical benzene, a particularly dangerous and volatile component of oil and gasoline that evaporates quickly. Eight days later, air monitoring in the adjacent Manchester neighborhood by the San Francisco company Entanglement Technologies detected a plume of benzene with readings nearly double the state’s allowable level for shortterm exposure.
“We certainly didn’t expect to see concentrations that are this high,” said Tony Miller, Entanglement’s CEO. “Extremely high measurements could’ve been here shortly after the accident.”
Entanglement’s work was part of an effort by the Environmental Defense Fund, a national advocacy group, and the nonprofit Air Alliance Houston to help the city of Houston assess environmental damage from Harvey, protect public health and hold companies accountable for their pollution. Refineries, petrochemical plants and other industrial operations spewed some 2.6 million pounds of pollutants into the air during Harvey-related shutdowns and accidents in the Houston area, according to self-reported emissions to the Texas Commission on Environmental Quality.
That’s equal to about half of the emissions reported for all of last year for emergency shutdowns, maintenance and accidents.
“We have one of the largest air monitoring networks of any area in the United States, but we still have areas where they can’t monitor well,” said Loren Raun, chief environmental science officer for the Houston Health Department. “We were scrambling to understand everything Harvey could have created in terms of environmental pollution.”
Air monitoring first started in Houston and across the nation in the 1970s under the federal Clean Air Act, expanding from city centers into neighborhoods and industrial areas. When Hurricane Harvey threatened, the stationary monitors were disassembled and put into temporary storage, then reinstalled and recalibrated after the storm passed. Most were back online by Sept. 2, but the Milby Park monitor closest to the Manchester neighborhood didn’t restart until Sept. 8.
Following the series of spills, the Environmental Defense Fund, which has actively pursued air emissions issues in the Houston area for years, hired Entanglement to do air quality monitoring, along with two other mobile monitoring units that EDF has available through a partnership with Google. They traveled through the Houston area, detecting elevated benzene levels in areas like Baytown, Pasadena and Port Arthur.
“The bottom line is these mobile units see things the stationary monitors can’t pick up,” said Elena Craft, an Environmental Defense Fund senior health scientist in Texas. “And that’s incredibly concerning.”
The findings in the Manchester neighborhood provide an example. Located in the shadow of the Valero refinery, some homes in the largely Hispanic, lower-to-middleclass neighborhood sit right next to the refinery, which can churn through more than 200,000 barrels of crude oil a day to produce a variety of fuels and petroleum products. A 2016 Union of Concerned Scientists report found that the cancer risk in Manchester is 22 percent higher than for all of Houston, and about 30 percent higher than in some more affluent West Houston neighborhoods.
Two days after Harvey struck the Texas coast, the weight of rainwaters buckled and partially collapsed the roof of a storage tank at Valero’s refinery, while damaging the roof drain of another tank. The exposure of the petroleum to the air led to the release of benzene.
Valero said it quickly contained the oil after it leaked from the roof drain, spraying foam materials to prevent benzene and other volatile components from evaporating. Within 24 hours of the accident, when details often remain murky, Valero estimated the accident released just 6.7 pounds of benzene, as well more than 3,350 pounds of unspecified volatile organic compounds.
The U.S. Coast Guard inspected the cleanup, and Valero said it was working with the Texas Commission on Environmental Quality and EPA “on monitoring for any potential emissions from the oil.”
For several days after Harvey, both agencies frequently repeated that throughout the region “monitors are showing that air quality at this time is not concerning, and residents should not be concerned about air quality issues related to the effects of the storm.”
The Environmental Defense Fund, however, was concerned. Miller, the Entanglement CEO, and his chief science officer, Mike Armen, drove more than halfway across the country in three days, settling in the Manchester neighborhood on Sept. 4.
The EPA said it had monitored the area but found no readings above emergency screening levels. Entanglement, however, came up with much more alarming findings, detecting benzene concentrations of 324 parts per billion, nearly double the state’s allowable amount of 180 parts per billion for short-term exposure. Separate monitoring by the city confirmed those readings.
“It’s been quite some time, and we’ve still seen high concentrations,” Miller said.
Ten days later, on Thursday, the EPA acknowledged that Valero “significantly underestimated” the size of the benzene leak and would file a new report showing a “substantial increase” in emissions. The agency, however, declined to release the revised data until the report is complete. Meanwhile, the EPA is demanding Valero turn over records and maintenance history related to the tank failures at the refinery, including detailed calculations of emissions and efforts taken to prevent and mitigate them before and after the incident.
Valero, which contends there was never a serious health risk to the community, acknowledged it will report elevated emissions from the incident, but added that it believes that the highest concentrations of benzene may have come from other refineries and chemical plants in the area. Some chemicals detected in the air with benzene plumes aren’t present in the failed tank.
Edna Acosta lives across the street from the refinery. She grew up in the neighborhood and is accustomed to the smells of petroleum. She said the odors got much worse after Harvey, but she didn’t know what she could do.
“You get too comfortable with it. That doesn’t mean you’re satisfied,” Acosta said. “I do get concerned because I have my kids. Your front yard is literally the refinery.” jordan.blum@chron.com twitter.com/jdblum23