As Hurricane Harvey barreled into Houston, the state shut down 50 stationary private air quality monitoring 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 cancer-causing 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 short-term 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.
Read more: Private air quality monitoring detects high levels of pollution following Harvey