Metals caused Porter Ranch health problems

A NEW study in the Porter Ranch area of California, US, near the site of the Aliso Canyon gas well blowout, has found that residents’ health problems were likely caused by metals present, rather than the leak itself.

The Aliso Canyon gas well in southern California, US, owned by Southern California Gas Co (SoCal) began leaking methane at a rate of around 30,000 kg/h in October 2015, after a pipe ruptured. Despite several attempts at sealing the well and drilling relief wells, it wasn’t until February that SoCal announced that the well had been sealed. Researchers from the University of California, Irvine (UCI) and the National Oceanic & Atmospheric Administration (NOAA) calculated that more than 100,000 t of methane was released from the well.

More than 2,000 households in the Porter Ranch area were evacuated in the surrounding regions after residents reported health problems such as nausea, headaches or migraines, breathing difficulties, rashes and nosebleeds. These were originally blamed on mercaptan, an odorant added to natural gas to allow it to be easily detected. However, mercaptan is not known to cause nosebleeds or rashes, and evacuated residents who have returned to their homes following the sealing of the well have continued to report the health problems.

Around 300 residents reported problems to the Los Angeles County Department of Public Health, which as a result, has been carrying out a Community Assessment for Public Health Emergency Response (CASPER) and an Indoor Environmental Testing Protocol in the area. These assessments have now concluded.

Public Health found no evidence of air contamination of methane or mercaptan inside any of the homes it tested. However, surface dust samples were found to contain low levels of metal contaminants “consistent with those found in well drilling fluid”, suggesting that they originated at the Aliso Canyon well. The department says that while the metals pose no long-term health risks, they can cause respiratory and skin irritation and could be causing the symptoms reported by residents. The metals present include barium, manganese, vanadium, aluminium, and iron.

The assessments took in 101 homes with the area, 11 homes outside of the area and two schools. The department worked with various experts including at the University of California Los Angeles (UCLA), the California Department of Public Health, and the Environmental Protection Agency.

Public Health recommends that all homes are thoroughly cleaned and ventilated. It has directed SoCal to immediately offer “comprehensive cleaning” to all residents with Porter Ranch, who participated in the relocation programme or who live within five miles of the blown-out well at its own expense.

SoCal said that the results proved that there was no risk to public health and urged residents to return home so that the community could “be whole again”. It did not comment specifically on the directive.

“We continue to work to support the transition back to normalcy. Over the past several months, our dedicated employees, many of whom live in Porter Ranch, have served more than 30,000 resident visits at our Community Resource Center, provided temporary housing for 8,000 families, processed more than 41,000 reimbursements totalling US$76m, installed 38,000 air filtration systems, and cleaned, public parks, playgrounds, and schools,” said SoCal in a statement. “We continue to work quickly to process reimbursements, and we will deliver on our promise to mitigate the greenhouse gas emissions from the leak.”