Aliso Canyon Gas Leak banner

Watch the Porter Ranch Community Meeting from May 19, 2016

Indoor Environmental Testing and CASPER Survey

Public Health has concluded its Community Assessment for Public Health Emergency Response (CASPER) and an Indoor Environmental Testing Protocol in the Porter Ranch area. Public Health undertook this work because, despite the end of the worst natural gas leak in US history, a majority of surveyed households reported experiencing symptoms similar to those experienced during the active gas leak even though methane and associated mercaptan levels in the air were markedly reduced.

Public Health, working closely with experts from University of California Los Angeles, the California Air Resources Board, South Coast Air Quality Management District, California Department of Public Health, Cal/EPA's Office of Environmental Health Hazard Assessment and the US EPA, tested for over 250 chemicals in indoor air and household surface dust samples. Testing was conducted in 101 Porter Ranch homes near the Aliso Canyon Storage Facility, two schools and 11 homes outside the Porter Ranch area.


As a result of these combined efforts, the following has now been determined:

  1. No contaminants were found in the indoor air of the Porter Ranch homes. The air sample testing revealed that the air in the tested homes is similar to typical indoor home environments.
  2. Testing and analysis of household surface dust in the Porter Ranch homes revealed low levels of metal contaminants consistent with those found in well drilling fluid which suggests they originated from the Aliso Canyon Natural Gas Storage facility; and,
  3. These metals do not pose long-term health risks but can cause respiratory and skin irritation and could be contributing to symptoms reported by residents.


As a result, Public Health recommends comprehensive cleaning of household surfaces, thorough ventilation of homes to flush out any residual contaminants, regular replacement of heating and air conditioning filters, and proper maintenance of air purifiers to reduce the potential for exposures that may produce symptoms. Ventilation and comprehensive cleaning guidelines can be obtained at: Link to PDF.

Public Health is directing Southern California Gas Company to offer and implement, at its own cost, the comprehensive cleaning protocol provided in the report. The directive is available here: Link to PDF.

Background Information on the Aliso Canyon Natural Gas Leak

Public Health was notified on October 28, 2015, that there was a natural gas leak that began on October 23 at the Aliso Canyon Gas Storage Facility near Porter Ranch. Since the beginning of the incident, air samples have been collected to monitor the levels of chemicals associated with the leaking gas. On November 19, Public Health issued a directive to the Southern California Gas Company (SoCalGas) to expedite efforts to stop the leak and in the interim offer free, temporary relocation to affected residents to provide relief from the odorous emissions. On December 16, Public Health directed SoCalGas to work directly with the Los Angeles Unified School District to assist in relocating affected students to alternate locations outside of the impacted area.

Since the beginning of the incident, air samples have been collected to monitor the levels of chemicals associated with the leaking gas. In January 2016, Public Health implemented the Expanded Air Monitoring Plan (EAMP) to include more community air sampling locations, to expand testing for additional chemicals, and to increase sample collection times.

On February 11, SoCalGas reported the flow of gas from Well SS-25 had been stopped, and on February 18, 2016, the California Division of Oil, Gas and Geothermal Resources (DOGGR) confirmed that the leaking well at the Aliso Canyon facility has been permanently sealed. A review of the cumulative monitoring results suggests that levels of chemicals of concern are consistent with expected background levels for the Los Angeles air basin. Outdoor air monitoring continues to be conducted and Public Health continues to address community health concerns and consult with local and State regulatory agencies. For more information on community air monitoring near Aliso Canyon please visit the California Air Resources Board and the South Coast Air Quality Management District

Public Health continues to actively monitor and assess environmental and health issues related to the natural gas leak at the Aliso Canyon Storage Facility. Some residents are continuing to report symptoms that they experienced during the leak upon returning home. Approximately 300 residents have contacted Public Health with health complaints, from mid-February to mid-April. The most common symptoms reported are headaches or migraines, nausea, nosebleeds and respiratory health issues.

Home  |
Public Health
LA County
  Careers  |   DPH Programs  |   Email: Webmaster  | Notice of Privacy Practices | 
  Website Privacy Policy  |   Language  |   Accessibility  |   Disclaimer |   Employee  |
Admin Use
Outlook E-mail
DPH Intranet (At Work)
Los Angeles County Seal: Enriching lives through effective and caring services