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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.

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Public Health has made reasonable efforts to provide accurate translation. However, no computerized translation is perfect and is not intended to replace traditional translation methods. If questions arise concerning the accuracy of the information, please refer to the English edition of the website, which is the official version.
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