In order for the public to be informed about methane concentrations that may be related to the natural gas plume and specifically its potential distribution into the Porter Ranch community, the California Air Resources Board (CARB) and the SCAQMD are combining their continuous methane monitoring efforts to display the near-real-time methane monitoring data. Recent monitoring values are shown in the time series below.
Locations of the continuous methane monitors are shown in the map below:
Methane is measured in parts per million, or ppm. Normal background is approximately 2 ppm. Results greater than 3 ppm suggest some additional sources of methane, and results greater than 10 ppm suggest a considerable additional amount of methane is present.
Data taken directly from the SCAQMD automated monitoring system have not been validated extensively and, therefore, are subject to change. The results from these monitors alone cannot be used to infer health effects, but they do provide a general sense of how much natural gas is in the community at a given time.
Previous SCAQMD continuous methane measurements are located here and at the CARB website here. The graph below shows the sharp decrease in ambient methane levels after the gas leak from well SS-25 was stopped on February 12, 2016.