AQ Monitoring Results:
Crockett: Nickel at John Swett
This page last reviewed September 27, 2010
Nickel is an odorless, silvery, dark-gray metal. It is highly ductile, and has good thermal and electrical conductivity.
Nickel also exists in many compounds. California has determined under Assembly Bill 1807 and Proposition 65 that nickel and certain nickel compounds are cancer-causing compounds. Inhalation exposure to nickel refinery dust and some nickel compounds has caused nasal and lung cancer in refinery workers. Long-term exposure to nickel may cause respiratory tract irritation, immune alterations such as dermatitis ("nickel itch") and asthma. Intense exposure to nickel and nickel compound fumes may cause irritation of the respiratory tract, skin, and eyes.
Fuel combustion (residential oil, distillate oil, coke and coal) is responsible for the majority of the nickel emissions in California. The primary industrial sources that have reported nickel emissions are crude oil and gas extraction, electrical services, and national security installations. Nickel has also been detected in motor vehicle exhaust. For indoor air, tobacco smoking is the major source of nickel emissions. A single cigarette contains 1-3 micrograms (µg) of nickel. Natural sources of nickel in the atmosphere include soil, sea spray, volcanoes, forest fires, and vegetation. Wind erosion and volcanic activity contribute approximately 40% to 50% of the atmospheric nickel from natural sources.
The Air Resources Board (ARB) adopted an airborne toxic control measure in 1993 for non-ferrous metal melting operations. This control measure is expected to reduce emissions of nickel by 99%. From year 1990 to year 2000, the average nickel concentration in California has reduced approximately by 30%.
Ambient Monitoring Results
Ambient levels of nickel (including the metal nickel and the nickel in compounds) are routinely monitored at approximately twenty sites in the California air toxics monitoring network. The statewide average concentration of total nickel during 1998-2000 was 3.7 ng/m3 (nanograms per cubic meter), based on values ranging from 0.7 ng/m3 to 60 ng/m3.
The current routine monitor closest to Crockett is in Fremont. Relative to the statewide average, the Fremont region was 27% lower, with an average concentration of 2.7 ng/m3 for the same time period.
The ambient monitoring results at John Swett are provided here:
- A graph comparing the monthly summaries of nickel at the community with historical statewide and regional levels
- A table of summary statistics
- Raw data in Excel format
Cancer risk is the number of excess cancer cases among a million people if the people are exposed to levels of a toxic air pollutant over 70 years. Nickel is equivalent to less than 1% of the potential cancer risk of the nine measured compounds and the estimated diesel particulate matter.