Naturally-Occurring Asbestos - Air Monitoring

This page last reviewed July 2, 2008

Asbestos Air Monitoring - ORHS Estimated Risk Comparison

Summary of ARB Asbestos Ambient Monitoring from 1998 to 2003

The overall average concentration from this monitoring effort was 0.0008 s/cc. To put these levels in perspective to other asbestos monitoring studies the ARB has conducted, please see the table below.

It is important to understand that these results are individual measurements at specific locations at the high school and do not represent what the average or typical asbestos exposures may be in any broad area (e.g. El Dorado County). Additionally, the estimated potential cancer risks provided assume that a population would be continuously breathing those levels over a lifetime (about 70 years). This should not be interpreted to mean that it is necessary to be exposed to asbestos for 70 years in order to contract asbestos-related cancer. Rather, the potential cancer risk is a high-end estimate of the number of cases in a population of a million people exposed over a lifetime. Since we do not have approved methodologies or health values for estimating potential cancer risks from the short-term exposures measured at the high school, the use of lifetime potential risks estimates shown in table below provides an easy-to-understand basis when comparing results from various monitoring studies.

Monitoring Location

Sampling Dates

Number of Samples Collected

Average Concentration (s/cc)

Potential Cancer Risk1,2 (chances/million)

El Dorado County

Various months during 1998, 1999, 2000, and 2001

387

0.0057

36

El Dorado County - Near Potential Source

October 1998

110

0.0136

85

Placer and Nevada Counties

July 1998

37

0.0032

20

Monterey County

June 2001

98

0.0028

17

Santa Clara County

July 2001 and September 2001

98

0.0136

85

Oak Ridge High School

June 2003 and July 2003

224

0.0008

5

  1. Risk estimates are consistent with the Cal/EPA Office of Environmental Health Hazard Air Toxics Hot Spots Program Guidance Manual for Preparation of Health Risk Assessments (August 2003) and ARB Recommended Interim Risk Management Policy for Inhalation-Based Residential Cancer Risk. The potential cancer risks are for comparison purposes only. All results have been rounded.
  2. The result are for mesothelioma and have been rounded.
 

Air Toxics Program

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