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Home Air Criteria Pollutants

PM10 Annual Average Concentration

Status and Trend

Interpretation and Commentary

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Status: Unknown
Trend: Unknown
Confidence: N/A

  • Relevance - This indicator measures the annual average concentration of particulate matter less than or equal to 10 microns in size (PM10). In high concentrations this pollutant can lodge in the lungs and cause or aggravate the effects of asthma, lung diseases, and heart disease. Federal and state standards have been adopted to protect the public from this pollutant.
  • Adopted Standards - TRPA: TRPA does not have an adopted Threshold Standard for Particulate Matter. However, it does have Numerical Standards for wood smoke and suspended soil particles to protect regional visibility; “Reduce suspended soil particles by 30% of the 1981 base values through technology, management practices, and educational programs. Reduce wood smoke emissions by 15% of the 1981 base values through technology.” California: Do not exceed the 20 mg/m3PM10 annual average concentration; Federal: Do not exceed the 50 mg/m3 annual average PM10 concentration measured three years running.
  • Indicator - Annual average PM10 concentrations measured at any permanent monitoring station within a calendar year (mg/m3).
  • Status – The current status is designated as “unknown” because the most recently reported annual average PM10 concentration at the Sandy Way site was from 2006 (CARB 2011a), which is not representative of current conditions. The annual average PM10 concentration measured in 2006 was 17.1 µg/m3, which is 86% of the CA standard of 20 µg/m3. According to the available data record, the Tahoe Region was in attainment with this standard every year from 1998 through 2006. Available data related to the federal 3-year running average ranged from a high of 24 µg/m3 in 1996, continually decreasing to 19 µg/m3 in 2003 (data beyond 2003 were not available).
  • TrendTrends were calculated from available data using a Thiel regression model.
    • Long Term Trends - There was a long-term trend between 1994 and 2006 at the South Lake Tahoe site of decreasing annual average PM10 concentration of -0.7µg/m3.-yr. This change is equal to -3.5% per year of the most conservative California standard of 20 µg/m3,and would indicate a “rapid improvement” trend designation. However, because current data were not available, a trend determination of “unknown” was assigned.
    • 5 Year Trend - No PM10 monitoring data were available for the Basin after 2006 to determine a 5-year trend.

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  • Confidence
    • Status - The data were collected continuously between 1989 and 2006 using federal reference methods (EPA 2011b), and the data was subject to extensive quality assurance requirements. However, no data has been collected in the past 5 years to determine the current status of annual average PM10 concentration. Thus, confidence in a current status determination is not applicable.
    • Long Term Trends - The confidence in the long-term trend for the analysis of 11 data points (1989 to 2006) of the annual average PM10 concentration is “moderate,” with an S = -31, and a P = 0.01. However, because current data were not available between 2007 and 2011, confidence in the long-term trend is not applicable.
    • 5 Year Trend - The trend over the most recent 5 years could not be determined because data were not available.
    •  Overall Confidence - The overall confidence is not applicable (N/A) due to insufficient current status and trend data on annual average PM10 concentrations.
  • Human and Environmental Drivers - Particulate matter pollution consists of very small liquid and solid particles in the air. The primary sources of PM10 in the Lake Tahoe Basin are motor vehicles, paved and unpaved road dust, wood smoke, and construction dust.The ambient concentration of PM10 is dependent on meteorological conditions such as wind speed and atmospheric mixing.
  • Monitoring Approach – The monitoring record indicates that PM10 has been monitored at two locations in the Lake Tahoe Basin; Sandy Way in South Lake Tahoe, and at the casino core at Stateline, Nevada. Data from the Sandy Way site were collected, analyzed, and reported by the California Air Resources Board (CARB 2011a). Data from the Stateline, NV was collected, analyzed, and reported by the Nevada Division of Environmental Protection, and the U.S. Environmental Protection Agency.
  • Monitoring Partners– California Air Resources Board, U.S. Environmental Protection Agency, and Tahoe Regional Planning Agency.


  • Monitoring Plan
  • Conceptual Model


PM10 Monitoring Locations in the Lake Tahoe Basin

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Trend Charts

The annual average particulate matter less than or equal to 10 microns in size (PM10) concentration measured at the Stateline, NV and South Lake Tahoe, CA sites. Concentrations are considerably better than Nevada standards and slightly better than California standards since the late 1990s. The long-term trend for the South Lake Tahoe, California site shows rapid improvement over the 1989-2006 period of record. PM10 data were not collected between 2007 and 2010, and thus current status and trend of this indicator are unknown.
Source: U.S. Environmental Protection Agency, Air Data
Nevada Division of Environmental Protection

Additional Info


  1. California Air Resources Board website, April 26, 2011:http://www.arb.ca.gov/adam/.
  2. EPA methods for air quality monitoring: http://www.epa.gov/ttn/amtic/files/ambient/criteria/reference-equivalent-methods-list.pdf

Additional Information

  1. PM10 24 hour average Indicator
  2. CARB fact sheet on health effects: http://www.arb.ca.gov/html/fslist.htm#Health
  3. Conceptual Model: A conceptual model for Air Quality CO does not exist as of June 2011 and is anticipated to be developed in 2011.
  4. Monitoring Plan: A monitoring plan for Air Quality CO does not exist as of June 2011 and is anticipated to be developed in 2012
Last Updated on Monday, 05 November 2012 10:48