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Air Quality Reports

The San Luis Obispo County Air Pollution Control District (APCD) prepares a variety of reports on air quality monitoring performed at various sites throughout the county, including annual reports summarizing air quality data collected for a given year; reports on special air quality monitoring studies conducted for a specific purpose; long-term air quality trend analyses; and mandated reports on our air quality monitoring network. The various reports are presented below.

Annual Report

The Annual Air Quality Report describes the network of air monitoring sites operated in the county for that calendar year (occasionally 2 years are combined); the different pollutants measured at each site; the state and federal health standards that must be met for each pollutant; the three highest concentrations measured for each pollutant at each site during that year; and trend charts presenting several years of concentration data for both ozone and particulate matter, the two pollutants of most concern in our county.

Current and historical Annual Air Quality Reports are available below1.

Click here to view the full 2022 Annual Air Quality Report.


Previous Annual Air Quality Reports

2021 Annual Air Quality Report | Infographic
2020 Annual Air Quality Report | Infographic
2019 Annual Air Quality Report | Infographic
2018 Annual Air Quality Report | Infographic
2017 Annual Air Quality Report | Infographic
2016 Annual Air Quality Report
2015 Annual Air Quality Report
2014 Annual Air Quality Report
2013 Annual Air Quality Report
2012 Annual Air Quality Report
2010 - 2011 Annual Air Quality Reports
2008 - 2009 Annual Air Quality Reports
2007 Annual Air Quality Report
2006 Annual Air Quality Report
2005 Annual Air Quality Report
2004 Annual Air Quality Report
2003 Annual Air Quality Report
2002 Annual Air Quality Report
2001 Annual Air Quality Report
2000 Annual Air Quality Report
1999 Annual Air Quality Report

South County Air Quality Reports

The APCD has conducted several studies to evaluate the high particulate matter concentrations measured in the South County and to develop potential solutions to the dust emissions from the Oceano Dunes that are impacting downwind neighbors. To see all of the study reports and the data collected, please visit the links below. 

Revisions to Forecast Zones Report, May 2021

Community Air Monitoring in Oceano, California

South County Community Monitoring Project

Phase 2 Study

Phase 1 Study

Air Quality monitoring has been conducted in San Luis Obispo since 1970. Comparison of our monitoring data against the California state standards for multiple year periods provides us with a good indicator of how our air quality is improving.

Air Quality Trends Report: 1991- 2011

The Air Quality Trends Report analyzes trends in ozone and particulate matter measurements from 1991 through 2011. Emission reduction strategies implmented by the District and other air agencies statewide have resulted in significant improvements in air quality in most areas of the county during this period, despite considerable increases in population and vehicle miles traveled. Ozone levels have fallen countywide, and airborne particulate levels have also declined significantly in most areas except the south county. In-depth analysis of numerous statistical indicators and other measures of long-term air quality trends are presented in the report. 

Staff Report to the Board and Final Air Quality Trends Report

Contact us for more information on this topic.


  1. Since 2010, the District has been upgrading and standardizing our data compilation and analysis methods, including improvements to data accuracy by switching to electronic data tabulation rather than the manual count method used previously. A comprehensive review of the data presented in previous annual reports was also conducted to identify and correct any data discrepancies compared to current methods; this review revealed some tabulation errors in the pollutant trend charts presented in reports prior to 2010. Addenda have been added to the 1999-2009 Annual Reports to correct those errors; a detailed discussion in the 2008-2009 Annual Report and referenced in the other reports describes the specific errors corrected and some of the new data review and presentation protocols now in place.