Annual Data Quality Report for CARB's PQAO
Download the 2024 Annual Data Quality Report for CARB’s Primary Quality Assurance Organization (PQAO) using the link at the bottom of this webpage. To request reports from previous years, please email: qa@arb.ca.gov.
Overview
The 2024 Annual Data Quality Report for CARB's PQAO (2024 Annual Report) provides ambient air quality data producers and users with a centralized review of the data quality within CARB’s PQAO. The data are described in quantifiable terms in relation to measurement quality objectives (MQO) established by United States Environmental Protection Agency (U.S. EPA) and summarized for ambient air monitoring stations in the statewide network within CARB’s PQAO. CARB’s PQAO data are also compared to other PQAOs in California and the nationwide average, where appropriate. Any data quality assessments are solely based on certified data available in U.S. EPA’s Air Quality System (AQS).
Background
U.S. EPA designated CARB as one of seven PQAOs in California responsible for monitoring air pollutants and assessing data quality. The 2024 Annual Report focuses on four PQAOs (CARB, Bay Area Air Quality Management District, San Diego Air Pollution Control District, and South Coast Air Quality Management District) in California, which encompass most of the geographic area and population in the State. Within CARB’s PQAO, there are 22 monitoring organizations with air monitoring sites.
Data Quality
Data quality is assessed using the following MQOs.
- Ambient data capture rate, which is the percentage of ambient data collected and reported to U.S. EPA's Air Quality System (AQS) compared to the total expected data.
- Precision, which is the degree of mutual agreement among repeated individual measurements of the same property.
- Bias, which is the systematic or persistent distortion of a measurement process which causes error in one direction.
- The amount of precision and bias data collected and reported.
Data quality is presented for two types of pollutants: gaseous and particulate matter.
Data Quality Results
View the 2024 Conclusions and Recommendations for a high-level summary.
For more details, select an option below to view your preferred dataset: a detailed view of 2024 data, or a comparison of historical data. Data quality results shown for 2024 reflect certified data available in AQS as of July 2025. Note that the 2022 and 2023 data quality results shown may not reflect current information in AQS due to potential data reporting to AQS occurring after the reports for these years were published.
Download the 2024 Annual Data Quality Report for CARB’s PQAO using the link below. To request reports from previous years, please email: qa@arb.ca.gov.