Weld County has been collecting ambient air data since early 2021. These monitors use high-quality equipment that meets federal standards; however, it cannot be used directly for regulatory decisions. Our local air quality monitors complement existing regulatory monitoring efforts by the Air Pollution Control Division by filling in data gaps within our very large county. The data collected from our monitors helps in decision-making, such as determining the boundaries of non-attainment areas, and can also provide a "reality check" for air quality models.
The monitoring stations, located at the Missile Site Park (west of Greeley), in Hereford (near the Wyoming border), and in Orchard (at the Weld and Morgan County border), collect ozone and meteorological data. Missile Site Park also collects data on ozone precursors, specifically nitrogen oxides (NOx), and currently hosts a volatile organic compounds (VOC) monitor for the Colorado Department of Public Health and Environment's Air Pollution Control Division.
Additionally, the Missile Site Park and Orchard sites serve as monitoring sites for the National Atmospheric Deposition Program (NADP), which partners with local stakeholders to collect field samples of nitrogen deposition (NTN program) and ammonia (AMoN) in order to track and observe trends across the country.
Weld County Environmental Health Specialists visit the Missile Site Park and Orchard sites weekly and the Hereford site bi-weekly, to collect samples and perform site and equipment maintenance.
For questions on the Weld County air quality monitoring network, please contact Environmental Health Director, Dan Joseph, at djoseph@weld.gov.
The three commissioned Weld County air monitoring sites (Missile Site Park, Orchard, and Hereford) were installed and are maintained in accordance with EPA’s Quality Assurance Handbook for Air Pollution Measurement Systems. All systems undergo comprehensive accuracy and performance audits, calibrations, and data analysis by Ramboll US Consulting, Inc. Local meteorological data from these sites will be collected every 15 minutes and available on the Weld County Meteorological Dashboard.
Monitoring reports can be found below:
Reports for 2021 and 2022, and the validated data presented in all reports, can be requested by contacting (970) 400-6415.
The Weld County Air Quality Network's Quality Assurance Project Plan (QAPP)(PDF, 12MB) outlines the procedures used to ensure data collected and analyzed meets projects goals and follows EPA guidance and requirements.
Stay up to date on the State of Colorado's overall air quality monitoring, modeling, and data collected, by visiting:
You can also download the AirNow Mobile App, which includes the AirNow Fire and Smoke map for information on wildfire smoke and air quality.
Air quality sensors have become popular and widely used by the public because they are lower cost, portable, and generally easier to operate than regulatory-grade monitors. These sensors provide valuable insights into local pollution patterns, helping individuals take steps to protect their health.
For more information on the difference between sensors and monitors, check out these EPA videos available in English and Spanish.
Local meteorological data from the Missile Site Park, Hereford, and Orchard air monitoring sites is collected every 15 minutes and available on the Weld County Meteorological Dashboard.