Air Monitoring

In order to observe and assess the status of air quality within Weld County, the Board of County Commissioners approved and successfully contracted the installation of three local air monitoring stations in December 2020. 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), began recording data in early 2021.

Each monitoring site continuously collects ozone and meteorological data. The 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.  

The Weld County Air Monitoring page posts the current meteorological dashboard for all three sites and the quarterly reports for the air contaminant data collected at each site. 

Weld County Monitoring Information

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.

The Missile Site Park and Orchard monitoring sites have also been incorporated into the National Atmospheric Deposition Program (NADP).  

For quarterly and annual monitoring reports, and research publications, visit the Weld County Air Quality Reports and Publications page.  

State Monitoring Information

Stay up to date on the State of Colorado's overall air quality monitoring, modeling, and data collected, by visiting: 

Federal Monitoring Information

AirNow provides a platform for national, tribal, state, and local agencies to contribute and present all monitoring data in one comprehensive platform.  For assistance in understanding and using AirNow's air quality index, refer to their monitoring guidance found at