Uploaded June 2023 | Updated September 2026, 1 hour ago
The summer of 2021 was a smoky one for Denver and northeastern Colorado. Smoky haze from wildfires in Arizona, California, and the Pacific Northwest shrouded the Front Range mountains and cast a gray pallor over the sky on a near-daily basis.
This video shows the path of wildfire smoke as it moved eastward across the United States during early August 2021, and a timelapse video of smoke settling over downtown Denver on August 7, which turned out to be the smokiest day of the year. The typical summer thunderstorms that flush out stagnant air in July and August largely failed to materialize, allowing smog cooked under the summer sun to pool along the foothills of the Rocky Mountains.
A new study by CIRES and NOAA researchers finds smoke from those wildfires led to days when Denver’s ground-level ozone exceeded the EPA standard of 70 parts per billion. Their results show that during the month of July, there were 12 days when ozone levels exceeded the EPA standard when they wouldn’t have if there were no smoke. The researchers caution that the likelihood of more smoke in more places highlights the need for effective public health communication - because although wildfire smoke can be seen with the naked eye, ozone is invisible.
Video produced by CIRES; smoke transport imagery created by the NOAA Global Systems Laboratory HRRR smoke model; timelapse imagery of Denver courtesy of the Colorado Department of Public Health and Environment. Links to more information and resources are below.
A NOAA news story about this research:
research.noaa.gov/2023/06/20/smoked-out-were-wildfires-responsible-for-denvers-record-ozone-season-of-2021/#
The new study describing summer 2021 ozone pollution in Denver:
agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022JD037700
NOAA High-Resolution Rapid Refresh (HRRR) smoke model made by the Global Systems Laboratory:
hwp-viz.gsd.esrl.noaa.gov/smoke/index.html#
Global Systems Laboratory website:
gsl.noaa.gov
Timelapse videos of downtown Denver made by Colorado Department of Public Health and Environment:
colorado.gov/airquality/live_image_tl.aspx
The summer of 2021 was a smoky one for Denver and northeastern Colorado. Smoky haze from wildfires in Arizona, California, and the Pacific Northwest shrouded the Front Range mountains and cast a gray pallor over the sky on a near-daily basis.
This video shows the path of wildfire smoke as it moved eastward across the United States during early August 2021, and a timelapse video of smoke settling over downtown Denver on August 7, which turned out to be the smokiest day of the year. The typical summer thunderstorms that flush out stagnant air in July and August largely failed to materialize, allowing smog cooked under the summer sun to pool along the foothills of the Rocky Mountains.
A new study by CIRES and NOAA researchers finds smoke from those wildfires led to days when Denver’s ground-level ozone exceeded the EPA standard of 70 parts per billion. Their results show that during the month of July, there were 12 days when ozone levels exceeded the EPA standard when they wouldn’t have if there were no smoke. The researchers caution that the likelihood of more smoke in more places highlights the need for effective public health communication - because although wildfire smoke can be seen with the naked eye, ozone is invisible.
Video produced by CIRES; smoke transport imagery created by the NOAA Global Systems Laboratory HRRR smoke model; timelapse imagery of Denver courtesy of the Colorado Department of Public Health and Environment. Links to more information and resources are below.
A NOAA news story about this research:
research.noaa.gov/2023/06/20/smoked-out-were-wildfires-responsible-for-denvers-record-ozone-season-of-2021/#
The new study describing summer 2021 ozone pollution in Denver:
agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022JD037700
NOAA High-Resolution Rapid Refresh (HRRR) smoke model made by the Global Systems Laboratory:
hwp-viz.gsd.esrl.noaa.gov/smoke/index.html#
Global Systems Laboratory website:
gsl.noaa.gov
Timelapse videos of downtown Denver made by Colorado Department of Public Health and Environment:
colorado.gov/airquality/live_image_tl.aspx
