As we head into the hot and dry summer months of July and August, wildfires become more and more likely, with winds that can carry ash and smoke great distances. Air particulates like ash and debris can travel right to our doorsteps and cause some community members, especially those with cardiovascular and respiratory issues, to experience adverse health effects, such as difficulty breathing, coughing, and wheezing.
WSCC tracks air quality using a PurpleAir sensor mounted at our office in Paonia, CO. The sensor uses laser light scattering to measure the number and size of particles in the air and then rates the air quality according to the Air Quality Index (AQI).
The AQI is a measurement scale used to report the levels of common air pollutants in the air. The AQI provides a standardized way of communicating air quality information to the public that is easy to understand and helps people make informed decisions about their health and activities.
The AQI measures 5 common air pollutants that can negatively impact human health:
- Ground-level Ozone
- Particulate Matter (PM2.5 and PM10)
- Carbon Monoxide (CO)
- Sulfur Dioxide
- Nitrogen Dioxide
The AQI ranges from 0 to 500, with higher values indicating poorer air quality. The AQI scale in the US, for example, has 6 categories.
Each category represents a different level of health concern:
- Good (0-50)
- Moderate (51-100)
- Unhealthy to Sensitive Groups (101-150)
- Unhealthy (151-200)
- Very Unhealthy (201-300)
- Hazardous (301-500)
To monitor the air quality in Paonia and find other PurpleAir monitoring locations in the North Fork area and beyond you can follow this link for up to date information and air quality reports.
If you’d like to learn more about how PurpleAir sensors work to sample and analyze air quality, you can read more on their website here!
Air Quality Index Average for Paonia from July 13-15, 2025
The graph above shows the average AQI from July 13-15, 2025. During this time, wildfires along the Black Canyon Rim and west of Delta caused spikes in the size and quantity of particulates in the air picked up by the sensor. You may notice that there are two channels of data represented, Western Slope Conservation Center A and Western Slope Conservation Center B. This is because PurpleAir sensors are equipped with two laser counters which take separate measurements in order to compare the correlation of these two channels to create a measure of confidence—called the Confidence Score—that serves as an assurance of data quality. For example, the spike on channel A on July 13 does not seem to have been picked up by both counters, and so may be an anomaly or error. The number 37.6 shown at the right of the graph is the total average AQI of both channels for the three day span.
Data from the sensor is sent to the PurpleAir servers every two minutes. The graph above shows the default ten minute average, meaning that the data points show the average AQI for each ten minute interval. This graph can be adjusted to show averages by the hour, week, or even year by changing the graph settings.