In an effort to obtain and share up-to-date air quality data with the community, the City of Louisville is in the process of installing PurpleAir air quality sensors at City facilities. The City has also secured a discounted price for air quality sensors for residents who would like to add them to their homes. While Boulder County Public Health (BCPH) is the responsible entity in regards to air quality and public health matters, the City is listening to the concerns of residents about air quality and wants to provide as much data as possible.

What do PurpleAir sensors measure? PurpleAir sensors measure airborne particulate matter (PM). PM describes solid particles suspended in air; this includes dust, smoke and other organic and inorganic particles.

PurpleAir sensors use laser particle counters to count the number of particles by size and the count data to calculate mass concentrations of PM1.0, PM2.5 and PM10. PM10 refers to inhalable particles with diameters that are generally 10 micrometers and smaller; and PM2.5 refers to fine inhalable particles with diameters that are generally 2.5 micrometers and smaller.

How can I reduce my exposure to PM? You can track air quality at https://www.airnow.gov/. Every day the Air Quality Index (AQI) can tell you how clean or polluted your outdoor air is, along with associated health effects that may be of concern. The City’s sensors will be used to inform the AQI. The City will also have access to a PurpleAir map that will provide localized readings.

If you visit the Louisville map on https://www2.purpleair.com/, you can see that the air quality today is ‘good’ or ‘acceptable’, similar to the surrounding areas.

If the sensors indicate unhealthy or hazardous air quality, residents are encouraged to take the following precautions:

• Limit outdoor activity
• Wear an N95 mask (or better) if outdoors
• Keep windows and doors closed
• If you have an air conditioner, make sure that the fresh air intake valve is closed and the filter is clean
• Consider using a portable evaporative cooler within your hours to avoid pulling air pollution in

How can I get my own PurpleAir sensor? If you are interested in installing your own PurpleAir sensor on your property, you may purchase a unit by visiting https://www2.purpleair.com/. The City has secured a 10% discount for any residents who wish to purchase a sensor. Please use the promotional code BOCO when checking out.

For more information about air quality, read BCPH's latest air quality update from January 25.

Up to date information will continue to be made available on the City’s website LouisvilleCO.gov/MarshallFire and through email updates.