Q: What Can Generate Indoor PM?

Indoor PM (particulate matter) comes from a combination of indoor sources and outdoor infiltration. Indoor sources of PM can be emitted through a number of common activities. At the same time, outdoor infiltration occurs when PM generated outside the house infiltrates indoor spaces through windows, doors, and other openings. These sources can affect indoor air quality.

This article is not exhaustive. For in-depth information about indoor PM, please check out the EPA’s page at Indoor Particulate Matter | US EPA


Indoor Sources

Despite what some might believe, indoor air isn’t always clean. There are a number of indoor sources of PM that can affect your air quality. Some examples could include cooking, cleaning, pets, or the use of candles and fireplaces. Further examples can be found here: Sources of Indoor Particulate Matter (PM) | US EPA

In addition to the sources that the EPA has identified, ultrasonic humidifiers have been found to generate indoor PM. More information about ultrasonic humidifiers can be found here: Ultrasonic Humidifiers


What Can Help?

The following tips can help with poor air quality. However, this is a complex topic. While we can provide advice on how to best use PurpleAir sensors, we cannot advise on medical or health-based decisions and do not claim to be air quality experts.

  1. If you have identified a source of PM within your home using the resources above, you can focus on eliminating or limiting that source.

  2. If your building has an HVAC system, you can turn it on and let it cycle air through the building.

  3. You can create a DIY Box Fan Air Purifier. This involves connecting an air filter to the intake side of a box fan. Then, when air is pulled through the fan, particulates become trapped in the filter.

  4. If outdoor air quality is better than indoor air quality, you can open a few windows to improve airflow and lower indoor PM levels. It’s important to note that PurpleAir sensors primarily measure PM, which is only one component of air quality.


Learn More

Air Quality Index (AQI)
Which Sensor to Choose
Why Should I Put My Indoor Sensor on the Map