By Julia Bakker-Arkema and Marina Vance.

This video was entered in the 2019 AAAR conference video competition and won 1st prize! Congratulations to Julia and Nina.

We see and experience particulate matter, or aerosol particles, all around us.

Aerosol particles make up the smog we see on our morning commutes, the trails of smoke that rise out of our campfires, and the sea spray that fills the air after a wave crashes against a rock. They’re at the center of each and every cloud droplet and in puffs of smoke from cigarettes. But did you know that we also encounter aerosols indoors? We might not typically associate aerosols with indoor spaces, but many research studies have detected a variety of particles in the indoor environment.

So where do indoor aerosols come from? Maybe the most obvious source is when outdoor aerosols travel indoors. Air enters homes and other buildings through doors, windows, ventilation systems, and leaks and cracks in the building envelope. The closer a building is to major outdoor aerosol sources, like busy roads with lots of traffic, the more particles may end up inside.

Some aerosol particles have indoor sources as well. A few examples of indoor activities that can generate particles are burning incense, lighting candles, or any other form of combustion really, as well as using office products, like printers and 3d printers.

But one of the most important indoor aerosol sources is your kitchen. Roasting a chicken, preparing a stir-fry, and other cooking activities generate large amounts of particles indoors, especially when using a gas stove. With so many surfaces inside, like the floors, walls, furniture, and carpet, particles are lost more quickly indoors than they would be outdoors because they stick to surfaces or settle due to gravity.

But the particles we see inside, especially those generated from human activities like cooking, have the opportunity to influence our indoor air quality, and potentially react further by changing the chemistry of the indoor environment. While we know about many sources of particles indoors, researchers are still working to understand their role in indoor chemistry and human health.

So what can you do? To limit your exposure to aerosols, ventilate your kitchen while cooking, look at websites like to learn more about outdoor air quality before opening windows and reconsider your habits when it comes to burning candles and other activities that can affect your indoor air quality.