Indoor air quality monitors deployed across multiple U.S. homes over several months have revealed unexpected data shifts tied to common household appliances and environmental conditions, according to findings reported by CNET wellness and smart home experts.
Humidity Spikes and PM2.5 Readings
When running a humidifier to relieve sinus congestion, CNET contributor Anna Gragert observed that air quality monitors in Los Angeles consistently registered high particulate matter readings, turning indicator lights red. According to Joakim Lindh, head of strategic growth at Airthings, this reaction occurs because dust and smoke particles are hygroscopic, meaning they absorb moisture from humid air. When humidity levels rise, these particles swell in size, causing particulate matter monitors to register higher values. Airthings recommends maintaining indoor humidity between 40% and 60% to prevent these fluctuations and to keep dust mites from thriving in damp environments.
Combustion Appliances and VOC Increases
Monitoring data from the same Los Angeles location showed that volatile organic compounds, or VOCs, increase sharply whenever a gas stove or oven is used. According to the U.S. Lindh explains that gas cooking relies on combustion, which burns off natural gas to generate heat. This chemical reaction releases pollutants into living spaces, including ultrafine particulate matter, nitrogen oxides, and carbon monoxide. Furthermore, research indicates that unburned methane and other harmful gases can leak from stoves even when the appliances are turned off.
Carbon Dioxide Accumulation from Daily Living
Similarly, air monitors placed near kitchens and living areas capture elevated CO2 and pollutant spikes during routine cooking and heating activities using gas appliances and fireplaces.