Indoor air can contain a mix of invisible and often harmful substances. These include particulate matter (PM), such as dust, pet dander, smoke, and mold spores. PM2.5—tiny particles less than 2.5 microns wide—are especially concerning because they can travel deep into the lungs and even enter the bloodstream. These particles come from cooking, candles, wood burning, and even printer use.

Another category is volatile organic compounds (VOCs)—gases released from everyday items like paints, cleaning supplies, air fresheners, and even furniture. These chemicals can irritate the eyes and lungs and may affect the nervous system over time. Then there are biological contaminants, like bacteria, viruses, mold spores, and pollen. These can trigger allergic reactions or worsen respiratory conditions. Recognizing these sources is the first step toward taking control of what we breathe indoors.