How to tell if the air in your house is making you sick?

You can tell if the air in your house is making you sick by looking for patterns of symptoms that improve when you leave the house and worsen when you return, along with visible signs of air quality problems. Common symptoms of poor indoor air include frequent headaches, dizziness, fatigue, difficulty concentrating, irritated eyes, nose, and throat, frequent coughing, sneezing, worsening asthma or allergies, and respiratory infections that do not go away. If you notice mold spots on walls, ceilings, or windowsills, musty odors, excessive dust, condensation on windows, or high humidity above 60 percent, these are signs of mold and dust mite growth that can make you sick. Another clue is if multiple household members develop similar symptoms at the same time, or if symptoms are worse in certain rooms like basements. You can also watch for signs like carbon monoxide detector alerts, gas smells, or symptoms like nausea that could indicate chemical contamination from cleaning products, new furniture off-gassing formaldehyde, or radon. To confirm, you can get an indoor air quality monitor that measures PM2.5, VOCs, humidity, and CO2, hire a professional for mold testing, and keep a symptom diary noting when you feel worse. Improving ventilation, using HEPA air purifiers, fixing leaks, controlling humidity below 50 percent, and avoiding smoking indoors can greatly improve air quality and health.