Indoor air often contains pollutants that can cause headaches, fatigue, or longer-term health problems. Poor ventilation, off-gassing from furnishings, and excess humidity all contribute to discomfort. Monitoring your indoor air quality (IAQ) helps you identify when to increase ventilation, add air purifiers, or address moisture issues. A single score simplifies the process, letting you compare rooms or track improvements after taking action.
Three major factors influence the IAQ score in this calculator: carbon dioxide (CO2), relative humidity, and volatile organic compound (VOC) concentration. Elevated CO2 often signals that air is stagnant, which can impair concentration and alertness. High or low humidity affects comfort and can encourage mold growth. VOCs, emitted by paints, cleaners, and furniture, may cause irritation or long-term health concerns. By measuring these values, you gain insight into the freshness of your indoor environment.
To combine these variables into a single rating, we use the formula
where is CO2 in parts per million, is humidity percentage, and represents VOC concentration. The formula penalizes higher CO2, deviation from ideal humidity (around 45%), and elevated VOCs. Scores range from 0 (stale air) to 100 (fresh air).
| Score Range | Air Quality |
|---|---|
| 80-100 | Excellent |
| 60-79 | Good |
| 40-59 | Fair |
| Below 40 | Poor |
Use this table as a reference. If your score consistently falls below 60, consider increasing ventilation, checking for mold, or reducing sources of VOCs.
Everyday activities can degrade air quality faster than you might think. Cooking on gas stoves releases CO2 and other gases. Cleaning solutions and new furnishings emit VOCs. Even simple breathing increases CO2 in tightly sealed homes. Dry climates may push humidity too low, while bathrooms and kitchens can become excessively humid. Awareness of these sources helps you take steps to improve air circulation and minimize pollutants.
Keeping carbon dioxide under 1000 ppm is ideal for comfort. Opening windows, using exhaust fans, or installing a heat recovery ventilator can move stale air out while bringing fresh air in. Plants can help to a limited extent, but they’re not a replacement for proper ventilation. If you live in an area with poor outdoor air quality, consider filtration systems that allow you to ventilate without inviting pollutants from outside.
Humid air encourages mold and dust mites, while dry air leads to sore throats and static electricity. Aim for 40%-50% humidity by using dehumidifiers or humidifiers as needed. In damp climates, pay attention to condensation on windows and walls—it’s a sign moisture is lingering. Kitchens and bathrooms benefit from vent fans to remove steam quickly. Monitoring humidity alongside CO2 keeps your IAQ score from dropping due to moisture issues.
Volatile organic compounds come from paint, cleaning products, and new furniture or flooring. Whenever possible, choose low-VOC alternatives and let new items off-gas outside before bringing them indoors. Keep chemicals sealed and stored in a well-ventilated area. Regular ventilation, especially after using strong cleaners or installing new materials, prevents VOC buildup that could otherwise lower your air quality score.
After making changes such as adding an air purifier or improving ventilation, rerun the calculator to see how your score changes. Monitoring trends over weeks or months reveals whether your efforts are paying off. You might find that a small tweak—like opening windows for ten minutes each morning—has a significant impact. Keeping a log of scores helps you understand how seasonal changes or lifestyle habits influence indoor air.
An air quality score empowers you to make more informed decisions about your living space. If the score is low, you’ll know to clean or replace air filters, reduce pollutant sources, or adjust humidity levels. A high score confirms that your home is well ventilated and comfortable. Ultimately, the goal isn’t perfection but awareness: by measuring your IAQ, you take control of your environment and support your well-being.
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