How to Improve Indoor Air Quality

The air inside your home can be two to five times more polluted than the air outside, according to the Environmental Protection Agency. Most Americans spend 90 percent of their time indoors, making indoor air quality a significant factor in respiratory health, sleep quality, and overall well-being.

Understanding Indoor Air Pollutants

Common indoor pollutants include:

Particulate matter — Dust, pollen, pet dander, mold spores, smoke particles
Volatile Organic Compounds (VOCs) — Chemicals from paints, cleaning products, furniture, and building materials
Biological contaminants — Mold, mildew, bacteria, dust mites
Combustion byproducts — Carbon monoxide, nitrogen dioxide from gas stoves and furnaces
Radon — A naturally occurring radioactive gas that seeps into homes

The three pillars of indoor air quality improvement are source control, ventilation, and filtration.

Source Control: Stop Pollutants at the Source

Reduce VOC Emissions

Choose low-VOC or zero-VOC paints, stains, and finishes
Opt for solid wood furniture over pressed wood products
Store chemicals in a detached garage or shed
Use natural cleaning products
Air out new furniture and carpets before bringing them into living spaces

Control Moisture and Mold

Keep indoor humidity between 30 and 50 percent
Use exhaust fans in bathrooms and the kitchen
Fix plumbing leaks promptly
Ensure proper grading around your foundation
Use a dehumidifier in damp basements and crawl spaces
Clean water damage within 24 to 48 hours

Minimize Combustion Byproducts

Have gas furnace, water heater, and fireplace inspected annually
Ensure proper venting for all combustion appliances
Install carbon monoxide detectors on every level and near sleeping areas — the Google Nest Protect Smoke and CO Alarm provides smart alerts and a 10-year sealed battery
Consider switching to an electric or induction cooktop

Ventilation: Bring in Fresh Air

Natural Ventilation

Open windows and doors when weather permits. Even 10 to 15 minutes of cross-ventilation can significantly reduce indoor pollutant concentrations.

Mechanical Ventilation

Exhaust fans — Run bathroom fans during and 30 minutes after showering. Use the range hood when cooking.
Energy Recovery Ventilators (ERVs) — Exchange stale indoor air with fresh outdoor air while transferring heat and moisture
Heat Recovery Ventilators (HRVs) — Similar to ERVs but without moisture transfer, best for colder climates

Filtration: Capture What Remains

Upgrade Your HVAC Filter

Upgrading to a pleated MERV 11 or MERV 13 filter captures significantly more particles. Check your system’s specifications before upgrading beyond MERV 11. The Filtrete 1500 MPR Smart Air Filter (MERV 12) is a popular balance between effective particle capture and acceptable airflow for most residential systems.

Portable Air Purifiers

For bedrooms, home offices, and nurseries, a portable air purifier with a true HEPA filter can remove 99.97 percent of particles 0.3 microns and larger. Look for models sized appropriately for the room, measured by Clean Air Delivery Rate (CADR). The Levoit Core 300 Air Purifier is a compact, quiet, and well-reviewed HEPA option for rooms up to 219 square feet.

Whole-House Air Purifiers

Installed within your ductwork, these systems treat all circulating air. Options include media filters, electronic air cleaners, UV-C light systems, and activated carbon filters.

Monitor Your Air Quality

Consumer-grade air quality monitors provide real-time data on particulate matter, VOCs, humidity, temperature, and carbon dioxide levels. This data helps you adjust your ventilation, filtration, and humidity control strategies.

Seasonal Considerations

Spring and Summer

Keep windows closed on high-pollen days
Change HVAC filters more frequently during heavy AC use
Monitor humidity and use dehumidifiers as needed

Fall and Winter

Replace furnace filters before heating season
Ensure carbon monoxide detectors have fresh batteries
Use ERV or HRV systems to maintain fresh air without losing heat

Improving indoor air quality is an ongoing practice. By combining source control, ventilation, and filtration, you can significantly reduce your exposure to indoor pollutants and create a healthier home environment.