Common Indoor Air Pollutants

Indoor air contains a mix of particles, gases, and biological material. Understanding what's likely in your apartment air helps you make informed decisions about whether and how to address it.

Particulate Matter

Tiny particles suspended in air are categorized by size:

PM10 (Particles under 10 microns)

Includes dust, pollen, mold spores, and some pet dander. Visible as dust settling on surfaces. Can be filtered by most air purifiers.

PM2.5 (Particles under 2.5 microns)

Includes smoke particles, fine dust, and combustion byproducts. Not visible individually but can cause haze. HEPA filters capture these effectively.

Ultrafine Particles (under 0.1 microns)

Includes combustion products, some cooking emissions. Harder to capture but HEPA filters still work through diffusion mechanisms.

Common Sources:

• Cooking (especially frying and high-heat methods)
• Candles and incense
• Outdoor air infiltration
• Vacuuming and cleaning (briefly stirs up particles)
• Fabric fibers from clothing, bedding, furniture

Volatile Organic Compounds (VOCs)

Gases emitted from various materials and products. "Volatile" means they evaporate easily at room temperature.

Common VOCs:

• Formaldehyde: From pressed wood products, some textiles, adhesives
• Benzene: From gasoline (attached garages), paints, tobacco smoke
• Toluene: From paints, adhesives, nail polish
• Xylene: From paint, lacquer, rust preventatives

Sources in Apartments:

• New furniture and cabinetry (off-gassing)
• Paint and finishes
• Cleaning products
• Air fresheners and scented products
• Personal care products
• Building materials

VOCs generally decrease over time as products "off-gas." New apartments or recently renovated spaces have higher levels initially.

Carbon Dioxide (CO2)

We exhale CO2 with every breath. In well-ventilated spaces, it disperses harmlessly. In enclosed spaces, it accumulates.

What High CO2 Indicates:

Primarily an indicator of ventilation quality. Elevated CO2 (above 1000-1500 ppm) suggests inadequate fresh air exchange. You might feel stuffy, drowsy, or find it harder to concentrate.

Note:

CO2 at typical indoor levels isn't dangerous—it's a ventilation marker, not a toxin at these concentrations. Opening windows or improving airflow addresses it.

Carbon Monoxide (CO)

A dangerous, odorless gas from incomplete combustion. Sources include:

• Gas stoves and appliances
• Attached garages
• Malfunctioning heating systems

Every home with gas appliances should have CO detectors. Air purifiers don't remove CO—only ventilation and source control work.

Biological Contaminants

Dust Mites

Microscopic creatures that feed on skin flakes. Live in bedding, upholstered furniture, and carpets. Their waste products are a common allergen.

Mold Spores

Fungi that reproduce via airborne spores. Thrive in humid conditions. The spores themselves can trigger reactions in sensitive individuals.

Pet Dander

Skin flakes from cats, dogs, and other pets. Remains airborne for hours and settles on surfaces. Can persist long after pets are gone.

Pollen

Enters through open windows and on clothing. Seasonal but can be significant for allergy sufferers.

What Can You Do?