An Invisible Threat
We spend approximately 90 percent of our time indoors, yet most people never think about the air they breathe at home and work. Poor indoor air quality (IAQ) is linked to a wide range of health problems, from daily annoyances to serious chronic conditions.
Short-Term Effects
Symptoms that appear within hours or days of exposure to poor indoor air:
- Headaches and fatigue — often attributed to stress or lack of sleep, but frequently caused by elevated CO2 levels above 1,000 ppm
- Eye, nose, and throat irritation — triggered by VOCs, dust, and low humidity
- Difficulty concentrating — research shows cognitive performance drops significantly in stuffy rooms
- Allergic reactions — mould spores, dust mites, and pet dander thrive in poorly ventilated, humid environments
Long-Term Health Risks
Chronic exposure to poor IAQ is associated with far more serious conditions:
- Respiratory disease — asthma, bronchitis, and chronic obstructive pulmonary disease (COPD) are all worsened by indoor pollutants
- Cardiovascular disease — long-term PM2.5 exposure increases heart attack and stroke risk
- Cancer — radon, formaldehyde, and benzene (common indoor pollutants) are classified carcinogens
- Neurological effects — emerging research links chronic poor air quality to faster cognitive decline in older adults
Sick Building Syndrome
The WHO defines Sick Building Syndrome (SBS) as a condition where building occupants experience acute health effects linked to time spent in a building, with no specific illness identified. Symptoms typically improve after leaving. Poor ventilation with high CO2 is a consistent feature of SBS buildings.
What You Can Do
- Start monitoring — you cannot fix what you cannot see. A CO2 monitor is the most accessible first step. See our best home monitors.
- Improve ventilation — follow our budget ventilation guide for practical, affordable strategies.
- Address specific pollutants — use HEPA filtration for particles, ventilation for CO2, and source control for VOCs.
- Monitor bedroom air — sleep quality is profoundly affected by overnight CO2 accumulation.
- Learn the basics — our IAQ beginner guide covers all the fundamentals.
Use the CO2 calculator to assess whether your current ventilation is adequate for your space and occupancy.