When Comfort Turns Risky How Air-Conditioning Systems Can Contribute to Sick Building Syndrome at Home

Most homeowners see air conditioning as a symbol of comfort—especially during hot summer months. But what if the same system designed to keep us cool could also be quietly affecting our health? Increasing research suggests that poorly maintained or improperly designed air-conditioning systems can contribute to Sick Building Syndrome (SBS)—a condition where occupants experience discomfort and health symptoms linked directly to time spent indoors.

Understanding Sick Building Syndrome

Sick Building Syndrome refers to a set of symptoms—such as headaches, dry eyes, sore throat, fatigue, and difficulty concentrating—that improve when individuals leave the building. While originally studied in office settings, today’s remote-work lifestyle means many people may be facing similar issues inside their own homes.

What the Research Shows

Recent studies have highlighted the role that air-conditioning and ventilation systems play in SBS:

• A study published in Environmental Health Perspectives found that fully air-conditioned buildings reported higher rates of nasal and eye irritation compared to naturally ventilated ones.

• A 2023 study involving 392 adults showed that those who used AC for more than six hours a day had significantly higher rates of symptoms:

  • 46% reported dry or itchy eyes

  • 43% experienced sore throats

  • 40% suffered from runny noses

  • 27% had frequent headaches

  • 23% felt persistent lethargy

• Researchers at the National Institutes of Health identified key environmental triggers: high CO₂ levels, poor ventilation, low humidity, and dirty HVAC systems—all of which increase SBS risks.

Why It Matters for Homeowners

In homes, central air systems often recirculate indoor air instead of bringing in enough fresh outdoor air. Over time, dust, allergens, and even volatile organic compounds (VOCs) can accumulate, especially if filters aren’t changed regularly. For large families or those working from home, the impact can be even greater—longer daily exposure means greater risk of developing chronic discomfort or respiratory issues.

Another factor is humidity. Systems that don’t manage moisture effectively can promote mold growth inside ducts or walls, introducing another layer of health risk.

Inspection Insights: What to Look For

As part of a Home Vantage Inspection, we focus not only on visible issues but also on what’s circulating through your home’s air.
Here are key points every homeowner should keep in mind:

• Ensure your HVAC system provides adequate fresh-air intake, not just recirculated air.

• Replace filters every 2–3 months, or more often if pets or allergies are present.

• Schedule annual professional maintenance to clean coils, ducts, and drain pans.

• Monitor indoor humidity (30–50%) to prevent both dryness and mold growth.

• If symptoms like headaches, fatigue, or irritation occur mostly while indoors, consider an indoor air quality test.

The Bottom Line

A well-cooled home doesn’t always mean a healthy home. Good indoor air quality requires balance—temperature control, ventilation, and cleanliness working together. By maintaining your air-conditioning system properly and ensuring it supports, not restricts, air exchange, you protect not only your comfort but your long-term health.