Sometimes it's as much as 100 times higher. Mold, viruses, bacteria, and other microorganisms can make a building sick. These bugs hide in ductwork or lurk in water that's used in heating or cooling systems and humidifiers. Each time air passes through the ventilation system, the microorganisms are carried along. People with weakened immune systems can acquire a pneumonia-like illness that is highly resistant to medication.
Air born mold can bring on some nasty respiratory problems, including asthma and emphysema.
Many people spend as much as 90 percent of their waking hours in enclosed spaces. That can contribute to new forms of chronic illness. Some people develop serious allergies to the buildings in which they work or worship. Like office buildings, church buildings can be afflicted with physical problems such as bad air, improper humidity levels, temperature problems, or lack of natural light. As more churches construct windowless sanctuaries in tightly sealed buildings, with offices and classrooms in which windows are permanently shut, problems can increase.