The indoor environment is complex as are the mechanical factors involved.

Heating, Ventilation and Air Conditioning systems (aka, HVAC units) are often poorly managed for heating and cooling: vents may be blocked; moisture levels unmonitored; ventilation lacking; and the open/closed status of windows or doors not integrated into a thoughtful plan.

Spotty system maintenance—coupled with inadequate lighting and improper storage of materials—produces unhealthy conditions.

The main solution is a program of systematic care of HVAC systems which lowers operating costs while improving the health of occupants.

(Adapted from: Protecting the Built Environment – Cleaning for Health, by Dr. Michael Berry, published in 1994.)