Everything from mold, to cigarette smoke, to chemicals, and even carbon monoxide from a malfunctioning heating system, can make indoor air quality unpleasant at minimum and deadly at worst. Here are seven statistics relating to indoor air quality:

1. Three common causes of poor indoor air quality are improperly or inadequately maintained heating and ventilation systems; contamination of air by chemicals, glues, paints, etc; and insufficient intake of fresh outdoor air.
2. Nine health-related symptoms related to poor air quality in a workplace include eye, nose and throat irritation; fatigue; headache; shortness of breath; allergies; coughing/sneezing; sinus congestion; dizziness; and nausea.
3. One sign that your workplace has an air quality issue is that you feel healthier hours after leaving work; such as on a day off—and physically worse a few hours after returning to work.
4. A recent heating system malfunction at a label-printing plant in North Royalton, OH, sent 13people to hospital for treatment of carbon monoxide poisoning.
5. Three unsuitable locations for outdoor air intakes that can result in pollution being sucked into a building are loading bays, parking garages and cooling tower enclosures.
6. Six essential elements of a preventive maintenance program to ensure good indoor air quality include regular inspections of all critical components of the ventilation system; regular inspections for conditions such as water leaks or stagnant water pools that would promote the growth of micro-organisms; correction of any deficiencies found; repair or replacement of malfunctioning components, such as filters and belts, and cleaning of air distribution systems, ducts and dampers; adequate treatment of open-water systems associated with ventilation systems, such as cooling towers and humidifiers; and maintenance of furnaces, space heaters and water heaters to ensure proper burning and exhausting of waste gases.
7. Three situations which should trigger an indoor air quality investigation are: complaints from workers; substantial increases in building occupancy; and building renovations that involve significant changes to the ventilation system.