Workers in Buildings with Less Fresh Air More Likely to Call in Sick
In 1988, Donald Milton, associate professor in the Department of Environmental Health, was working as a consultant for a health care clinic when he noticed that there was a 10-fold difference in absentee rates of workers between specific buildings.
Intrigued, Milton hypothesized that the difference may be connected to the nature of the air the employees breathed. He was unable to study the phenomenon at the company but a few years later found an opportunity to test his hypothesis at the Polaroid Corporation.
The result of that testing was published in the current issue of Indoor Air in a paper, "Risk of Sick Leave Associated with Outdoor Air Supply Rate, Humidification, and Occupant Complaints."
In 1994, Milton and two colleagues measured ventilation rates in 40 buildings owned by Polaroid in Massachusetts with 115 independently ventilated work areas. They quantified air supply as moderate or high and then analyzed the absences of more than 3,700 employees to see who had called in sick and in which areas they worked.
After noting a correlation between absences and the amount of ventilation in work areas, the researchers narrowed their focus to 600 office workers because they were less likely to be exposed to airborne irritants than those employed in manufacturing areas.
The researchers used sick leave records only of employees not on long-term disability. After considering factors such as age, gender, and number of times employees took off when they were not ill--such as vacation days--the researchers found that office workers employed in areas that were moderately ventilated were 53 percent more likely to take time off due to illness than their colleagues in highly ventilated areas. Increasing ventilation may have prevented 35 percent of the absences, reported the researchers.
Milton suggested that the increased absences may result from the transmission of cold and flu viruses and other irritants that are not removed in ventilation systems with moderate airflow.
The researchers calculated that the absences cost the company an average of $480 per worker per year. When the researchers extrapolated the data and applied the numbers to the US working population as a whole, they estimated that American companies lose as much as $22.8 billion each year to lost productivity resulting from poor ventilation. The losses may be curtailed by increasing air circulation in buildings, Milton said, but he added that net savings may be chipped away by rising energy costs. Companies may want to search for alternative means of cleaning the air they recycle in their buildings, he said.
"I think over the next 10 to 15 years it will be important to know why we see this association between ventilation and sick leave," said Milton. "We need to figure out what we can do as energy costs go up that is cost effective but still protects the health and productivity of workers."
