Published: 1981 | Digest of the 3rd CMBFS Canadian Clinical Engineering Conference

Winter humidities and related absenteeism in Canadian hospitals

Green G.


In this study, total staff absenteeism (Lost Work Days - LWD) across three hospitals was compared alongside the average relative humidity of the indoor working environments. The study took place across three winters: 1973/4, 1974/5 and 1975/6. Two of the hospitals had no humidity control (B & C) and one hospital had a humidification system installed (A).

The survey was done across three winter periods (Oct-Apr). Data from winter 1973/74 is not shown in the table, as humidity differences were too small between humidified and non-humidified hospitals, and therefore no difference in absenteeism was detectable. Temperatures in all hospitals were identical, 24°C ±0.5°C.

The table presents the comparison for the two years with significant differences in humidity and LWD’s. The year-long average of LWD is 2.5%. This average workday loss was reduced in the humidified hospital to 1.87% (minus 0.63%) in the winter of 1974/5 and 1.56% (minus 0.94%) in 1975/6.

Absenteeism caused by respiratory illness accounted for roughly 60% of absenteeism, according to an inquiry of hospital staff by the author.

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by Walter Hugentobler

This three-year study showed a significant reduction in absenteeism during the six winter months from humidification of the working environment, although the achieved humidity levels (34.4 and 31.2%RH) were modest and below the ideal target of 40%RH.

The study indicates that humidification can reduce the anticipated total absenteeism rate of 2 to 3% by 0.5 to 1% in an adult workforce.

This is very significant in terms of health care costs as well as productivity, profitability and wage loss.

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