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Air recirculation and sick building syndrome: a blinded crossover trial
J J Jaakkola1, P Tuomaala, O Seppänen
1Department of Public Health, University of Helsinki, Finland.
American Journal of Public Health
|March 1, 1994
Summary
Recirculated air in buildings does not cause sick building syndrome symptoms. Using 70% recirculated air with adequate outdoor air intake is safe for worker health and indoor air quality.
Area of Science:
- Environmental Health
- Building Science
- Occupational Health
Background:
- Sick Building Syndrome (SBS) is linked to poor indoor air quality.
- Mechanically ventilated buildings often use recirculated air, raising concerns about health effects.
Purpose of the Study:
- To investigate if recirculated air in buildings causes SBS symptoms.
- To assess the impact of recirculated air on perceived indoor air quality.
Main Methods:
- A blinded, four-period crossover trial in two identical buildings.
- Compared 70% recirculated air (index) vs. 0% (reference) over 1 work-week periods.
- 75 workers with prior symptoms reported daily on symptoms and perceptions.
Main Results:
- No significant differences in symptom scores between recirculated and fresh air phases.
- Unpleasant odor ratings were lower with recirculated air.
- Perceptions of dustiness and stuffiness did not differ significantly.
Conclusions:
- 70% recirculated air, with sufficient outdoor air, does not adversely affect worker health.
- Recirculated air can be used safely in mechanically ventilated buildings.
- Indoor air quality perceptions are not negatively impacted by moderate recirculation.