RELATIONSHIPS BETWEEN VENTILATION AND INDOOR AIR-QUALITY - A REVIEW

Adjustment of ventilation rates in buildings is widely practised, both to provide good air quality on a proactive basis and to mitigate air quality problems associated with occupant complaints. However, both cr oss-sectional and experimental epidemiological studies have reported m ixed results and have for the most part failed to establish definitive relationships between ventilation rates and symptom prevalence or dis satisfaction with air quality. The difficulties involved in establishi ng such relationships may be due to a variety of confounding factors w hich include limitations in study design and interaction effects; diff iculties in controlling ventilation rates in experimental studies; ina dequate mixing of supply air in occupied spaces; high source strengths for some contaminants; dynamic interactions between sources and venti lation rates that result in increased contaminant emissions; contamina nt dose-response sensory effects which are log-linear; potential conta minant generation within ventilation systems themselves; and multifact orial genesis of sick building symptoms. There is limited evidence to suggest that ventilation rate increases up to 10 L/s . person may be e ffective in reducing symptom prevalence and occupant dissatisfaction w ith air quality and that higher ventilation rates are not effective. B ecause of complex relationships between ventilation rates, contaminant levels, and building-related health complaints/dissatisfaction with a ir quality, the use of ventilation as a mitigation measure for air qua lity problems should be tempered with an understanding of factors whic h may limit its effectiveness.