Relationships between air-conditioning, airborne microorganisms and health

Concurrently with the increase of air-conditioning, potentially severe or f requent new disease have emerged, giving rise to social and economical cons equences. The first part of this work is a state of the art review of the r elationships between air-conditioning airborne microorganisms and health, t hrough a technical, metrological and medical approach. the second part pres ents four studies performed in this field. Two of them deal with the relati onship between airborne microorganisms and technical features of air-condit ioning. measurements performed on actual sites demonstrated the benefit of using high efficiency filters and low risk components in air-conditioning s ystems. The third study was aimed to look for a relationship between airbor ne microorganisms and sick building syndrome symptoms. Statistical analyses of individual data revealed significant associations between airborne bact eria or fungi and symptoms. These results may be the first step in determin ing a dose-response relationship, in order to define threshold limit values in this field. In the fourth study, the contribution of particle counting in assessing exposure to airborne microorganisms was explored by monitoring simultaneous variations of microbial and particle concentrations. The resu lts showed that associating particle counting may allow to detect microbial variations instantaneously, and therefore improve the assessment of exposu re to airborne microorganisms.