Occupational Exposure to Biological Agents in a Typical Restaurant Setting: Is a Photocatalytic Air Purifier Helpful?

According to many national legislations, biological agents represent an occupational hazard that must be managed in order to ensure safety at workplace. Bioaerosols have been associated to many pathological conditions but, despite many efforts, precise threshold limit values (TLV) are still undefined. We planned and conducted an environmental study concerning a typical restaurant that aimed to evaluate: (1) the occupational exposure to bacterial and fungal bioaerosol; (2) the efficacy of a photocatalytic air purifier device in mitigating such exposure. This observational study evaluated two dining rooms (Area 1 and Area 2) of a restaurant which can be considered typical during two consecutive weeks. Based on a national protocol, we monitored total bacterial and mycotic loads searching for two typologies of bacteria, psychrophilic bacteria (environmental contamination) along with mesophilic bacteria (human or animal origin source), and two types of fungi, mold and yeast. Baseline total bacterial load was 346.8 CFU/m(3) for Area 1 and 412.9 CFU/m(3) for Area 2. When the sanitizing device was operative, the total bacterial load decreased to 202.7 CFU/m(3) (-41.50%-p value: <0.01) for Area 1 and to 342.2 CFU/m(3) (-1-17.10%-p value: 0.06) for Area 2. Considering the fungal load, the mean baseline value was 189.7 CFU/m(3) for Area 1 and 141.1 CFU/m(3) for Area 2. When the device was kept on, the total fungal load was 108.0 CFU/m(3) (-4-43.10%-p value: 0.055) for Area 1 and 205.0 CFU/m(3) (+45.30%-p value: 0.268) for Area 2. Our findings supported the conclusion that, concerning the occupational risk derived from biological agents, a typical restaurant should be considered relatively safe. In order to mitigate or limit any possible increase of such risk, a photocatalytic device may be helpful, but not against the pollution caused by mold or yeasts. Our research also reaffirmed the need of further research assessing the kind of relationship between diseases and exposure levels, before considering the need of setting precise threshold limit values.