Abstract
Bioassay, which detects biohazardous property of environmental contaminants, is still being an unexplored field of air quality monitoring. This study aims to develop a simple testing system of toxicity of the indoor particulate matter by detecting bioluminescence reduction of marine bacterium Vibrio fischeri. Suspended particulate matter in indoor and outdoor air was collected on a quartz fiber filter at a flow rate of 23.5 L/min by a low volume air sampler for 7-day duration, at the terrace and living room of an apartment house in Kanagawa, Japan. Collected materials were extracted with sterilized distilled water by mild shaking. After filtration with 0.45 μm pore size filter, the extracts were subsequently mixed with a bacterium solution in a well of 24-well plate and time courses of bioluminescence intensity were measured by a luminometer. Meanwhile, House dust samples were collected from filter bags of household cleaners of 4 houses in metropolitan area. House dust samples were size-fractionated by stainless steel sieves and then served for bioassay as well. As a result, the water extracts of indoor and outdoor aerosol samples significantly reduced the bioluminescence of Vibrio fischeri and the inhibition per sampling volume increased with increasing of TSP (Total Suspended Particles) concentrations. The inhibition per unit mass of the indoor aerosols became greater than that of outdoor aerosols, when increasing in air change rate. On the other hand, the water extracts of house dust also showed the inhibition of bioluminescence especially in fine mode. The inhibition tended to correlate with nitrate and sulfate concentrations in the extracts. This study showed possible application of bioassay to the monitoring of indoor particle contamination.
