Physical characterization of particulate matter and ambient meteorological parameters at different indoor–outdoor locations in Singapore

The paper reviews the exposure to fine and coarse particles in different indoor and outdoor locations. The methodology involves measuring the particulate matter at different indoor and outdoor locations. The locations included a major expressway (high traffic volume), a minor road, and naturally and mechanically ventilated indoor spaces. It was observed that significant concentrations of fine particles were found at the expressway as compared to the normal road and naturally ventilated space. However, larger size particles were found to be higher in number density (count per litre) and mass concentration at the minor road and naturally ventilated space at close proximity to the minor road. In the mechanically ventilated space the particles above 1 μm size were negligible both in count and mass. A linear relation was established between the particle mass (PM10) and particle count (r2=0.5564r2=0.5564, n=60n=60). Denser particulate matter was found at naturally ventilated indoor spaces in the evenings. Indoor–outdoor ratio (I/O) for the naturally ventilated space is observed to be closer to unity as in the case of mechanically ventilated space with 0.46. A higher I/O ratio is observed in the evening as compared to morning for the naturally ventilated space. Better correlation was observed between fine and coarse mode particles at the expressway as compared to the minor road.