The composition, source apportionment and health risk assessment of fine particulate matter in naturally ventilated school environment

Abstract

Indoor Air Quality (IAQ) becomes a growing concern of public health and environmental issues due to possible health implications and various respiratory illnesses. Hence, this study aimed to determine the composition of inorganic PM2.5 and emphasized the source apportionment of PM2.5 using multivariate statistical analysis. This study also assessed the potential health risk of carcinogenic and non-carcinogenic towards school children since they spend 70% of their time in school. The samples were collected on quartz microfiber filter using a portable low volume air sampler (LVS) at a flow rate of 5 L/min for daily 8 h basis from May to October 2016. The total 180 samples were collected simultaneously for indoor and outdoor at three different primary schools in Selangor; namely Taman Muda Primary School (urban), Lubok Kelubi Primary School (sub-urban) and Rinching Primary School (industrial). The composition of PM2.5 determined were water soluble inorganic ions (WSII), trace metals and black carbon. Water soluble ionic species (Cl- , NO3 - , SO4 2- , Na+ , NH4 + , K+ , Mg2+, Ca2+) were analysed using ion chromatography (IC) and trace metals concentrations (Al, Fe, Zn, Cr, Cu, Mn, Pb, Ni, As, Co and Cd) were using inductively coupled plasma-mass spectrometry (ICP MS), respectively. The results showed that the highest average of PM2.5 concentration in indoor classroom recorded in the school located in industrial area (23.5 μg/m3 ) followed by urban (18.6 μg/m3 ) and semi-urban (9.58 μg/m3 ). The indoor-to-outdoor (I/O) ratio values for PM2.5 concentrations and major elements at all sampling sites were greater than one, indicating the presence of indoor sources. Most WSII and trace metals were found significantly higher indoors (p<0.05) compared to outdoors. The concentrations of water soluble ionic species (WSIS) measured in PM2.5 collected in indoor are shown in descending order : NH4 + > SO4 2- > NO3 - > Ca2+ > Na+ > K+ > Cl- > Mg2+ . The trend for chemical mass closure (CMC) analysis were as follows; secondary inorganic aerosol (SIA) > sea salt (SS) > mineral matter (MIN) > trace elements (TE). The potential health risks for trace elements in PM2.5, via inhalation exposure to the children in the classroom, show that the total hazard quotient (HQ) value was lower than the acceptable limits (1.0). The total excess life carcinogenic risk (ELCR) value for all three stations shows that the value as found to be slightly higher than the acceptable level for Cr(vi), (1.0×E-06). The results from this study conclude that highest PM2.5 exposure and carcinogenic risk of school children in indoor is at Rinching Primary School (industrial) followed by Taman Muda Primary School (urban) and Lubok Kelubi Primary School (sub urban). Thus, mitigation on indoor air pollutant significantly needs to be implemented in order to reduce indoor air pollution.