Measuring the fine particulate exposure levels of building occupants using localized sensors

Rising levels of Environmental Air Pollution (EAP) caused by wildfires and traffic emissions impact Indoor Air Quality (IAQ) by penetrating buildings through air conditioning intakes and door and window openings. Exposure to fine Particulate Matter (PM2.5) causes building occupant discomfort and significant health issues. Hence, it is vital to continuously monitor the PM2.5 exposure level and the general IAQ of buildings. This study uses Internet of Things (IoT) sensors to investigate the temporal and spatial correlations between indoor and outdoor PM2.5 concentrations in a university building in Sydney, Australia, over five months. Sensor measurements are used to determine the Indoor to Outdoor (I/O) ratio and Exceedance Index (E-index). The study timeline included impacts associated with Hazard Reduction Burning (HRB) and localized peak traffic flow. The findings reveal that the closest indoor area to the building entrance exceeded double the World Health Organization (WHO) PM2.5 recommended threshold for more than 80% of the study period. Results also confirm a negative correlation between the distance from ground level and indoor PM2.5 exposure. An hourly analysis shows that the PM2.5 concentrations in Winter increase overnight. During HRB in Winter, the I/O ratios increased by up to 200% on average during regular HVAC operating hours. Localized outdoor readings were also compared with the nearest regional air quality monitoring station (RAQMS). Those results indicate that the average PM2.5 for the local outdoor sensor was approximately 2.5 times higher than the nearest RAQMS, confirming that regional stations may not be reliable references for localized PM2.5 concentrations. •PM2.5 concentration increased overnight in winter.•A local outdoor sensor measured higher PM2.5 levels than the nearest meteorology station.•A negative correlation was observed between the distance from ground level and indoor PM2.5 exposure.•The HVAC system might be a potential route for PM2.5 penetration in extreme air pollution conditions.