Indoor and outdoor air quality relationships modelling

Particulate matter (PM) related ambient pollution has emerged as one of the most significant environmental and human health issues during the last decades. Thus, ambient PM concentration levels have been widely investigated through several studies. On the contrary, investigation of indoor microenvironments, where people spend most of their time, air quality conditions is rather limited.

In this study, indoor and outdoor air quality conditions were analyzed across different areas with distinct characteristics towards a better understanding of the complex relationships between indoor and outdoor air quality levels and the mechanisms governing infiltration factors. Simultaneous PM_2.5 concentration measurements were conducted, using particle sensors, providing useful information for the identification of Indoor Air Quality (IAQ) variation due to sharp changes in outdoor conditions.

The dynamics of PM infiltration factor, the fraction of ambient particles that infiltrate indoors either by mechanical or natural ventilation, that provoked degraded indoor air quality conditions, have also been evaluated. Moreover, an algorithm is developed, based on regression models, to estimate the infiltration factor, through IO (indoor/outdoor) ratios. The estimated infiltration factor would facilitate the quantification of the fraction of the indoor generated particles to the total indoor concentrations.

The integration of several parameters such us as building characteristics, ventilation systems, air exchange rates, indoor activities and meteorological conditions will elucidate the mechanisms that affect relationship between outdoor and indoor measurements. These findings could provide substantial knowledge to the relationship between infiltration factor and IAQ that is crucial for promoting healthier indoor environments. The study mainly focuses on time periods where outdoor PM_2.5 concentrations are dominant, to model more accurately the infiltration factor and the corresponding IAQ at each measurement site. Overall, the synergy of in situ, outdoor and indoor air quality, measurements and  physical modelling will enhance the knowledge on IAQ and could engage the adoption of better IAQ systems and practices.