Quantifying the Transmission of Outdoor Pollutants into the Indoor Environment and Vice Versa—Review of Influencing Factors, Methods, Challenges and Future Direction

Abstract

Epidemiological studies have established a strong relationship between poor air quality and deteriorating human health, demanding urgent remedial measures. Specifically, indoor pollution is more critical, and outdoor pollutants significantly contribute towards indoor pollution, its strength depending on various parameters, including ventilation strategy, meteorological conditions, building design, outdoor sources, etc. This report analyses the various factors reported influencing the transmission of pollutants between the two environments. The report critically reviews various studies investigating the inter-environment variability and transmission, providing an overview of various factors and their impacts and covering both experimental and modelling studies. The review suggests that while many studies have helped to quantify the long-term personal exposure to pollutants, they have not paid special attention to the mechanism of the transmission of pollutants from the outdoor to the indoor environment and vice versa. The findings demonstrate that the proper indexing of various mechanisms and their relative strength is necessary before an effective intervention strategy can be applied in the built environment to counter the effect of pollution.