The exposure assessment period to air pollutants which affects lung function: analysis of recent studies and an explanatory model

Empirical studies have shown that exposure to ambient air pollution can impair lung function (LF). However, knowledge regarding the length of exposure necessary to detect a measurable effect of a specific air pollutant on LF remains limited. By reviewing recent studies, this paper aims to identify the exposure period necessary for detecting a significant effect of specific air pollutants on LF. We searched the PubMed database and selected studies according to pre-defined inclusion-exclusion criteria. Studies were analyzed to identify the preferred exposure period leading to a significant decrease in LF. A total of 32 studies were included in our analysis. The analysis shows that out of the five air pollutants considered (NOX, PM2.5, PM10, SO2, O3), an exposure assessment period of at least 2 years was associated with a significant effect on lung function for NOX and PM2.5. No preferred exposure assessment period was found for the other pollutants evaluated. The findings suggest that for NOX and PM2.5, an assessment period of at least 2 years is recommended for air pollution studies to find a significant effect on lung function. This may be attributable to the pathophysiology and characteristic deposition of these pollutants along the airways.