Children's respiratory health and oxidative potential of PM2.5: the PIAMA birth cohort study

What this paper adds Oxidative potential (OP), which measures the inherent capacity of particulate matter (PM) to oxidise target molecules, has been proposed as a biologically more relevant exposure metric than PM with an aerodynamic diameter of less than 2.5 [micro]m (PM_2.5 ).

This is the first study on the associations between long-term exposure to two measures of OP (assessed by dithiothreitol assay (OP^DTT ) and spin resonance (OP^ESR )) of PM_2.5 and children's respiratory health.

Exposure to OP^DTT , but not OP^ESR and PM_2.5 mass, was associated with increased risks of asthma and rhinitis until age 14 years, and decreased lung function at age 12 years.

Associations of OP^DTT with asthma symptoms and rhinitis were largely independent of exposure to other air pollutants, including NO₂ , PM_2.5 mass and PM_2.5 constituents.

Our study suggests that OP^DTT could be a health-relevant metric.

Introduction

Numerous epidemiological studies have established associations between exposure to ambient air pollution and respiratory health. 1 2 Various exposure metrics have been used to investigate the effect of air pollution on human health, such as particulate matter (PM) with an aerodynamic diameter of less than 2.5 [micro]m (PM_2.5 ) and 10 [micro]m (PM₁₀ ); traffic markers (elemental carbon (EC); nitrogen dioxide (NO₂ )); and less frequently, different PM constituents (iron, copper, nickel, zinc, vanadium, sulfur, potassium, silicon). 3 4 However, PM toxicity is likely to be reflected by the sum of multiple toxic components. Since toxicological studies have documented the ability of inhaled PM to cause oxidative stress and inflammation in the airways, 5-8 oxidative potential (OP), which measures the inherent capacity of PM to oxidise target molecules, has been proposed as a biologically more relevant exposure metric. 9

Currently, there is limited epidemiological evidence on the relationship between OP and health; consequently, it is not clear whether OP has more consistent associations with health than other PM characteristics. 10 Recently, a few studies have assessed the acute health effects of OP, especially on respiratory health end points. The findings, so far, did not consistently indicate that OP is a better predictor of acute health effects than other air pollution metrics. 11-16 High correlation between temporal patterns...