Lung inflammation from daily exposure to airborne particulate matter in a trade school

Workers are exposed daily to various airborne chemical agents, however, associations between daily exposures to particulate matter and lung inflammation in occupational settings have been little explored.

To estimate the association between daily occupational exposure to respirable (PM4 and PM2.5), ultrafine particles, their oxidative potential, and fractional exhaled nitric oxide within apprentices in a school of construction trades.

We used a repeated measures design over 5 consecutive days in 56 apprentices from 3 construction trade sectors (bricklaying, welding, and carpentry). Fractional exhaled nitric oxide was measured each day post-work. Personal and work area daily PM4 were collected using filter cassettes while work area PM2.5 and ultrafine particles concentrations were measured with direct-reading instruments. The ascorbate assay was used to estimate personal and work area PM4 oxidative potential (OPaa) and burden (OBaa). Associations between fractional exhaled nitric oxide and exposure metrics were estimated using mixed effect linear models.

The post-work shift fractional exhaled nitric oxide (n = 210) ranged from 5.0 to 91.5 ppb. Median personal PM4 and work area PM4 and PM2.5 concentrations were, respectively, 361 µg/m3 (interquartile range: 437 µg/m3), 260 µg/m3 (interquartile range: 323 µg/m3), and 104 µg/m3 (interquartile range: 155 µg/m3). Estimates of association with fractional exhaled nitric oxide were positive for all exposure metrics although highly variable for ultrafine particles. Estimates of association with fractional exhaled nitric oxide for personal PM4 OPaa and OBaa were, respectively, 0.88 ppb (95% CI: -0.54, 2.30) and 0.20 ppb (95% CI: -0.07, 0.47). Fractional exhaled nitric oxide increased by 2.22 ppb (95% CI: 0.24 to 4.20) and 0.45 ppb (95% CI: -0.11 to 1.01) per interquartile range increase in daily work area PM4 OPaa and OBaa, respectively. Estimates of association with fractional exhaled nitric oxide were 0.99 ppb (IC95%: -0.70 to 2.69) and 0.85 ppb (95%CI: 0.003 to 1.68) per interquartile range increase in daily work area concentration of PM4 and PM2.5, respectively.

Results suggest that repeated daily exposure to oxidative particulate matter may be associated with an increase in fractional exhaled nitric oxide and, therefore, may induce airway inflammation in apprentices early in the labor market. Further investigation is warranted to clarify whether low repeated fractional exhaled nitric oxide increments may lead to long-term effects in workers.