Spatial variability of nitrogen dioxide and formaldehyde and residential exposure of children in the industrial area of Viadana, Northern Italy

Abstract

Chipboard production is a source of ambient air pollution. We assessed the spatial variability of outdoor pollutants and residential exposure of children living in proximity to the largest chipboard industry in Italy and evaluated the reliability of exposure estimates obtained from a number of available models. We obtained passive sampling data on NO₂ and formaldehyde collected by the Environmental Protection Agency of Lombardy region at 25 sites in the municipality of Viadana during 10 weeks (2017-2018) and compared NO₂ measurements with average weekly concentrations from continuous monitors. We compared interpolated NO₂ and formaldehyde surfaces with previous maps for 2010. We assessed the relationship between residential proximity to the industry and pollutant exposures assigned using these maps, as well as other available countrywide/continental models based on routine data on NO₂, PM₁₀, and PM_2.5. The correlation between NO₂ concentrations from continuous and passive sampling was high (Pearson's r = 0.89), although passive sampling underestimated NO₂ especially during winter. For both 2010 and 2017-2018, we observed higher NO₂ and formaldehyde concentrations in the south of Viadana, with hot-spots in proximity to the industry. PM₁₀ and PM_2.5 exposures were higher for children at < 1 km compared to the children living at > 3.5 km to the industry, whereas NO₂ exposure was higher at 1-1.7 km to the industry. Road and population densities were also higher close to the industry. Findings from a variety of exposure models suggest that children living in proximity to the chipboard industry in Viadana are more exposed to air pollution and that exposure gradients are relatively stable over time.

Keywords: Environmental monitoring; Exposure assessment; Land use regression; Ordinary kriging; Passive sampling; Wood industry.

Fig. 1

Weekly concentrations of NO₂ measured by continuous monitors and passive samplers during the cold (a) and warm seasons (b). Municipality of Viadana, 2017–2018. The solid line represents weekly average concentrations by the routine station; the solid and dashed thick lines represent the weekly average concentrations by the temporary station and the co-located passive sampler, respectively; the dotted line is the median concentration by the 25 passive samplers (coloured thin lines)

Fig. 2

Box and whiskers plot of recalibrated NO₂ concentrations at passive sampling locations in Viadana (2017–2018), by groups based on tertiles of distance to the industry

Fig. 3

Spatial distribution of annual NO₂ concentrations measured by passive samplers in 2010 (a) and 2017–2018 (b). Obtained using ordinary kriging. Colour coding is based on the quantiles of the distribution within each monitoring campaign. Black contour lines represent the 90th percentile. The white triangle represents the industry in Viadana. Blue triangles represent smaller wood factories. Cyan dots represent passive sampling sites

Fig. 4

Spatial distribution of annual formaldehyde concentrations measured by passive samplers in 2010 (a) and 2017–2018 (b). Obtained using ordinary kriging. Colour coding is based on the quantiles of the distribution within each monitoring campaign. Black contour lines represent the 90th percentile. The white triangle represents the industry in Viadana. Blue triangles represent smaller wood factories. Cyan dots represent passive sampling sites