Comparison of diffusion tube\u2013measured nitrogen dioxide concentrations at child and adult breathing heights: who are we monitoring for?

Alex Rowell,Michael E Deary,Michael E Terry

doi:10.1007/s11869-020-00909-4

Alex Rowell, Michael E Deary + Show 1 more

Open Access

https://doi.org/10.1007/s11869-020-00909-4

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Abstract

Many towns and cities use passive samplers (diffusion tubes) to monitor nitrogen dioxide (NO2) concentration. However, literature studies have shown large horizontal and vertical concentration gradients for diffusion tubes placed over short distances, raising concerns over the representativeness of monitoring locations. This study examines variations in NO2 concentrations with height at two roadside locations along a busy urban road in Newcastle upon Tyne (UK) over an 8-month period. NO2 concentrations were passively monitored at building facades (approximately 7.0 m from the roadside) at heights of 0.7 m, 1.7 m and 2.7 m to replicate child breathing height in prams and buggies, adult breathing height and the Newcastle City Council sampling height (for 2017), respectively. Paired t tests indicated that NO2 concentrations were significantly lower at 2.7 m (4.7% lower, n = 16, p = 0.001) and 1.7 m (7.1% lower, n = 14, p = 0.007) compared with those at 0.7 m. There was no statistically significant difference between NO2 concentrations measured at 2.7 m and 1.7 m, indicating that UK local authority practice of placing diffusion tubes at higher than adult breathing height does not result in underreporting of NO2 concentrations for regulatory purposes. The results have clear public health implications as they provide evidence that young children, in an urban setting and close to busy roadways, may be exposed to higher NO2 concentrations compared with adults in the same location. We have shown that such differences might not be adequately reflected in the monitoring data from municipal authorities.

Highlights

Elevated traffic-derived nitrogen dioxide (NO2) concentrations in urban areas have been linked to increased incidences of both mortality and disease (Atkinson et al 2018; Committee on the Medical Effects of Air Pollutants 2018; Mills et al 2016; World Health Organization (WHO) 2006)
The general trends for monthly NO2 concentrations shown in Fig. 1 are typical of the annual European pattern of NO2 concentrations, with the highest concentrations observed in winter months due to meteorological conditions such as ground-level temperature inversions and increased use of domestic heating (Hazenkampvon Arx et al 2004)
Paired t test results showed that NO2 concentrations at child breathing heights were on average 4.71% and 7.12% lower at 2.7 m and 1.7 m respectively compared with that at 0.7 m

Summary

Introduction

Elevated traffic-derived nitrogen dioxide (NO2) concentrations in urban areas have been linked to increased incidences of both mortality and disease (Atkinson et al 2018; Committee on the Medical Effects of Air Pollutants 2018; Mills et al 2016; WHO 2006). Adverse health effects of NO2 on children (Esposito et al 2014; Favarato et al 2014; Gaffin et al 2018), given that many schools are located in areas that breach air quality guidelines for NO2 (Guerriero et al 2016; Salonen et al 2019). There is evidence that NO2 is associated with health effects at concentrations that are well below the guideline values, even as low as 5 μg m−3 (Committee on the Medical Effects of Air Pollutants 2018). At locations immediately adjacent to roads, 80% of the total NOx emissions are contributed from road sources

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