Traffic-related pollution and asthma prevalence in children. Quantification of associations with nitrogen dioxide

Abstract

Ambient nitrogen dioxide is a widely available measure of traffic-related air pollution and is inconsistently associated with the prevalence of asthma symptoms in children. The use of this relationship to evaluate the health impact of policies affecting traffic management and traffic emissions is limited by the lack of a concentration-response function based on systematic review and meta-analysis of relevant studies. Using systematic methods, we identified papers containing quantitative estimates for nitrogen dioxide and the 12 month period prevalence of asthma symptoms in children in which the exposure contrast was within-community and dominated by traffic pollution. One estimate was selected from each study according to an a priori algorithm. Odds ratios were standardised to 10 μg/m3 and summary estimates were obtained using random- and fixed-effects estimates. Eighteen studies were identified. Concentrations of nitrogen dioxide were estimated for the home address (12) and/or school (8) using a range of methods; land use regression (6), study monitors (6), dispersion modelling (4) and interpolation (2). Fourteen studies showed positive associations but only two associations were statistically significant at the 5 % level. There was moderate heterogeneity (I2 = 32.8 %) and the random-effects estimate for the odds ratio was 1.06 (95 % CI 1.00 to 1.11). There was no evidence of small study bias. Individual studies tended to have only weak positive associations between nitrogen dioxide and asthma prevalence but the summary estimate bordered on statistical significance at the 5 % level. Although small, the potential impact on asthma prevalence could be considerable because of the high level of baseline prevalence in many cities. Whether the association is causal or indicates the effects of a correlated pollutant or other confounders, the estimate obtained by the meta-analysis would be appropriate for estimating impacts of traffic pollution on asthma prevalence.Electronic supplementary materialThe online version of this article (doi:10.1007/s11869-014-0265-8) contains supplementary material, which is available to authorized users.

Traffic-Related Air Pollution and Childhood Asthma: Recent Advances and Remaining Gaps in the Exposure Assessment Methods

“…The prominent focus on NO 2 in the literature is probably related to the wide availability of this pollutant measure, the ease and relatively low cost to measure it and its relative specificity to road traffic [30]. The focus on NO 2 in air quality guidelines, plans and mitigation strategies in the EU, and beyond, is perhaps reinforcing the study of this pollutant.…”

“…We conducted a hand search in the reference lists of all the included studies and of previous relevant reviews we identified [15,17,23,24,25,26,27,28,29,30]. We contacted authors of unpublished studies (abstracts only) and the authors of the most recurrent studies to ensure the inclusion of all relevant published material on the topic and this resulted in the inclusion of two additional studies [31,32].…”

Meta-analysis of the IL-10 promoter polymorphisms and pediatric asthma susceptibility

“…The past 20 years have seen a significant increase in the prevalence of asthma in children (Tang et al, 2015). The pathogenesis of asthma is related to multiple risk factors including environmental factors such as vehicular pollution, and genetic factors such as polymorphisms in the interleukin (IL)-4 and ORMDL3 genes (Favarato et al, 2014;Tang et al, 2014;Zhai et al, 2015).…”

Distributional cost effectiveness analysis of West Yorkshire low emission zone policies

“…Each LSOA within an middle layer super output area was assigned the same baseline rate of events. Dose response functions from meta‐analyses and studies recommended by Committee on the Medical Effects of Air Pollutants (COEMAP) link change in pollution exposure in each area to change in incidence of pollution‐linked disease (Cesaroni et al, ; Colbourn et al, ; Department of Health Medical Directorate Respiratory Team, ; Favarato et al, ; Hoek et al, ; Mangham, Petrou, Doyle, Draper, & Marlow, ; Pedersen et al, ; Sapkota, Chelikowsky, Nachman, Cohen, & Ritz, ; Schikowski et al, ; World Health Organisation, ). These determine the absolute number of cases averted for each LSOA, according to the size and age structure of the population in each local authority reported in the 2011 Office for National Statistics census .…”