The Oxford Transport Strategy: impact of a traffic intervention on PEF and wheeze among children

Abstract

The Oxford Transport Strategy (OTS) was a major traffic intervention implemented in June 1999. It involved a wide range of permanent changes focused primarily on the city centre of Oxford (England). We aimed to assess the impact of OTS on peak expiratory flow (PEF) and respiratory symptoms among city schoolchildren. Between 1998 and 2000, 1389 children aged 6–10 years were visited 2–3 times a year for 5-day periods. On each day of each visit, we measured their PEF and enquired about respiratory symptoms including wheeze (n = 19260 child-days of data). Exposure to traffic pre and post-OTS was estimated by the change in modelled traffic on the street nearest the home. Pre-OTS traffic levels were relatively low compared to other major cities, but post-OTS changes in children's exposure varied considerably; from a drop of 11184 to an increase of 9240 vehicles/24hrs. Adjusted regression analyses showed a statistically significant improvement in PEF (beta = 5.71 L·min–1, 95% CI (3.28, 8.18)) and wheeze (OR = 0.80, 95% CI (0.69, 0.92)) post-OTS. The impact of OTS on PEF was greater among children living near roads where traffic decreased compared to those living where there had been an increase. This association was only found among children currently receiving treatment for asthma and those in socio-economic classes III–V. These results suggest that even in cities with relatively low traffic levels interventions can result in improvements in the respiratory health of children. These benefits may be especially pertinent to children with pre-existing respiratory problems and those from less affluent socio-economic backgrounds.