NOx levels have been reduced by 20%. Photo: © Lorna Roberts /

Low and ultra-low emission zones proven to be effective

In spring 2019, London implemented an ultra-low emission zone (uLEZ) to tackle road transport air pollution. A recent study quantified the effects of this policy on London air quality, using models and monitoring stations and adjusting for meteorological variables.

The results showed the uLEZ intervention was successful in reducing NO, NO2, and NOx concentrations not just within the zone of implementation but also throughout the wider low emission zone (LEZ) and Greater London area. NOx levels were reduced by 20% in the uLEZ, 17% in the LEZ and 15% in the Greater London area respectively.

For NO2 the effect was largest in the Greater London area (13%). A health impact analysis was conducted to estimate the effect of a hypothetical LEZ on mortality and morbidity in Malmö, Sweden. The scenario assumed that all vehicles on municipal roads would meet Euro 5 or lower emission standards with Euro 6 equivalents.

This would decrease NO2 concentrations by 13.4%, preventing an estimated 9–26 deaths in Malmö each year. It was also estimated that 12 respiratory disease hospitalizations, 8 childhood asthma cases and 9 cases of hypertensive disorders of pregnancy would be avoided annually. These results suggest that LEZs can effectively improve air quality and improve public health.

doi: 10.1016/j.apr.2022.101514.


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