London LEZ ‘fails to improve’ respiratory health

Researchers have produced a paper which reasons that the London LEZ has had limited impacts on health

The London low emission zone (LEZ) has not significantly improved air quality within the city, or the respiratory health of the resident population in its first three years of operation.

The London low emission zone has not been as beneficial to children's health as expected, a research study has found

The London low emission zone has not been as beneficial to children’s health as expected, a research study has found

The conclusion comes in a research article published last month in online PLOS journal by a group of academics. They looked at the adverse effects of traffic-related air pollution on children’s respiratory health.

The researchers, who come from a range of organisations including London’s King’s College and Queen Mary’s University, carried out a study looking at asssociations between traffic-related air pollutants and respiratory/allergic symptoms amongst 8—9 year-old schoolchildren living within the London Low Emission Zone (LEZ).

And, the study says that the work confirms a link between traffic-related air pollutant exposures and symptoms of current rhinitis.


Information on respiratory/allergic symptoms was obtained using a parent-completed questionnaire and linked to modelled annual air pollutant concentrations based on the residential address of each child, using a multivariable mixed effects logistic regression analysis.

The abstract says that the results “highlight the need for more robust measures to reduce traffic emissions.”
And, the academics note: “This study shows that traffic-related air pollutants have adverse effects on respiratory/allergic symptoms in schoolchildren in London and that London’s LEZ has had no beneficial effect on these symptoms, up to three years after its implementation. As the majority of children in this study are exposed to levels of air pollutants higher than those recommended by the WHO this is an important finding.”

The point is highlighted that policy makers should note that the LEZ, “which was designed to reduce traffic-related emissions in London, has not actually done so up to this point.”

‘Not targeted’

And the researchers say that “In part, for PM10 and PM2.5 this may reflect the fact that traffic sources (excluding cars and non-exhaust sources, not targeted by the LEZ) only contribute 3.0 and 2.3%, respectively, of the measured concentrations at urban background sites (S3 Text). Hence, any change in PM is likely to have been small and very difficult to detect amongst all of the other ‘noise’ caused by the weather, economy etc.”

The study adds: “In contrast, had the LEZ performed as predicted one would have expected a measureable decreases in NOx, as a significant proportion of both the roadside (51.8%) and background concentrations (26.5%) was due to vehicle types targeted by the scheme. This was not seen, largely due to the failure of Euro III and IV diesel engines to produce the predicted NOx emissions under real-world driving conditions. As the subsequent phases of the LEZ target a larger proportion of the vehicle fleet in London, with stricter emissions limits, it will be important to investigate whether improvements do occur in the subsequent years.”

Source: Effects of Air Pollution and the Introduction of the London Low Emission Zone on the Prevalence of Respiratory and Allergic Symptoms in Schoolchildren in East London: A Sequential Cross-Sectional Study. Abstract available at:


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