London's low emission zone shows little impact on children's respiratory health

Large-scale Low Emission Zones (LEZs) can deliver improvements in urban air quality and these can be linked to changes in childhood respiratory health. However, more ambitious schemes are required to meet legislative limits and deliver improvements to respiratory health, according to a study in the Lancet Public Health journal.

The study looked into the impact of London’s LEZ and found that while it has improved air quality it has not been enough to benefit children’s lung health.

The observational study was conducted with more than 2,000 primary school children living in areas of high pollution within the low emission zone. The research tested the lung capacity of eight-to nine year old children between 2009 and 2014. It began just after LEZ charges began and continued after the rules were tightened in 2012. 

LEZs are in place in 200 cities across Europe but only reductions in nitrogen dioxide were identified; as the percentage of children living at addresses exceeding the EU limit value for annual NO2 (40 μg/m3) fell from 99% in 2009 to 34% in 2013. However, little progress was found in the reduction of ultrafine particles (PM2.5) or particulate matter (PM10) over the study period, which is a health concern due to their ability to reach deep inside the lung. 

Within London's LEZ, a smaller lung volume in children was associated with higher annual air pollutant exposures. The study found that despite small improvements in air quality there was no evidence of a reduction in the proportion of children with small lungs over the five years since the zone was implemented.

Author of the report Professor Chris Griffiths from Queen Mary University of London said: ‘Some improvements in air quality have been made despite the diesel vehicles emitting higher levels of pollutants in the real world than in tests. 

‘Even so, many areas of inner and outer London are still breaching EU air pollution standards and are unlikely to meet them without a substantial tightening of current emission controls.’

Griffiths said: ‘Although changes of this magnitude are unlikely to cause problems in healthy children, we urgently need to know whether these lung deficits will impact lung function and health in later life.

‘Until longer-term impacts are known, doctors should consider advising parents of children with clinically significant lung disease to avoid living in highly polluted areas, or to adopt personal mitigation measures to limit their exposure. More research is needed to identify factors that lead to increased susceptibility or protection.’

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