The London Congestion Charge Scheme may have had a "modest benefit" on levels of air pollution and life expectancy in the capital, finds
research published ahead of print in Occupational and Environmental Medicine.
Extending it more widely and directly tackling vehicle
emissions may see greater benefits for public health, say the authors.
The Mayor of London introduced the vehicle levy in
designated areas five years ago this month, in a bid to ease traffic in central
London during working hours. The Congestion Charge Zone originally covered an
area of 21 km2, and a resident population of 200,000 people. It was
subsequently extended west to a much larger area last year.
The researchers focused on the original zone, and assessed
the impacts of air pollution on health within the zone and across London as a
They used models of annual levels of air pollution based on
measurements of changes in traffic flow across London.
They focused on nitrogen dioxide (NO2) and particulate
matter and the expected increase in life expectancy from reduced exposure to
The results showed that there was little change in pollutant
levels in London as a whole. But there were more substantial falls in the
Levels of NO2 fell the most. There were smaller falls in
particulate matter levels, which the authors ascribe to the comparatively large
amount that comes from outside the capital and the fact that sources other than
vehicles contribute to this form of pollution.
But the changes in both pollutants were greatest in the most
deprived areas of London.
The scheme has resulted in 1888 extra years of life gained
across the overall population of Greater London (roughly 7.2 million people)
and 683 years of life gained across the population in the congestion charging
zone wards (approximately 370,000 people).
On a per population basis, the number of life years gained
was therefore greater in the congestion charging zone, say the authors.
The Congestion Charge did not set out specifically to
improve health, and it covered a comparatively small part of inner London, say
the authors. But they conclude: "Policies affecting a larger geographical area
and residential population, and which directly aim to reduce vehicle emissions,
are likely to have larger public health impacts."
Traffic monitoring data published by Transport for
London suggest that there has been a 26% fall in the number of cars and a 7%
fall in heavy goods vehicles within the charging zones since the introduction
of the Scheme.