Low emission and clean air zones attract controversy whenever they are proposed, but there is growing evidence that they work in improving air quality. The Bradford zone was followed by a reduction of about 25% in GP visits for heart and breathing problems and survey data shows that the central London zone was followed by a reduction in the likelihood of a person taking sick leave.
Now analysis of health records has found emergency admissions to hospital reduced after the introduction of the T-charge and ultra-low emissions zone (Ulez) in central London.
Both schemes were designed to reduce air pollution inhaled by Londoners. Starting in 2017, the T-charge was an additional congestion charge for older, more polluting vehicles. During T-charge, many of the vehicles that drove in central London were upgraded in preparation for the introduction of the more comprehensive central London Ulez in 2019.
Dr Rosemary Chamberlain, who undertook the research at Imperial College London, said: “Given what we know about the link between air pollution and health, we wanted to understand if the introduction of the T-charge and Ulez also resulted in a reduction in people being admitted to hospital.”
The researchers looked at emergency admissions to hospital, excluding cases such as accidents, burns, drug overdose, poisoning or self-harm. For people living in the central London zone, admissions increased at 3% per year before the schemes started. After their launch there was decrease of 3% per year in emergency admissions, including an 8% reduction for heart problems and a 6% reduction for breathing problems.
The researchers then investigated whether the changes could have been due to other factors.
Chamberlain said: “We needed to make sure that we could separate the effect of the schemes from other trends, such as changes in healthcare seeking behaviour, overall trends in hospital admissions and other policies that improved air pollution. We did this by looking at other areas in the country that are similar to the central Ulez area.”
The reduction in the total emergency admissions and the decrease for heart problems remained robust when compared with other areas. The downward change for breathing problems was still present in the data, but this did not reach statistical significance.
Chamberlain said: “The inconclusive finding for respiratory outcomes may be partly because our analysis considered adults only. Children are particularly susceptible to the effects of air pollution on respiratory health, so an analysis of childhood respiratory outcomes may show a more conclusive result.”
The central London Ulez was launched just one year before the Covid pandemic. Although nitrogen dioxide from traffic had been reduced by about 44% on roads in central London before lockdowns began, the researchers did not have sufficient health data to distinguish between the separate effects of Ulez and T-charge.
Dr Daniela Fecht, who led the study, said: “We controlled for other factors and trends in our study design so we can conclude that reductions in hospital admissions are directly linked to the emission reduction initiatives in central London.
“Other factors such as more walking and cycling or a reduction in traffic noise may also be contributing but we are fairly certain that these improvements in health are due to the reductions in air pollution. Our results provide clear evidence that clean air zones and low emission zones can bring public health benefits.”
