Emergency hospital admissions fell after the introduction of London's T-charge and ultra-low emissions zone (Ulez), a new study suggests. Scientists from Imperial College London analysed health records before and after the implementation of these air pollution reduction measures.
Evidence of Health Benefits
Low emission and clean air zones often spark controversy when proposed, but growing evidence shows they improve air quality. For example, the Bradford zone was followed by a roughly 25% reduction in GP visits for heart and breathing problems. Survey data also indicates that central London's zone reduced the likelihood of people taking sick leave.
The new study examined emergency admissions to hospital, excluding cases such as accidents, burns, drug overdoses, poisoning, or self-harm. For residents of central London, admissions were increasing at 3% per year before the schemes began. After their launch, there was a 3% annual decrease in emergency admissions, including an 8% reduction for heart problems and a 6% reduction for breathing issues.
Methodology and Findings
The T-charge, introduced in 2017, was an additional congestion charge for older, more polluting vehicles. Many vehicles were upgraded in preparation for the more comprehensive central London Ulez in 2019. Dr Rosemary Chamberlain, who led 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 controlled for other factors, such as changes in healthcare-seeking behaviour, overall trends in hospital admissions, and other air pollution policies. They compared central London with similar areas across the country. The reduction in total emergency admissions and heart problems remained robust when compared with other areas. However, the decrease for breathing problems did not reach statistical significance.
Potential Explanations
Chamberlain noted: '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 launched just one year before the Covid-19 pandemic. Although nitrogen dioxide from traffic had been reduced by about 44% on central London roads before lockdowns began, the researchers lacked sufficient health data to distinguish between the separate effects of Ulez and the T-charge.
Public Health Implications
Dr Daniela Fecht, who led the study, stated: '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.'
