Executive Summary and Key results
UK100 commissioned Kings College London (King’s) to produce a health and economic impact assessment associated with current and future pollution levels in Birmingham City. In this study, King’s combined the relationships between Defra’s Air Quality modelling concentrations and health outcomes for each parliamentary constituency in Birmingham. King’s has previously carried out similar mortality burden calculations for London and Greater Manchester but to our knowledge this is the first time that the new burden recommendations that include a combined PM2.5 and NO2 approach have been applied in practice in a large city area. The calculations relate to deaths or loss of life expectancy from all causes rather than separately for specific causes or for cases of specific illnesses.
Mortality impact (long –term exposure)
The population in Birmingham would gain around 440,000 life-years over a lifetime to 2134 if air pollution concentrations improved as projected from 2011 to 2030, compared with remaining at 2011 concentrations. The average life expectancy of a child born in Birmingham in 2011 would improve by around 2.5 to 4 months for the same comparison.
Taking into account the UK Government’s projected future changes in air pollution concentrations from 2011 to 2030, the population would still be losing between 0.3 to 0.8 million life years after these air pollution changes in Birmingham (a life year is one person living for one year). Put another way, children born in 2011 are still estimated to die 2-7 months early on average, if exposed over their lifetimes to the projected future air pollution concentrations in Birmingham. Males are more affected than females. This is due to the fact that men have higher death rates and die earlier than women.
The report provides figures for both PM2.5 and NO2 separately but then uses one or the other as the best indicator pollutant rather than adding results together to avoid large overestimation (details in the report below). The ‘best indicator’ approach may result in a small underestimate.
Economic costs
Economists assign monetary values to the health benefits in order to compare the benefits with the real costs of implementing a package of policies. The largest proportion of the monetary value comes from a survey asking 170 members of the public how much they would be willing to pay to reduce their risk of experiencing a loss of one month of life (in good health) due to air pollution. Added up across time, people and the total health effects, this is then used to represent the amount society thinks should be spent to reduce these risks. NHS costs and loss of productivity are not included.
The monetized benefits over a lifetime of improvements to future anthropogenic PM2.5 and NO2 concentrations, compared with 2011 concentrations remaining unchanged, has been estimated to be up to £240 million on average/year (at 2014 prices).
Despite the projected future improvements in air pollution concentrations from 2011 to 2030, the economic health impact costs in Birmingham over a lifetime are still between £190 - £470 million on average per year.
These are what is called ‘annualised’ figures - a term for an average per year when the result is not the same every year. They are not actual costs but a measure of the amount of money society believes it would be reasonable to spend on policies to reduce air pollution (for avoiding adverse health effects of the remaining pollution) or was reasonable to have spent on policies that have already reduced air pollution.
Mortality burden (long –term exposure)
Mortality burden calculations are a simplified calculation at one point in time. They are not suitable for analyzing several years in succession because they do not have a mechanism for allowing the number of deaths the year before to influence the age and population size the following year (lifetables do this, see impact calculations above). Nonetheless, they provide a useful feel for the size of the air pollution problem.
In 2011 in Birmingham the equivalent of between 570 to 709 deaths are estimated to be attributable to air pollution (anthropogenic PM2.5 and NO2). These deaths occur mostly at older ages, as is typical for deaths in the general population.
The results varied by constituency with highest in Erdington and lowest in Hall Green. The ranking by constituency did not fully follow the ranking in pollutant concentrations. This is because the results are also influenced by variations in death rates by constituency, which in turn are driven in part by the proportion of elderly in the population and the level of deprivation.
The results for both life years lost after pollution improvements and attributable deaths from 2011 are smaller than the results for Greater Manchester from a 2018 report, primarily due to the smaller population in the smaller area of Birmingham city (around 1 million compared with 2.7 million for Greater Manchester). But they are not as much smaller as the population would predict due to higher pollution concentrations in Birmingham City. This also shows in the fact that the loss of life expectancy (which is independent of population) is greater in Birmingham than in Manchester. Gains in life years are smaller in Birmingham City than in Greater Manchester, again mainly due to population and the similar proportional reduction in pollution concentrations over time.
Limitations
The main report presents a wider range of uncertainty around the results for the mortality burden, mortality impacts and economic costs than the figures shown here.
The study was focused on air pollution changes within the Birmingham city area. Reductions in emissions will also have benefits for air pollution concentrations in the wider region (the West Midlands and beyond). For example, reductions in NOx emissions will reduce nitrate concentrations and thus PM2.5 concentrations in the wider region. The health benefits of this are not reflected here, although they are likely to be smaller than those in the city itself.
There will be further impacts from ozone concentrations. The long-term ozone exposure (representative of summer smog ozone concentrations metric) is projected to decrease over time compared with 2011 but less than other pollutants such as NO2 and PM2.5.
This study addressed the effect of air pollution on deaths and loss of life-expectancy. This included all causes of death grouped together so covers, for example, respiratory, lung cancer and cardiovascular deaths for which there is good evidence for an effect of air pollution. It does not, however, cover the effect of air pollution on health where this does not result in death. So well established effects (such as respiratory and cardiovascular hospital admissions, effects on asthma, low birth weight etc) and other outcomes more recently potentially linked with air pollution (such as dementia) are not included. Their inclusion would increase the benefit of policies to further reduce air pollution.
