This week marks the 70th anniversary of the London Smogs of December 1952 – the ‘pea soupers’ which brought normal activity to a halt across the capital, and led to a large spike in hospital admissions and deaths.

These pollution episodes were driven by burning high sulphur coal to generate power and heat homes in city centres, exacerbated by cold winter weather (smoke + fog = smog). This was a very visible challenge. The ensuing Clean Air Acts focussed on removing these key pollutant sources to make our air cleaner.

The air we breathe today is much cleaner than in 1952 – but is it clean enough? Poor air quality contributes to over 30,000 premature deaths in the UK each year, mostly through impacts on circulatory and respiratory health, and costs us £20 billion This does not include the costs of reduced of quality of life, or conditions where evidence of links to pollutant exposure has emerged in recent years, including cognitive decline and dementia. The greatest burden of health harms is due to long-term exposure to fine particles – less than 30 times the diameter of a human hair and invisible to the naked eye.

Current air quality challenges are driven by different pollutant sources, including road transport...our research quantifies ‘real-world’ on-road emissions from vehicles on Birmingham’s roads and identifies the chemical fingerprint of particles to quantify these different sources."

Dr Suzanne Bartington & Professor William Bloss, University of Birmingham

This year’s Chief Medical Officer’s Annual Report from Prof Chris Whitty, published today, focusses on air quality. The CMO’s report suggests we still need to go further to reduce air pollution and protect health. The report sets out a need to focus air quality improvements on the places where people live, work and study, including indoor environments – reflecting a shift towards interventions which deliver the greatest health benefits. This approach recognises that in many of these are public spaces, indoors and outdoors; people are exposed to air pollution but can do little about it individually, so society needs to act.

Current air quality challenges are driven by different pollutant sources, including road transport and a range of sources of fine particles including combustion for power generation and industry, agricultural activities, cooking and heating in our homes, and wood and solid fuel burning. Our research quantifies ‘real-world’ on-road emissions from vehicles on Birmingham’s roads and identifies the chemical fingerprint of particles to quantify these different sources. Progress in reducing domestic emissions may be challenged if contemporary cost-of-living pressures and energy price increases cause people to rely on solid fuel and wood combustion to heat their homes. It is important to note that, indoors, the optimal balance between ventilation, energy use and heat loss is a priority for reducing air pollution, preventing respiratory infections and achieving net zero. These scientific insights using advanced measurement and modelling techniques feed into development of local and regional environmental policies, within the national regulatory context.

National legislation in England, much derived from EU directives, sets limits for emissions from some sectors such as road transport and power generation. It also sets legally binding targets for outdoor air pollutant concentrations. If these target levels are exceeded, action is required to be taken by local or national government - for example, the Birmingham Clean Air Zone - to reduce levels of one specific pollutant, nitrogen dioxide gas, to levels to within limit values as quickly as possible. However, extensive research demonstrates that health impacts result from exposure at levels much lower than the current limits in England: the advisory WHO 2021 global air quality guidelines are four times stricter.

Seventy years on from the deadly London smogs, we are again on the verge of new legislation to protect people from the harms of air pollution. The Environment Act 2021 enables the government to set new targets for outdoor pollution levels – new threshold levels which should not be exceeded and new exposure reduction targets – intended to reduce population level exposure irrespective of baseline levels, by a future date. The combination balances fairness (improvement in the most polluted areas, which also tend to affect the least affluent communities) with achieving some benefit for everyone, even if air quality meets the threshold value. The level at which new Environment Act targets are set – they were expected by 31 October 2022 - will demonstrate the Government’s level of ambition.

Our work in the West Midlands supports regional policy operating in the national legislative context. We can simulate air quality changes expected from a given policy, such as specific traffic changes, and calculate the health benefit in terms of deaths and disease diagnoses for our population.

This allows policy choices to be optimised for maximum health benefits versus costs, and for their relative impacts across differently vulnerable communities to be determined (as the health impacts depend upon the nature of the underlying population) – reducing environmental health inequality. This upstream policy-focused work is complemented by new analytical approaches to isolate and quantify specific policy impacts on air pollution emissions, concentrations and exposure pathways – evidencing benefits achieved and supporting behaviour shifts.

The opportunity is to achieve meaningful air quality and health improvements through evidence-based policy choices. Many of these will also deliver climate co-benefits, as many air pollution sources involve burning fossil fuels – but while reducing carbon levels (CO2) involves global action, the air pollution benefits are national, regional and local, that's to say they are less dependent on action elsewhere. Our work is helping local and regional authorities, the NHS, sector bodies and other organisations to deliver these benefits.