Thursday 17 June is Clean Air Day for 2021, and comes as the Birmingham Clean Air Zone begins to tackle road-transport related air pollution in the city centre. It is maybe ironic that this was once seen as an environmental solution: Around 125 years ago, one environmental challenge facing major cities was horse manure in the streets – with up to 100,000 horses working in the largest cities, this was a highly visible issue. The West Midlands is known for its contributions to the development of the motorcar, which transformed everyday living – alleviating this problem, but eventually leading to congestion, traffic jams and a less visible, but no less pervasive environmental challenge – the fight for clean air.
The Birmingham Clean Air Zone (CAZ) came into effect on 1 June, with charges now being levied for higher polluting vehicles entering the city centre. The CAZ is designed to target roadside pollution in the city centre – nitrogen dioxide gas, primarily from motor vehicles with older diesels being major emitters. This is a local challenge: most of the NO2 breathed in Birmingham is emitted within the city, so local actions reap local health benefits (as seen in the 2020 Covid lockdown-driven falls in NO2) – although care is needed to provide viable sustainable transport alternatives, and avoid displacing emissions outside the city and into other, potentially more vulnerable, backyards. As the vehicle fleet modernises, emissions of NO2 should fall, while increasing numbers of electric vehicles with zero tailpipe emissions – ahead of the national ban on sale of most petrol and diesel vehicles in 2030 – will help mitigate the NO2 challenge.
Our other air pollution challenge is fine particles suspended in the air: PM2.5, which are small enough to penetrate deep into our lungs and bloodstream. Particulates have a wide range of sources, including combustion, agriculture and transport, and affect people across the region, beyond the city centres - requiring more coordinated approaches regionally and nationally.
The UK’s air quality legislation sets an objective for PM2.5 concentrations of 25 ug m-3 (as an annual mean, outside Scotland) while the World Health Organisation health-based guideline is 10 ug m-3. The latest science shows there is no threshold for health effects from PM – any reductions deliver health benefits. Exposure to PM2.5 and NO2 leads to 28,000 – 36,000 premature deaths in the UK each year, while the CBI recently calculated that meeting the WHO guidelines for air quality could bring an annual £1.6bn economic benefit. These WHO guidelines – set in 2005 – are due to be reviewed, and will likely strengthen in response to growing evidence of the health impacts of air pollution. The UK Government will shortly update PM targets within the new Environment Bill – a key opportunity to set the level of ambition for cleaner air over the coming decades.
Setting a target is one thing, but getting there is another. Moving towards cleaner air will not be easy, and will require changes in how we move around, how we heat our homes, how we power our cities and our industry. However, many of the changes needed have links (co-benefits) with actions to tackle climate change – but act at different geographies.
Carbon emissions spread around the world and have global climate effects: CO2 levels in Birmingham are similar to those in Beijing and Bermuda, requiring concerted international action. Conversely, most air pollutants are removed by atmospheric processes in hours or days – so local actions reduce local air concentrations and bring local health benefits: Birmingham can enjoy the benefits of cleaner air, irrespective of what happens in Beijing (or Bermuda).
Many of our least advantaged communities suffer the poorest air quality, and are most vulnerable to its impacts, so prioritisation of measures can help reduce regional health and social inequalities. A careful balance is needed in national and regional policy between addressing the areas with the worst absolute air quality, and reducing exposure across the whole population. Provision of air quality data and knowledge to people and organisations affected – making the invisible challenge visible – is a key component of this process.
Urban environmental quality impacts on human health and happiness but also economic growth. Cities that are delightful places to live and are perceived to have desirable residential amenities attract and retain talented individuals and this then is reflected in high new firm formation rates, economic growth and job creation. Clean Air Day plays an important role in reminding us that the air we breathe across the West Midlands impacts on liveability and livelihoods across the region.
The WM-Air project at the University of Birmingham is measuring the sources of air pollutants, quantifying the air quality co-benefits from Net Zero actions, and working to evaluate air pollution health and economic effects across local communities – providing the science to enable policy choices which maximise the benefits from cleaner air.