Ever since lockdowns took effect in cities across the world, air quality experts have been eagerly awaiting the statistics for March and April 2020. Weeks of greatly reduced road traffic have led to hopeful predictions of corresponding drops in emissions of pollutants like nitrogen oxides (NOx). We know from WHO reports that air pollution is now a major cause of death and disease globally, and even with incentives to drive cleaner vehicles, the problem has often seemed intractable.
So, what have we learned from the great economic pause? The evidence is often contradictory and presents us with new questions to resolve before an effective post-pandemic policy response can be crafted. But a few initial conclusions can be drawn.
Despite air quality gains, residual emissions remain
It's worth remembering that no lockdown led to zero traffic, even in Italy and Spain where restrictions were most severe. A central question arises from the new data: how did an 80% drop in traffic activity lead to pollution falling by only half as much?
According to the European Environment Agency, Milan’s NO2 concentrations in the week 16-22 March were down 21%, compared to the same week last year. Similarly, NO2 concentrations in Madrid and Barcelona were 41% lower and 55% lower, respectively (EEA figures). Yet concentrations of fine particles (PM10), which are the most harmful to human health, have not reduced as much as NO2 concentrations.
Complicating things, while concentrations have fallen during the lockdowns, these lower levels of air pollution are not actually that unprecedented. We’ve seen these levels of NO2 and PM10 concentrations in previous summer months in normal times across major European cities, thanks to seasonal weather effects. Importantly, background PM10 concentrations have remained largely unchanged.
There are various reasons why air pollution has remained a stubborn reality. Private cars, public transport and goods vehicles have continued to operate to support essential services during the lockdown. These often diesel vehicles may be sufficient to sustain background concentrations, but more data is required to understand the true causes. The need to maximise walking and cycling, while shifting to electric vehicles for public transport and goods movements is certainly clearer than ever.
We risk the return of the private car
So, the lockdown air quality gains risk being partial and temporary. A large-scale return to private car use (out of ongoing safety fears, and limited public transport capacity) will jeopardise wider transport decarbonisation plans. It could also potentially reverse any gains made in air quality and undermine planning efforts to design urban places and spaces for people, not cars.
Ironically the lockdown proves people can make personal compromises for a bigger social goal. This should encourage leaders and transport planners to push for bold long-term changes that will reduce pollution and perhaps expand their ambitions on tackling climate change, another issue where personal behaviour change is key. Some cities like Bristol in the UK are announcing car bans for central areas, but individuals and businesses will need viable alternatives, ones tailored to their city or town, if they’re to make the right choices.
Pollution measurement must improve, everywhere
The last few months have been enormously useful to researchers and scientists, where the systems have been set-up to record air quality data. Not all cities measure pollutant concentrations as much as they should, and yet this data is a vital part of how clean air will be achieved. Without clear data, businesses and the public can’t understand the costs of travel choices and modulate behaviour. Air quality monitoring stations should be an immediate investment.
London and Newcastle have shown the value of low-cost sensor networks in providing accurate, reliable and real-time air quality measurements to decision makers. This is particularly important for those parts of our cities where we may be most concerned about exposure to poor air quality, such public places, schools and hospitals.
Active travel might not be enough (according to Copenhagen)
It remains clear that in the dense, commercial, residential urban fabric of our cities, it will be hard to meet existing health and climate change goals. Personal active travel choices won’t be enough to solve these issues. It will take a multi-faceted planning approach, and a long commitment to achieve. Copenhagen has demonstrated how to create a liveable, healthy and attractive city by integrating sustainable urban transport policies, including land use, public transport and cycling.
A licence to be ambitious
Beyond the statistics and findings, the lockdowns have brought air quality right back up the list of public priorities. With air pollution a co-factor for patients suffering from COVID-19 itself, the issue couldn’t be any more material. Decision makers have a license to take the current public awareness of what is possible, and the measures that might preserve the gains we’ve experienced and create bolder and more far-reaching policy.
Clean air requires collaboration
Despite our understandable hope for an air pollution miracle amid the dark reality of the pandemic, tackling the problem remains a multi-faceted undertaking. It depends on a global understanding of what works (and doesn’t), multi-disciplinary collaboration, and an evidence-based approach, gathered from innovative data sources and analysis tools. Talk to our team if you’re interested in applying this methodology to your city’s air quality problems.
Adapting to a COVID-19 world
The COVID-19 pandemic is a major shock to the world. The human cost is hard to bear and our thoughts are with all those affected. As engineers, designers and consultants we have a role to play - this is a moment to be brave, try new ideas and collaborate to develop services and facilities our communities need.