Clearing the air
Recently we have been reading the excellent book Clearing the Air by Tim Smedley. Smedley is a journalist with a keen interest in air pollution, and the book takes the reader through many aspects of air pollution: the basic chemistry, causes, politics, and most importantly, what to do about it. It’s a great read - a rare triumph of a book that both of us have completed from cover to cover! While Smedley covers many issues, we thought we would highlight a few that we found most interesting.
Going back in time
1952 was the year of the great smog of London. Smog, caused by the burning of coal in homes and power stations in central London reduced visibility down to one yard. The smog was estimated to be responsible for excess deaths of 3000 in just one week - more casualties than any bombing campaign of the second world war. This led to the 1956 Clean Air Act, a globally significant piece of legislation. Smedley also covers an interesting aside: going even further back, London’s smogs inspired Monet’s famous and atmospheric paintings (so I suppose you could say something good came of them!)
Fast forward 70 years and wood burning now accounts for 25-30% of urban derived PM2.5* - domestic wood burning has become the single biggest source of small particle air pollution in the UK, exceeding that of road traffic. Wood burning stoves have been rebranded as biomass burners and have the feel of an environmentally friendly product, but in reality the particulate emissions are equivalent to a 7.5 tonne truck idling outside your home.
Crazy bad
Smedley tells the story of China’s chequered relationship with air quality. In 2019 China was ranked as the 11th dirtiest country in the world. The US embassy in Beijing started publishing air quality readings and had set 500 micrograms per m3 for PM2.5 as “crazy bad”, not expecting it to be breached. In November 2010 it was indeed breached, and in 2013 even went above 800. This was branded the “airpocalypse”. Lung cancer rates had gone up even as the levels of smoking had gone down: air pollution was equivalent to smoking 25 cigarettes a day or more, including for babies and children.
Travel planning
Smedley dedicates a large chunk of the book to the problems caused by diesel: how some countries, particularly European ones, ended up promoting diesel over other fuels. The root cause is found in the 1992 Kyoto Protocol where nations committed to reducing CO2 emissions in an effort to mitigate climate change. Despite laudable aims, this shifted to what appears to be a terrible policy decision to promote diesel as a more efficient fuel, even though it is far worse in terms of particulate matter (anything from 10 to 100 times worse). It was also worse on NO2, although car manufacturers claimed improved technology would lead to reduced emissions.
Then enter the VW scandal where that company (and others) falsified the results of air pollution tests, which bore no resemblance to pollution caused through actual road use. This was uncovered and diesel is now no longer fuel of the month - but huge damage was done over decades.
Moving to a more positive story, Smedley is electrified by the potential for electric vehicles. As we’ve discussed elsewhere, they are seen as a double edged sword - no NO2 or CO2 but still create lots of particulates, potentially even more due to their increased weight. Smedley’s claim is that if the particulates given off are not combustible (because we’ve eliminated petrol and diesel cars) then the health impact is much less. We think the jury is still out on this.
*Depending on your source. Tim Smedley quotes 31%, this gov.uk website quotes 25% in 2020