No magic technology needed, just social technology

Remarking on the towering filters being installed alongside junctions in Delhi, York University’s Ally Lewis, professor of atmospheric chemistry, likened filtering outdoor air to “trying to air-condition a room with the roof off”. It is far better to prevent the air pollution in the first place.

… small changes in age-old methods can make a huge difference. Explosives and wrecking balls can be replaced by machines that slowly nibble away at the concrete and mist canyons that suppress dust at source. In a world first, in 2015 London created two low-emission zones in the central city, meaning only the most modern and low-polluting diggers and cranes can be used there.

… simply switching to electric cars will not mean pollution-free cities. The level of emissions they cause will depend on how the electricity to run them is generated, while brakes, tyres and roads all create tiny airborne particles as they wear out.

In the US, studies have shown that doubling the size of a road can simply double the traffic, taking us back to square one.

Fortunately the opposite happens too: motorists adapt when roads are taken away. Between 1973 and 2003, a 6km, four-lane elevated expressway took 170,000 vehicles per day into the heart of Seoul in South Korea. It was frequently congested. Instead of building more lanes, city authorities demolished the whole thing. Sceptics predicted chaos, but traffic in the centre decreased. The residents of Seoul adapted, many swapping to the subway.

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Audrey de Nazelle was part of a team that studied the pros and cons and found the health benefit of using [bikeshare] was 77 times greater than the increased risk of accident and inhalation of pollution. … “In studies comparing health benefits from technological approaches to reduce air pollution with walk/bike scenarios, we find 30 times greater benefits from physical activity.”

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Reducing our dependence on road transport gives a quadruple benefit, improving our health, tackling air and noise pollution and reducing emissions.

… even the cleanest wood-burners, such as those that meet new European Ecodesign standards, will emit as much particle pollution during a period of use as six modern lorries would driving for the same amount of time.

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Ammonia from fertiliser and farming is a major ingredient in many city smogs, especially in the springtime smogs that plague western Europe and many other parts of the world.

Gary Fuller, The Guardian¹