January 19, 2013

Stop the Smog: use cleaner coal and diesel.

I've been thinking about Chinese moms: the ones living in large cities, who have recently had to cope with their families living inside a thick pall of smog. Megacities don't have the cleanest air in the best of times, and for places like Beijing these are not the best of times.

Smog contains many gaseous chemicals that are bad for you, but the most worrisome part of the pollution are the small particles (soot and aggregates) that can penetrate deeply into the lungs and cause breathing problems, exacerbate asthma, and even lead to lung cancer. The smallest particles, the ones that cause the most trouble, are those of a size 2.5 micrometers (µm) or smaller, and are referred to as PM2.5.

Last weekend, the PM2.5 count was 993 µg/m3 (micrograms per cubic meter) by official measurements. That is an astounding 40 times the maximum of 25 µg/m3 recommended by the World Health Organisation. In the developed West, the latest proposed guidelines call for a limit of 18 µg/m3 in Europe (by 2020), and 12 µg/m3 in the US.

In the past week the PM2.5 counts in Beijing have eased, but over this weekend they have risen again, to around 400 µg/m3 earlier today.

Young children are especially at risk. Imagine the choice: it's either playing outside breathing bad air, or being cooped up inside all day. And after all this time, surely some of the pollution has made its way inside.

At least there is little of the wind that usually brings clouds of yellow dust, also laden with PM2.5, from the Mongolian desert. But the cold winter has increased the demand for energy, and a lot of that energy is provided by coal. China's reserves of clean coal, anthracite, are tucked in the country's north-western regions: both the higher grade and the transport required makes it more expensive than high-sulfur coal that burns much dirtier.

Just look at what happened in England in the early 1950s: in a short-sighted bid to increase national income, sorely needed after the world war, Britain started to export their cleaner, low-sulfur coal. But they were left with high-sulfur coal for the domestic industries and for home heating. The result: London's Great Smog of 1952, in which policemen had to use their lanterns to lead pedestrians, cars and buses down the streets because it was impossible to see more than a few tens of feet ahead. The photos of that time are amazing.

Similarly, Pittsburgh and other places in the US Steel Belt were blanketed by thick smog throughout the 1940s, and when households and industry finally switched to the more expensive low-sulfur coal, the air quality improved markedly, and acid rain was reduced.

China's infrastructure is up to date and of high quality, but the strong downward price pressure of the open market strongly favours the use of cheap fuel.

But like all industrialising nations, China is discovering that using the cheaper but dirtier coal is not a good long-term solution. For one, it's less energy efficient. And if you factor in productivity lost from having periodic emergency shut-downs (to reduce emissions) and the increased health care costs, high-sulfur coal may not be cheaper after all.

The same holds for the use of diesel, which is makes a large contribution to the smog, and for the same reason: Chinese diesel still has sulfur content higher than the government goal of 300ppm, in some cases far higher, leading to serious particulate matter pollution. The sulfur poisons catalytic converters and other scrubbers in the exhaust line of diesel vehicles, so Chinese diesel trucks and cars simply don't have scrubbing technologies installed, and still belch the black smoke that was so characteristic of 18-wheeler trucks in the US back when American diesel contained up to 500ppm sulfur.

It doesn't help that a lot of Chinese diesel, as it happens in so many other developing countries, is often adulterated with cheaper additives that can wreak serious damage on the engines, which then start to limp around much less efficiently. More often than not, the owners simply can't afford a replacement.

Yes, clean diesel is more expensive. Its regulation, including quality control, will hurt the economy. To help ease the pain, perhaps one way forward would be to adopt the Brazilian model, where diesel sold in metropolitan areas are required to have significantly lower sulfur content than in the less densely populated countryside.

But something has to change, and the sooner the better. There aren't that many children in China, compared to the total population. My guess is that Chinese moms, if consulted, would put the health of their children before the health of the economy.




  1. Wow ... that picture is just shocking. In truth I never thought much about what, exactly, is in smog. It's disgusting and I think if more people really knew ... they certainly wouldn't want to breathe it in and just might insist that it isn't part of their environment. Thank you so much for this post!

    1. I am hopeful that all this unacceptable smog will lead to something positive in China. After all the London smog of 1952 led directly to a Clean Air Act, and similarly here in the US. Here is an amazing picture of St Louis, MO before and after air quality regulations were put in place (no. 8 of 22 slides): http://www.treehugger.com/slideshows/environmental-policy/think-air-quality-regulations-dont-matter-look-pittsburgh-1940s/page/8/#slide-top

    2. OMGoodness ... the before and after of St Louis is just amazing! Well, it certainly gives one hope! Now if we could just be forward-thinking and prevent it before it gets so bad that we have no choice.


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