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The geography of smog

La Grande Smoke. Paris goes hazy (well, hazier) La Grande Smoke. Paris goes hazy (well, hazier) Ditty About Summer
19 Mar
As increased pollutant levels hit London and Paris, Geographical looks at how the smoky haze affects the world

For decades, smog seemed like an anachronistic problem that existed in Victorian-set movies or in the world’s new industrial heartlands.

Back in 1952, the Great Smog caused an estimate 4,000 premature deaths and made another 100,000 people ill in London. But the problem faded out over the next decade as the Clean Air Acts began to make to cut smog-producing emissions.

But if certain reports are to be believed, smog is back. And it’s trending on Twitter.

However, despite the visible levels of concern, according to the Met Office blog, smog isn’t really back as such in the UK. ‘It’s worth noting that the current air quality issues don’t fit any scientific definition of smog – which is a term that describes a mixture of smoke and fog,’ it says, adding ‘The air pollution is also nowhere near record levels – in fact, we saw higher levels than this during a period of poor air quality at about the same time last year.’

DEFRA’s UK air pollution map shows elevated pollution levels in some parts of the country. While this is not great news, the situation is still better than in China.

‘China faces severe air pollution problems similar to those that the western countries faced in early to mid-20th century. However, today’s China does not need to rediscover all the scientific knowledge and reinvent all the technologies to resolve its problems,’ notes an article in January’s Journal of Thoracic Disease.

‘Lessons learned’ is the article’s title, but last year’s Saharan-influenced London air pollution and this week’s Paris-to-London ‘smog’ show that it’s always worthwhile being prepared.

There are new technologies to reduce smog, new monitoring methods and smog problems emerging in unexpected places. All valuable lessons in the struggle to control air pollution.

Roof tile tech

In Southern California, 500 tons of nitrogen oxides are emitted daily in the South Coast Air Quality Management District coverage area, which includes all of Orange County and the urban portions of Los Angeles, Riverside and San Bernardino counties.

One possible solution to the problem may lie in coating roof tiles in titanium dioxide, a material that breaks down nitrogen oxide. A single roof can eat the equivalent of a single car’s nitrogen oxide emissions over 11,000 miles.

LA smog masksIn 1955, long before Chinese artist Ai Weiwei wore a gas mask to highlight Chinese pollution, LA citizens had the same idea (Image: UCLA Special Collections)

The engineers behind the project suggest that 21 tons of nitrogen oxide would be eliminated daily if tiles on one million roofs were coated with the titanium dioxide mixture. The total cost would equate to $5 for enough to coat a single average-sized residential roof.

Roof tiles may not be the only option for absorbing nitrogen oxide. As a next step, the team wants to see what happens when titanium dioxide is applied to house paint.

Hajj haze

Three to four million people visit Mecca during the Hajj pilgrimage each year. A whole extra city is added to Mecca’s 1.6m. The problem is that this intensifies the pollution that already exists.

‘We measured among the highest concentrations our group has ever measured in urban areas – and we’ve studied 75 cities around the world in the past two decades,’ says Isobel Simpson, a UC Irvine research chemist.

A collaboration between scientists in the US and Saudi Arabia measured air quality during the 2012 and 2013 Hajj seasons at roadsides, tents and narrow tunnels leading to the grand mosque.

AHMAD FAIZAL YAHYAAir conditioned tents during the Hajj (Image: Ahmad Faizal Yahya)

The worst spot was inside the Al-Masjid Al-Haram tunnel, where pilgrims on foot, hotel workers and security personnel are exposed to fumes from idling vehicles, often for hours. The highest carbon monoxide level – 57,000 parts per billion – was recorded in this tunnel during October 2012. This was more than 300 times regional background levels.

‘There’s carbon monoxide that increases the risk of heart failure. There’s benzene that causes narcosis and leukaemia,’ says Simpson. ‘But the other way to look at it is that people are not just breathing in benzene or CO, they’re breathing in hundreds of components of smog and soot.’

Besides vehicle exhaust, other likely culprits include gasoline high in benzene, a lack of vapour locks around gas station fuel nozzles, and older cars with disintegrating brake liners and other parts. Coolants used for air-conditioned tents sleeping up to 40 people also contribute to greenhouse gas build-up.

Saudi officials are aware of the issues and taking steps to address them, such as working to reduce benzene in area gasoline supplies. Directing Mecca pedestrians and vehicles to separate tunnels would be the best solution.

Social smog trail

Weibo, China’s answer to Twitter, has been used to uncover real-time information about air pollution levels in Chinese cities. The approach cannot forecast future air quality, but it can provide accurate, real-time information for the Air Quality Index (AQI).

Between 350,000 and 500,000 Chinese citizens die prematurely each year because of air pollution, according to the The Lancet.

For 30 days, a team from the University of Madison-Wisconsin monitored Weibo posts from 108 cities to see how often people complained about the air. The group analysed the text of the posts, as well as a time-and-space correlation among cities and days.

Large Chinese cities have monitoring stations to check on air quality, but smaller cities don’t usually go to the trouble. The researchers showed how Weibo could be used to estimate levels of air pollution in real time and with significant accuracy without using physical monitoring devices.

The team monitored Weibo posts to see how much people complained about the air. The group considered the text content of the posts, as well as a time-and-space correlation among cities and days.

Europe’s Vulnerable lungs

Last year, new data identified a link between higher levels of exposure to air pollution and deteriorating lung health in adult European citizens.

The European Study of Cohorts of Air Pollution Effects (ESCAPE) project supported previous findings that showed children growing up in areas with higher levels of pollution have lower levels of lung function and a higher risk of developing coughs and bronchitis. People suffering from obesity were also particularly vulnerable to the negative effects of air pollution, possibly due to an increased risk of lung inflammation.

‘Although the levels we see in Europe are much lower than in the so-called megacities in China and India, we are still seeing a deterioration of lung function in people exposed to higher levels of air pollution and this must be addressed,’ says Nicole Probst-Hensch, senior author on the project.

jtd-07-01-003-f1How air quality affected mortality in London during the Great Smog (Image: NCBI)

The World Health Organization estimated that air pollution caused seven million premature deaths in 2012, with 3.7 million connected to poor outdoor air quality.

‘Urgent action is needed to tackle air pollution in Europe,’ says Peter Barnes, President of the European Respiratory Society. ‘It is crucial that policymakers in Europe take note of these findings and update guidelines in Member States to meet the WHO recommended air quality standards. This will ensure equal protection of all citizens’ health across the continent.’

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