GeoLog

particulate matter

An overnight train view of China’s Anthropocene – Part 1

An overnight train view of China’s Anthropocene – Part 1

The nighttrain from Shanghai to Beijing is a comfortable affair. The train is new and clean. My travel partner and I can charge our phones and relax on soft beds. The railway is almost frictionless, and overall the experience is similar to any ride in the West. But outside, as the vehicle roars through the early night, things become increasingly hazy. As we reach further out from the Shanghai metropolis there is a slow realisation that the urban air-polluted luminous glow would not be left behind.

For those who have yet to visit China, it’s hard to truly convey the extent of the air pollution problem. During our time in Shanghai the smog was all encompassing; we could feel it settle on our skin and invade our lungs with every breath. Outdoors there was no escaping it. The Chinese air pollution forecast designated the risk level ‘moderate,’ and we wondered what ‘high’ would entail.

Inside the train we lay on opposite bunks. I fixed the window blind ajar to keep a sleepy eye on nighttime tree tops and apartment blocks as we dart by. We passed endless residential towers as we edged by cities we would never become familiar with, some of which appear desolate, almost entirely unlit, but I can’t imagine for long. Once we passed directly under a giant coal fired power station and by countless fields illuminated in the haze by nocturnal agriculture. There are trucks loading at 3 a.m. Along this 1200 km stretch – think Paris to Madrid – the foggy dim light rarely ceded.

This true-color image over eastern China was acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS), flying aboard NASA’s Aqua satellite, on Oct. 16, 2002. The scene reveals dozens of fires burning on the surface (red dots) and a thick pall of smoke and haze (greyish pixels) filling the skies overhead. Credit: NASA (via Wikimedia Commons)

My traveling companion is a children’s doctor. She raised her concerns: what chance do children born in these cities today have of living long healthy lives? Will they live full lives breathing in this industrial gunk? She explained to me that respiratory diseases kill because of chronic inflammation in the lungs, similar to that experienced from exposure to cigarette smoke. Such inflammation can in time lead to reduced lung function and, consequently, increased pressure on the heart due to less oxygen intake. Then, as the heart works harder to introduce the oxygen the body needs, it can fail, leading to premature death.

Estimates on health issues relating to long-term exposure to air pollution in China are hard to come by. It’s also hard to assess how dangerous such exposure is, but it’s likely China will experience an epidemic of respiratory related illnesses in the near future. One recent study reported that the Chinese population will suffer about 1.6 million premature deaths each year due to air pollution. As well as the human cost of lost loved ones, these air pollution related health risks will become a tremendous financial burden on the national health system. In 2007, The World Bank estimated that the annual health cost of outdoor urban air pollution in China for 2003 was between 157 and 520 billion Chinese yuan, around 1-3% of China’s gross domestic product.

However, this year China announced it would, for the first time, introduce a human health air pollution watchdog. According to Chinese officials, this is the first attempt by the national government to address how pollution affects public health. One day, scientists will be able to report on how generations born today can benefit from such endeavours. But for now, the future remains uncertain.

This is Part 1 of a two-part series on the impact of air pollution in China and the country’s steps to usher a clean era for the 21st century. Keep an eye out for Part 2, appearing next week on Geolog.

By Conor Purcell, a Science & Nature Writer with a PhD in Earth Science

Conor Purcell is a science journalist with a PhD in Earth Science. He is the founding editor of www.wideorbits.com and can be found on twitter @ConorPPurcell and some of his other articles at cppurcell.tumblr.com.

Editor’s note: This is a guest blog post that expresses the opinion of its author, whose views may differ from those of the European Geosciences Union. We hope the post can serve to generate discussion and a civilised debate amongst our readers.

GeoSciences Column: Is smoke on your mind? Using social media to assess smoke exposure from wildfires

GeoSciences Column: Is smoke on your mind? Using social media to assess smoke exposure from wildfires

Wildfires have been raging across the globe this summer. Six U.S. States, including California and Nevada, are currently battling fierce flames spurred on by high temperatures and dry conditions. Up to 10,000 people have been evacuated in Canada, where wildfires have swept through British Columbia. Closer to home, 700 tourists were rescued by boat from fires in Sicily, while last month, over 60 people lost their lives in one of the worst forest fires in Portugal’s history.

The impacts of this natural hazard are far reaching: destruction of pristine landscapes, costly infrastructure damage and threat to human life, to name but a few. Perhaps less talked about, but no less serious, are the negative effects exposure to wildfire smoke can have on human health.

Using social media posts which mention smoke, haze and air quality on Facebook, a team of researchers have assessed human exposure to smoke from wildfires during the summer of 2015 in the western US. The findings, published recently in the EGU’s open access journal Atmospheric Chemistry and Physics, are particularly useful in areas where direct ground measurements of particulate matter (solid and liquid particles suspended in air, like ash, for example) aren’t available.

Particulate matter, or PM as it is also known, contributes significantly to air quality – or lack thereof, to be more precise.  In the U.S, the Environment Protection Agency has set quality standards which limit the concentrations of pollutants in air; forcing industry to reduce harmful emissions.

However, controlling the concentrations of PM in air is much harder because it is often produced by natural means, such as wildfires and prescribed burns (as well as agricultural burns). A 2011 inventory found that up to 20% of PM emissions in the U.S. could be attributed to wildfires alone.

Research assumes that all PM (natural and man-made) affects human health equally. The question of how detrimental smoke from wildfires is to human health is, therefore, a difficult one to answer.

To shed some light on the problem, researchers first need to establish who has been exposed to smoke from natural fires. Usually, they rely on site (ground) measurements and satellite data, but these aren’t always reliable. For instance, site monitors are few and far between in the western US; while satellite data doesn’t provide surface-level concentrations on its own.

To overcome these challenges, the authors of the Atmospheric Chemistry and Physics paper, used Facebook data to determine population-level exposure.

Fires during the summer of 2015 in Canada, as well as Idaho, Washington and Oregon, caused poor air quality conditions in the U.S Midwest. The generated smoke plume was obvious in satellite images. The team used this period as a case study to test their idea.

Facebook was mined for posts which contained the words ‘smoke’,’smoky’, ‘smokey’, ‘haze’, ‘hazey’ or ‘air quality’. The results were then plotted onto a map. To ensure the study was balanced, multiple posts by a single person and those which referenced cigarette smoke or smoke not related to natural causes were filtered out. In addition, towns with small populations were weighted so that those with higher populations didn’t skew the results.

The social media results were then compared to smoke measurements acquired by more traditional means: ground station and satellite data.

Example datasets from 29 June 2015. (a) Population – weighted, (b) average surface concentrations of particulate matter, (c) gridded HMS smoke product – satellite data, (d) gridded, unfiltered MODIS Aqua and MODIS Terra satellite data (white signifies no vaild observation), and (e) computer simulated average surface particulate matter. Image and caption (modified) from B.Ford et al., 2017.

The smoke plume ‘mapped out’ by the Facebook results correlates well with the plume observed by the satellites. The ‘Facebook plume’ doesn’t extend as far south (into Arkansas and Missouri) as the plume seen in the satellite image, but neither does the plume mapped out by the ground-level data.

Satellites will detect smoke plumes even when they have lifted off the surface and into the atmosphere. The absence of poor air quality measurements in the ground and Facebook data, likely indicates that the smoke plume had lifted by the time it reached Arkansas and Missouri.

The finding highlights, not only that the Facebook data can give meaningful information about the extend and location of smoke plume caused by wildfires, but that is has potential to more accurately reveal the air quality at the Earth’s surface than satellite data.

The relationship between the Facebook data and the amount of exposure to particular matter is complex and more difficult to establish. More research into how the two are linked will mean the researchers can quantify the health response associated with wildfire smoke. The findings will be useful for policy and decision-makers when it comes to limiting exposure in the future and have the added bonus of providing a cheap way to improve the predictions, without having to invest in expanding the ground monitor network.

By Laura Roberts, EGU Communications Officer

References

Ford, B., Burke, M., Lassman, W., Pfister, G., and Pierce, J. R.: Status update: is smoke on your mind? Using social media to assess smoke exposure, Atmos. Chem. Phys., 17, 7541-7554, https://doi.org/10.5194/acp-17-7541-2017, 2017.