The Odd Shapes of PM2.5

A recent episode of “Approaching Science,” a CCTV documentary series, discussed the smog that’s been choking the mainland for the past few years. The show interviews scientists and laypeople to paint a comprehensive picture of the challenges that air pollution is creating for the Chinese as individuals and as a society. Scientists are rushing to understand the problem and come up with effective responses before it’s too late—from smog warning signals to setting up cameras to track air visibility. One striking visual in the video is of an experiment demonstrating the difference between plants grown under artificial light (left, in the split-screen video below) and natural conditions (right).

He Dongxian of China Agricultural University, who conducted the experiment, explains, “The experiment makes clear that smog has a pronounced effect on the growth of the plants, because smog blocks out the sun. Less sunlight means the plants will grow more slowly. Growing plants inside winter greenhouses usually takes between 60 and 70 days, but with smog, it could take up to 90 days.”

Also, check out what PM2.5 particles look like under a 1000x microscope:


Good news for Beijingers is that 2016 is off to a good start—relatively speaking. Following a December which had some notoriously bad days, with awful air quality, January saw mostly blue skies.

 Beijing, December 2015 

 Beijing, January 2016

Even though January had just a few more blue sky days than December, if you look at how much dust an air filter can collect in its short life span, then you might start to appreciate even a slight improvement a lot more. Below is a foreign correspondent friend’s photographs of a couple of air purifier filters found in a unit left behind in a new residence by a previous tenant. She and her husband don’t know how long these filters had been used, but found them to be loud reminders of the importance of the filter to their family’s health.

How air filters look like upon retirement 

Cancer is now the leading cause of death in China, according to a chinadialogue story. Lung cancer is the most common form of cancer for both men and women, nationally. Lung cancer deaths in Hebei province have tripled in the past 40 years, compared with a 221 percent increase nationwide. Hebei is one of the provinces worst-affected by pollution. In the map below, it is the dark red province surrounding Tianjin and Beijing. The Ministry of Environmental Protection said the average PM2.5 reading in the Beijing-Hebei-Tianjin region in 2014 was 93 micrograms per cubic meter, almost three times the official safety standard of 35 micrograms per cubic meter and nearly four times the maximum levels recommended by the World Health Organization.

(Image courtesy of NASA Earth Observatory)

Hebei is home to the six most-polluted cities in the country. Baoding, home to more than 10 million people, has the dubious honor of ranking first. The unusually severe pollution in the province is due to the burning of over 300 million tonnes of coal annually, almost 10 percent of the national total. Last year, the provincial government set the goal of cutting coal use in half by shutting down the coal-fired boilers used to produce heat outside the big cities. But in a province where more than half of days are accompanied by smog, much work remains to be done.

David O’Connor contributed research.