Air Quality in Des Moines and Beijing

Air quality in Beijing currently is among the worst in the world. The photograph above of the Beijing Olympic Stadium was taken several years ago. The photographer reported, “The grey here is not rain or cloud but thick, smelly smog.”

When you see the sun looking like it does in the second photo above (also taken in Beijing), the haze announces that the air is loaded with particulate matter. Particulate matter scatters light. In terms of beauty, particulate matter has two effects. First, it reduces the amount of light and hence reduces the danger of looking at the setting sun, and second, it bends the light so we see mostly the longer wavelengths - reds and oranges; but while particulate matter enhances the beauty of sunset photos, in terms of health it’s not so good. EPA gives a basic view. (The origin of particulate matter can be forest fires, volcanic eruptions, construction, activity or winds over farm fields, industrial activity, trucks and cars or road dust.) 

Particles in particulate matter can be of many sizes, but the ones of special interest for their health effects on the lungs are between 2.5 and 10 micrometers, and they are designated as PM10.  Wikipedia is useful for some of the definitions and details. 

Here is where Des Moines comes in.

The federal government monitors PM10 and posts results regularly for many cities including Des Moines. The target maximum for particulate matter (PM10) is 50 micrograms/cubic meter. In Des Moines we are hovering around that value this week. As of July 16 we were just  under the limit at 48 (which put Des Moines barely in the good air quality category), but on the 17th we were over limit at 67 (which edged us into the moderate air quality category). With rain, levels of particulate matter drop, and so Des Moines levels dropped below 50 again on Friday. According to a July 16 report from BBC Beijing is not meeting the PM10 standard, and Beijing (unlike Des Moines) is not hovering near acceptable levels. Beijing’s PM10 level on Sunday July 13 was 60 but Monday July 14 it was over 250. 

Because high particulate levels can cause irreversible lung damage, there is concern for Olympic athletes who will compete in outdoor events with long competition times (for example, steeplechase, marathon, soccer, cycling, rowing) or who will train outdoors. Athletes competing indoors like Shawn Johnson or in short duration events like Lolo Jones will be less affected.

Germany’s leading magazine Der Spiegel expresses concern. On the other hand Alex Pasternack of Huffington Post suggests that air quality will be a non-issue by time the Olympics start, and CBS News suggests the same. At a cost estimated by CBS News to be $16 billion China will shut down industry, halt construction, and ban half the cars (in a zone of 200 mile radius or larger) for two weeks prior and during the Olympics. An interesting question: If China is successful in reducing pollution levels so drastically on a temporary basis, will the people expect better air on a permanent basis? 

A relatively recent set of studies are indicating that a type of particulate matter that is smaller than the PM10 particulates can enter the blood stream and damage blood vessels.  (See AIRNow for definitions and USNews & World Report for a synopsis of the study.)

To read about the physical effects of particles on the lungs and how and why they are dangerous, I once again recommend a long but entirely readable article called Clearing the Air in Harvard Magazine in 2005. 

Credits: Photos on flickr by rytc (Olympic Stadium) and toesoxluxer (the sunset).

 Guest Writer: James G. Lindberg (Jim) is the Purple Wren’s sweetie and is a visiting chemistry professor at Grinnell College and retired from Drake University.