Air quality limits, Geographic Air Pollution Causes

Hi everyone! Last week I wrote about air pollution, where it is bad, what causes it, and the main harmful components of air pollution.This week I am going to give you some exact numbers. First, though, let's start with a scary fact. Then I'm moving into how pollution goes away once it is in the air.

US limits on PM2.5 are 12 micrograms per cubic meter averaged over a year. In Europe, the limit is 25. Note that for every increase of 10 micrograms, there is an associated 9% increase in lung cancer incidence, and a .6 years decrease in life expectancy. Scary, right? China has an annual average limit of 40, and India has an annual average limit of 50. They don't do so well in some cases. Beijing averages 56, and Delhi averages 150. In other words, Delhi's population has somewhere in the vicinity of 10 years less of life from air pollution alone.

What about other pollution? SOx, NOx, and ozone tend to accompany each other. Wherever you have SOx, you have the other two. Even clean-burning natural gas power plants produce NOx, just as a by-product of combustion is our nitrogen atmosphere. NOx becomes ozone and smog when mixed with sunlight and organic radicals (the latter of which exist just about everywhere). In other words, these three things are difficult to separate. Moreover, they are often accompanied by PM2.5. Research is having trouble teasing them apart and figuring out what might cause what. But, again, SOx and NOx become strong acids when they react with the water in your lungs, and ozone is toxic to life at ground level (always remember, ozone 15km overhead blocks out the bad parts of the sun, ozone at ground level damages living things).

SOx and NOx, once emitted, are typically cleared out by rainstorms, creating acid rain. It's better than breathing it in, right?

SOx and NOx, once emitted, are typically cleared out by rainstorms, creating acid rain. It's better than breathing it in, right?

The US has pretty good air quality overall. But if you look at the US government website that shows current levels of pm2.5, you'll see some cities in the US are straight up awful. While their annual average might be around 20-25, on the day I checked, San Bernardino, CA, had 137 micrograms per cubic meter. This is absurdly high. On days like this, people will have difficulty breathing.

Los Angeles on a polluted day. Thanks Curtis Barnes for the correction! Site.

In other words, you can go almost anywhere in the world and find places that are tough to breath in. That being said, there are some countries that are really bad almost everywhere. Bangladesh, India, Nepal, China, and Pakistan are all very polluted. Much of the middle east is as well.

So what makes these things hang out? The most common reasons are inversions. It's when warm air sits on top of colder air. Since air likes to rise when it is warm, if there is a layer of cold air that is polluted that also happens to be capped by warm air, that cold layer will sit there and stagnate. Instead of blowing up or away, it will simply accumulate pollution. Another cause is being surrounded by mountains. Mexico City, for example, is right in the middle of a bunch of mountains. The pollution cannot rise above the mountains, so it lingers and builds. It is also common for coastal areas, or areas next to high deserts, to have times when air refuses to vacate. Those mechanisms are a bit complicated, so we won't discuss them. Finally, being near 30 degrees North or South latitude tends to make air pollution stick around. LA, for example, is at 34 North. The reason for this being bad is that the Earth has the giant airflow patterns. Air is heated at the equator by the sun, then it rises. Eventually it cools and falls near 30 degrees north. The result is that inversions happen more frequently, cause there is air pushing down on the cities.

Diagram of temperature inversion. Site

That's about it for the major causes of air pollution buildup. Of course there has to be pollution to start with for these effects to matter.

Hokay, so, what makes PM2.5 go away when it starts hanging around? Either a wind comes through and blows it out, or a rain comes through. Rain scrubs PM2.5 by absorbing it, and it chemically converts SOx and NOx to acids that become solutes in the rain. Hence acid rain. Also hence why skies are most clear after rains, and how they can smell so fresh and clean after rain. So, if you are going to go for a run in Beijing or Delhi, wait til after a big rainstorm 🙂

Let's talk about that last point a little bit more. China is dry nearly all the time. It doesn't rain much there, so it has a bigger problem of building up air pollution. India has the monsoon season, but is also fairly dry otherwise. What about LA? If you have ever driven in a slight rainstorm in LA, you will see that everyone freaks out and has no clue how to drive in the rain. It's hilarious for about 5 seconds until you realize you are now in a traffic jam. It doesn't rain there, either.

So. Your most polluted places will be near 30 degrees latitude, potentially on the coast or in mountains, dry, and in the vicinity of polluting vehicles, industry, or power plants. Neat. right? I bet you thought it was just pollution alone that caused pollution to linger.

Hokay, that's all for now. Thanks for reading!

- Jason Munster

 

China, Accounting Pollution in Manufacturing, and Greenwashing

A Call for a Consumption Based Pollution Levy: Pollution from Chinese Export Manufactures Drift to US West Coast

Pictured here is a NASA image of smog in China. Nearly all the gray is smog. This is a result of the rise of manufacturing, and rapid production of low-quality power plants

Guys, no science in this one. Also, stay tuned for a better treatment of this topic from Archana Dayalu over at Policylab. I originally wrote this for policylab, but it turns out Archana had the same idea earlier. Hence you'll notice a completely different writing voice (it's not the fun one I use in my blog).

As I wrote in the past, outsourcing of manufacturing jobs allows the US to push all the pollution in manufacturing into other countries while enjoying lower prices of goods manufactured by cheap labor. Thanks to Kate Wang for bringing a recent NYT article to me attention.

An early edition report from the Proceedings of the National Academy of Sciences (PNAS) shows that a significant amount of pollution drifts from China to the west coast of the United States. The authors argue for a changing of attribution of the associated pollutants to the consuming countries, rather than China, the producing country. The authors gloss over any potential impacts this would have on world trade. Lead author Jintai Lin writes:

Atmospheric modeling shows that transport of the export-related Chinese pollution contributed 3–10% of annual mean surface sulfate concentrations and 0.5–1.5% of ozone over the western United States in 2006. This Chinese pollution also resulted in one extra day or more of noncompliance with the US ozone standard in 2006 over the Los Angeles area and many regions in the eastern United States. On a daily basis, the export-related Chinese pollution contributed, at a maximum, 12–24% of sulfate concentrations over the western United States.

In other words, goods manufactured in China and consumed by the United States directly cause pollution in the western United States. The upside is that the former heavy manufacturing centers in the Eastern United States have outsourced to China, cleaning up the air of the Eastern US. The article points out that, given the dense population of the east coast, this is a net win for the US, at slight expense of the west coast and great expense of pollutants in China.

Air pollution in Beijing. One picture taken on a clear day, another on a smoggy day. This is the capitol city of China. This is the ugly side of outsourcing.

It remains unclear what the author's ultimate goals are. There is no international accounting of pollution. Either the authors are greenwashing--the practice of trying to make manufacturing or other industry look environmentally more friendly through the process of bullshitting--or they are anticipating some accounting system, either internal to China or external, in the future.

The authors argue for a different method of accounting for pollution associated with manufactured goods. Currently, all pollution is attributed to the producer. Chinese factories build the goods, China gets assigned the pollution in international ledgers. Consumption based attribution, they argue, would make more sense. The goods are made for American (and otherwise) consumption, and the pollution should therefore be attributed to America.

Disregarding whether this is right to do, or whether it would accomplish anything more than green-washing China’s economy, let’s explore several of the implications of this policy change. Specifically in a hypothetical world that has to account for pollution contained within products, which, aside from green-washing, would be the major reason to worry about pollution attribution. Manufacturing of these export goods requires significant amount of energy. The sulphur and black carbon that reaches the west coast specifically come from coal-fired ower plants. China puts few controls on emissions from these power plants, and the required rate of construction results in power plants that are significantly less efficient than those in the US. This means that every bit of energy produced and used in China, for manufacturing or otherwise, contains more pollution than it would in the US or any other developed country. Moreover, Chinese manufacturing is less efficient than developed countries for a variety of reasons.

The end result is that a good manufactured in China embodies more pollution than the exact same good manufactured in the US, Japan, Korea, Europe, or any other advanced nation. If policies were put in place to move to a consumption-based attribution of pollution, and that attribution had real-world implications on the cost or value of a product, Chinese goods would face a competitive disadvantage. The implications are pretty straightforward: either China cleans up its manufacturing and energy sector, greatly benefitting China and slightly benefitting the rest of the world from a pollution standpoint, or goods are produced in countries where they can be made for less environmental cost, hurting China’s exports while healing its air quality and benefitting the rest of the world financially and environmentally.

While this attributing of pollution on the consumption side seems to mostly have net benefits, it only works if purchasers or producers are forced to pay for pollution they bring about. We are not currently in a world where either are held accountable for the pollution associated with manufacture of Chinese exports. In this, Jintai Lin’s suggestion seems only like greenwashing: an attempt of finger-pointing for the destruction of China’s air quality and environment.

Thanks for reading

- Jason Munster