This weekend in Beijing, the air quality index broke historic records, summarized succinctly in the title of a New York Times story by Edward Wong, "On Scale of 0 to 500, Beijing's Air Quality Tops 'Crazy Bad' at 755." The South China Morning Post reports that the problem extended far beyond Beijing: "More than a dozen provinces were smothered by a dense, almost suffocating, smog yesterday, with pollution readings in many areas plunging to the worst levels in years."

Wong writes:

It was unclear exactly what was responsible for the rise in levels of particulate matter, beyond the factors that regularly sully the air here. Factories operating in neighboring Hebei Province ring this city of more than 20 million. The number of cars on Beijing's streets has been multiplying at an astounding rate. And Beijing sits on a plain flanked by hills and escarpments that can trap pollution on days with little wind.

A second New York Times reporter, Didi Kirsten Tatlow, looked at the pollution outside her window and wrote a blog post about how she was forced to keep her children indoors with four air purifiers turned up to 11. She nevertheless reached the conclusion that China is still "far less polluting than the United States." Her reasoning is based a fallacy that sadly was endorsed by the Supreme Court Massachusetts v. EPA decision, the belief that carbon dioxide is an air pollutant.

On several days when I visited Beijing in June 2009, the skies were so dark with pollution that drivers turned on their headlights, and the automatic sensors in streetlights were fooled into thinking night had fallen. It looked like an intense thunderstorm was imminent, but no cleansing rain arrived.

On Saturday levels of particulates and other pollutants soared well past those I experienced, or that raised international concerns during the 2008 Olympics. Measurement at the U.S. Embassy in Beijing was 755, referred to officially as "Beyond Index," or informally as "crazy bad." The Environmental Protection Agency measures air quality on a scale from 0 to 500. Levels between 301 and 500 are "Hazardous;" according to AirNow.gov, the Obama administration's new air quality monitoring website, these levels "would trigger a health warnings of emergency conditions. The entire population is more likely to be affected." Beijing residents described the conditions as "postapocalyptic," "terrifying" and "beyond belief."

For comparison, AirNow.gov publishes a daily map of the Air Quality Index for the contiguous United States. On Jan. 14, 2013 the entire map was nearly all green ("Good" or 0-50), with a few yellow patches("Moderate" or 51-100), and four locations labeled "Unhealthy for Sensitive Groups" (101-150). Olympia-Lacey-Tumwater, Washington, was the only "Unhealthy" area, 151-200 on the scale.

In other words, last weekend's air pollution in Beijing was 5 to 7 times the worst reading in the United States. This is not surprising since wealthy capitalist democracies have resources and political will to invest in clean air.

The EPA lists five major contributors to air pollution: Ozone, Particulate Matter, Carbon Monoxide, Nitrogen Oxides, Sulfur Dioxide, and Lead. The factories and cars mentioned by Mr. Wong together emit all these toxic substances. One additional particulate not mentioned in the Times is the windblown dust from Gobi Desert sand dunes, exacerbated by desertification of the area north and west of Beijing.

Ms. Tatlow, the Times blogger, does not consider any of these real dangers but rather switches the conversation to the imaginary danger of carbon dioxide, which does not appear on the EPA list:

In 2011 China produced 9.7 million kilotons of carbon dioxide, nearly double United States' 5.42 million kilotons... Germany was the sixth most polluting nation in the world, with the United States the second and China the first, according to the chart.

But something else stands out here: China's population of more than 1.3 billion is about 4.5 times that of the United States' approximately 300 million. So though it leads the world in carbon dioxide emissions, it is still, per capita, far less polluting than the United States.

To begin with, per capita figures are essential for many comparisons, but irrelevant in this case; the air in Beijing is dangerous to breathe, no matter what the population of China -- or the price of tea. Carbon output to GDP would be a more meaningful comparison, but this wouldn't be perfect; the carbon-intensive industrial sector is 28% of the German GDP, compared to 19% in the U.S. Using per capita figures however is useful if you wish to blame America first.

More importantly, carbon dioxide, as any kid who got a C in high school chemistry can tell you, is colorless, tasteless, non-toxic, non-irritating to the skin, non-carcinogenic, with no known harmful effects of chronic exposure. (Good thing, since we are exposed to it constantly from birth to death.) Furthermore CO2 is essential for plant photosynthesis and the "primary source of carbon in life on Earth" (Wikipedia).Given that CO2 is a gas, it contains no particulates -- solid particles that damage the lungs.

Even if you fervently believe that emitting carbon dioxide will lead to catastrophic global warming, CO2 has nothing -- zero -- to do with the air pollution in Beijing. And it's not a mistake without consequences. China has a serious health problem to address, one that has effects carried past their national boundaries. If Beijing chooses to placate environmentalists by spending money on carbon dioxide mitigation and diverts resources from smokestack scrubbers and automobile pollution controls, the result will be unnecessary suffering, sickness and premature deaths.