Just in time to ring in the Year of the Dragon, a few days ago, Beijing’s infamously murky air gained a long-awaited official index: real-time measurements of the city’s PM2.5 levels.

PM2.5 (also known as soot) are microscopic particulate matter that contribute to the pea soup miasma of air pollution we can all do without. Diesel vehicles and coal-fired power plants are among the biggest sources of this type of pollution. Far from just causing thick layers of unsightly brown haze, PM2.5 is so small that it can worm its way past the body’s natural ability to expel foreign particles, lodging deep within the lungs and causing serious cardiovascular and respiratory harm—and even early death.

Up until last Saturday, the Beijing government only provided measurements of PM10, relatively larger particles which pose less of a threat to human health. Parties interested in the more informative PM2.5 levels relied on @BeijingAir, the mechanized roof-top resident of the U.S. Embassy who has been diligently tweeting PM2.5 and ozone levels at hourly intervals for several years.

The practice has long created controversy with the host nation. Leaked diplomatic cables from 2009 (Subject: "EMBASSY AIR QUALITY TWEETS SAID TO ‘CONFUSE’ CHINESE PUBLIC") revealed that Chinese officials found the unassuming @BeijingAir not just confusing, but also "insulting," as he graded Beijing’s air quality based on the Air Quality Index used by the U.S. Environmental Protection Agency. (Nevermind that PM2.5 reports from Beijing Municipal Environmental Protection Bureau were non-existent at the time.)

China Central Television Tower, shrouded in smog. (kalevkevad / Flickr)

The U.S. EPA provides AQI levels for the five major air pollutants regulated by the Clean Air Act, giving descriptors ranging from “Good” (numeric levels 0–50) to “Hazardous” (numeric levels 301–500). What’s beyond “Hazardous”? The EPA hasn’t yet shared with us a name for that territory, but apparently, it’s called: “Crazy Bad.”

@BeijingAir create a brief stir in November 2010, when the machine, faced with an off-the-chart PM2.5 concentration of 562 μg/m3, took some creative liberties, tweeting: "11-19-2010; 02:00; PM2.5; 562.0; 500; Crazy Bad". (In comparison, Earthjustice in San Francisco is today breathing in PM2.5 levels of 13.9 μg/m3.)

Embassy officials later offered that the measurement was considered so unbelievably out of range, that @BeijingAir’s programmers didn’t think the cheeky inside joke would ever see the light of day.

Thick haze, extending southward from Beijing along the coastal plain bordering Bo Hai and the Yellow Sea, blankets eastern China in early November 2011. Read full caption. (LANCE/EOSDIS MODIS Rapid Response Team / NASA)

Here in the United States, we have our own battles with PM2.5. The EPA will soon be required to update national health standards for PM2.5; the standards will become an important tool in cleaning up air and saving lives across the country. The options put forth by EPA staff scientists last April are far weaker than they can or should be. The recently released report Sick Of Soot from Earthjustice, the American Lung Association, and the Clean Air Task Force, gives a detailed look at why the standard should be strengthened to an annual standard of 11 μg/m3 and a daily standard of 25 μg/m3—a choice which could prevent as many as 35,700 premature deaths every year. (Why the need for both an annual and a daily standard? Find out by reading Sick Of Soot.)

Tom Frantz stands in his farm fields, in rural Kern County, CA. (Chris Jordan-Bloch / Earthjustice)

PM2.5 is not a theoretical problem. Millions of people across the country, like Tom Frantz of California’s Central Valley, Tommy Allred of Midlothian, Texas, and Marti Blake and Martin Garrigan of Pennsylvnia, are suffering from dangerously poor air quality every day. Fortunately, there has been some good news on the horizon. Just last week, San Joaquin Valley residents scored an important victory when a federal appeals court rejected an inadequate ozone air pollution plan.

Although Beijing’s official PM2.5 measurements are mere days on the scene, they are (unsurprisingly) raising eyebrows with their sanguine readings. (In one snapshot from this week: Officially: 30 μg/m3 v. @BeijingAir: 66 μg/m3.) The city went through extraordinary measures to improve air quality for the 2008 Olympics (factories were relocated or closed; residents could drive only on certain days of the week, based on their license plate number; and more) from its previously dismal levels. But unfortunately, as the Games ended, so did the trend of being able to breathe easier.

Last month, more than 700 flights in and out of Beijing were canceled—the weather was fine; it was the terrifically bad smog levels that dangerously cut visibility. @BeijingAir’s sense of humor, unfortunately, had been stripped.

With PM2.5 levels venturing into the unnamed stratospheric territories, he murmured to his loyal Twitter followers a much more politic descriptor: "Beyond Index."

Drilling rigs in California’s Central Valley, an area with some of the worst air quality in the nation. Earthjustice’s California Regional office is involved in litigation to improve the severe rates of air pollution. (Chris Jordan-Bloch / Earthjustice)

More Reads:

• "Beijing’s hazardous blue sky", China Dialogue
• "Clean Air A ‘Luxury’ In Beijing’s Pollution Zone", NPR (audio)
• "China Air-Quality Catastrophe—It’s Back", The Atlantic (video)