From the International Herald Tribune:

... The State Environmental Protection Agency said that brisk economic growth and inadequate enforcement of environmental regulations were to blame for the "many outstanding challenges" hampering efforts to cut the country's air and water pollution.

In the first half of this year, the total national emissions of sulfur dioxide totaled 12.634 million tons, a decline of 0.88 percent compared with the same period last year...

Ahem, well, not exactly 12.634 million tons, it's actually twice as much.  Some governments like to play the media game of expressing emissions in terms of the weight component of the namesake element in the compound to make the numbers seem lower.  They report "emissions were x tons of something" and editors (who aren't very good with numbers anyway) almost always miss it and say "emissions were x tons of something dioxide" because that's the key molecule name almost universally used in reports.  So, 44 tons of Carbon Dioxide could be expressed (in this accurate but misleading way) as 12 tons of Carbon.  Likewise, 25.268 millions tons of Sulfur Dioxide (the actual number) is only 12.634 tons of Sulfur.

"We made some progress in our emissions control work, however, the situation is still grim,"

... "In the next half year, we will have to take more forceful measures to actively implement the policy and regulations," it said.

China had set a goal of cutting the emission of major pollutants by 10 percent in the five years to 2010. Last year, it failed to reduce the two main pollutants by 2 percent [and instead] Sulfur dioxide emissions increased 1.8 percent...

Sulfur Dioxide (SO2) is a compound mostly produced from the combustion of sulfur-containing "sour" fossil fuels, and in China that's mostly coal.  Though non-toxic to humans at low concentrations in food (it's used frequently as a preservative), hydrated aerosols of the compound in the air can cause respiratory illness and more famously, Acid Rain. 

SO2 emissions began to be regarded as problematic in the 1970's and action to reduce them significantly in developed nations began in the early 1980's with the advent of practical Flue-Gas-Desulfurization (FGD) technology.  FGD, at the expense of additional energy, cost, and carbon-emissions, runs power-plant exhaust through a slurry that trades the sulfur for carbon and turns limestone into Gypsum.  Gypsum is used for the building material Drywall, and regulations requiring FGD produced so much cheap "waste" Gypsum that much drywall made today is created by the process.  Not only that, but the low price encouraged builders to substitute drywall for many other materials and use it almost universally in new residential construction.

At it's peak in 1981, the US emitted about 23 million metric tons of SO2 into the air, but today, despite 26 years of economic growth and increased power consumption, emissions are nearly one third lower at around 15 million tons or 41,000 tons per day.  To put that in perspective, this tragic crime in June 2003, during the early months of the Iraq war, at the Al-Mishraq sulfur plant outside Mosul, caused a fire that released SO2 at more than half that rate!  One might ask, if it's so easy, why doesn't the US reduce it's SO2 emissions even further? The answer is that we no longer need to.  SO2 concentrations over almost all of the US are so low today that practically all harms have been eliminated and further reduction is unnecessary.  Under the rules of 1990 Clean Air Act, the US executed the first effective cap-and-trade system for emissions of SO2 in 1995, a system that has been so simultaneously effective and industry/economy friendly that it provides much inspiration for proposals to limit CO2.

China's emissions of SO2 (and CO2) are now the highest in the world, and higher than any other country has ever emitted.  In 2000, they reached 20 million tons, and despite some efforts at control they were 27% higher only five years later.  So the government said it would get tough, and even pledged that rates would drop a less-than-dramatic 2% a year to reach 23 million tons (in other words, return to 2003 levels) by the year 2010 (and even that level is high).  Given today's news, they probably aren't going to make it.

But all this begs the question - Why not?  FGD is a mature, well-developed, and relatively inexpensive technology. It has a proven effectiveness for over 30 years in a dozen nations.  Developed countries, and especially Japan (who experiences the brunt of China's unintentional international export of SO2 and Acid Rain), have made technology transfers and even offered to slightly offset the cost of retrofitting China's main emitting plants with the technology.  The problems associated with SO2 are serious, mostly local, and experienced in the immediate or short-term, and the government says it's a top priority.  Clearly though, environmental enforcement will not be allowed to get to the point that it could impede rapid economic development.

The reality of China's SO2 situation defeats assertions that "leadership" by developed countries by acting first to reduce CO2 emissions, even without binding commitments from emerging economies, will somehow encourage China to voluntarily follow in our footsteps.  Those that espouse these claims say that because of the magic motivational force of our "setting the example" we need not feel insecure about potentially shrinking our economies and undermining the competitiveness of our energy-intensive industries while China's unregulated emissions erase any contribution our sacrifices may have achieved.

But with SO2 we have set the example and demonstrated leadership for three decades.  China's motivation for reducing SO2 emissions is higher than for CO2 because while the magnitude of the harm is likely comparable, it is neither speculative nor an externality - almost all the damage occurs in their own country and is felt immediately.  It is within their own law that they must significantly reduce the concentration of this compound - and yet they do not control it effectively.  Given all this, upon what basic can one possibly suggest that they would be any better at controlling the emissions of a substance regulated by an international treaty?  And what reason can there be, when they avoid effective and cheap fixes, to expect them to sacrifice mightily in the absence of such a treaty?