Like a giant kid who's been holding a fart in during a three week elevator ride, Beijing has apparently relaxed its many industrial sphincters and let a big one rip. That's the only way I can explain the lighting-fast deterioration in air quality. In the space of about 36 hours the skies have transformed from the Olympic blue we all got perhaps just a bit too used to into standard northeastern industrial fug. Checking the SEPA website I was depressed to see that Beijing's air is actually worse than notorious air-pollution disaster areas Xian and Shijiazhuang. Payback's a bitch.

I knew it would happen, but it's depressing nevertheless. Yesterday morning I still managed a run even though the air was already silting up. Today it was all I could do to get out of bed and shuffle into the gym for some conspicuously non-aerobic exercises. Even so, I could feel my lungs calcifying while I lifted. A couple more weeks and it'll feel like I'm trying to breathe with two giant Brillo pads in my chest. The ones with the layer of cheap, pink soap on them.

Perhaps anticipating the change the in weather, my gym has installed two big IQAir filters. This should be a welcome addition given that, despite my best attempts to persuade myself otherwise, the air in the gym has always been as bad as the air outside, with haze visible in the spotlights during particularly grim days. On good air days the air in the gym is actually worse than the air outside, reeking of industrial carpeting, formaldehyde and burned plastic. Honestly, if not for the fact that during winter I can get from my apartment to the gym without ever stepping outside, I'd have given up on it long ago.

The problem with the filters is that the gym has exchanged one kind of pollution for another. One of the reasons why I like working out in the mornings is that the gym is quiet. There are no aerobics or spin classes filling the air with the shockingly loud THUMPA THUMPA THUMPA of bad dance music. The music coming out of the PA is quieter than in the evenings, and the girl at the counter is usually willing to turn it down when I ask.

This is good, because turning up my iPod to compete with ambient noise in the evenings had begun to damage my ears. Really. My standard first reply to anything my wife said had become, "Huh? What'd you say?" I had to switch to in-ear headphones to block more of the noise and enable me to keep the volume low enough that I wasn't caving in my eardrums.

Unfortunately, the IQAir filters in the gym are clearly comps. They're not free-standing, but rather embedded into large kiosks that contain brochures, which I don't mind, and LCD TV screens showing an IQAir marketing video, which I do mind. I mind it because the videos come with loud sound. Short of kicking the plug out, and thus turning off the filter, there seems to be no way to reduce the volume the level. This leaves me with a dilemma: Do I prefer lung cancer or deafness? Of course, you will recognize this as a false choice, with the likely actual outcome being deafness and lung cancer. But permit me my illusions.

At a stroke, I like my gym even less. I've also never been happier to be the owner of filters from IQAir's rival, BlueAir. If you're buying filters, remember: BlueAir. Their slogan: "We haven't fucked up Imagethief's gym with more ambient noise." If that's not reason enough to buy, I don't know what is.