@OP

"douchebag americans"

This is crude bigotry.

(Edit: added @)

OP reporting back just in case anyone ever has a similar problem. I couldn't find pure ammonia water anywhere, so I used the Mr. Muscle-brand blue window-washing liquid since it has ammonia as an active ingredient, and that got rid of the smell. I sprayed the clothes until they were saturated, let them sit for about five minutes, and then laundered them with regular detergent. (I didn't have any success with baking soda, and mixed results with color-safe bleach.)

You have to spray a lot of Mr. Muscle to saturate the clothes (dozens of pumps for larger garments vs. just a few to wash a window), and it can kick up enough of a mist for health and safety issues to be a concern, especially if you're using it in a closed space. So I would advise researching the ingredients and taking precautions accordingly. Also, I used it on dark fabrics, but I tested it on a white rag and it left a faint blue stain even after washing.

Other things FYI:

- The southern B&Q location (on Guan Nan Da Dao) is just a small showroom, not a full-sized store.

- Metro doesn't currently carry Oxiclean, at least not at the Guangfu Lu location.

Thanks to all for the advice and suggestions.

I have sealed up the offending clothes in a couple of the big airtight plastic storage bags they sell at Walmart & Carrefour, which seems to have worked for controlling the allergies until my next round of cleaning efforts.

@michael2015:

Soaking with baking soda sounds like a good idea -- I'll give that a try. As far as drying laundry, I fortunately haven't had mildew problems with clothes that I wear regularly, just with this batch that was in storage.

@tigertiger:

It's not especially dusty around my area -- I have lived here for a few years and no allergy problems until now

Thanks for the suggestions -- I appreciate it.

@michael2015: Although I didn't mention it in my original post, I really am aiming to eliminate the problem at the root. This is in part because I assume it's caused by a living organism that will continue to multiply if left unchecked, and also because it seems to be causing an allergic reaction (runny nose, sneezing) which probably would not be helped by dealing with the smell alone.

@dolphin: Yes, I did try exposure to sunlight, but without success.

Good to know, I will check at Metro. I'm leery of using bleach as most of the clothes are cotton in various colors -- I will try that as a last resort before throwing them away if nothing else works.