Why is it that after dark the city is overrun with yellow garbage bags? —Kelley Walker, Riverdale

Here's the dirt. Now that our rubbish is being trucked to ultra-pricey landfills in rural Michigan’s garbage-friendly Sumpter Township, businesses are helping to pay the steep American rent. They're forking over a tidy $3.10 a pop for the certified canary yellow bags you've spotted piled gutterside after hours, and the city hopes to generate $3 million a year from this stringent program: no yellow bag, no pickup. The good news is, stinginess may force companies and restos to adopt a more environmentally friendly outlook. They can minimize yellow bag use by diverting organic matter to green bins (long-term fantasy: all garbage will be recyclable by 2010). Currently, 250 tons of rot is carted off every week to an anaerobic digestion facility in Downsview, where it's converted into methane. The city eventually plans to use the gas to cleanly generate electricity. Let's hope this green agenda doesn't meet its fate in a Glad Quick-Tie.

• Categories: Environment