Putting waste products to good use seems to be something of a trend at Heineken. For New Zealand's DB Export beer brand, Heineken and Colenso BBDO made biofuel out of leftover brewing yeast, leading to a Cannes Grand Prix win, among other things.

Now another brand in Heineken's stable, Singapore's Tiger Beer, is turning air pollution into ink. The brand worked on the project with Marcel Sydney and Graviky Labs, an Indian startup and spinoff of MIT Media Lab.

The team put contraptions to collect pollution on the exhaust pipes of trucks, ferries, chimneys and cranes in Hong Kong and India. About 40 gallons of ink came out of it, the equivalent of 2,500 hours of diesel car emissions. Asian street artists Bao Ho, Caratoes, Xeme and Kristopher H used it to paint murals and ads in Hong Kong.

The social consciousness and street art jibe with Tiger's efforts to cast the historic brand as young, relevant and edgy, even if the link between air pollution and beer seems tenuous. Here's how the brand rationalizes the connection: "The streets are not only a great place to drink Tiger, they're also the place where creativity, ideas and passion are born," Mie-Leng Wong, director of international brands at Tiger Beer, Heineken Asia Pacific, said in a release. The brand is planning similar efforts across Asia next year.