If you care about the environment, I can see the appeal. At CES, the team showed me the various LED combinations you can trigger with a small dimpled button on the front. Different colors clearly indicate the quality of the air around you; a second button press gives you an overview of the day, with each tiny light representing a one- or two-hour block.

Flow works best when lots of people are using their devices simultaneously. Plume Labs will be collecting and comparing user data to create accurate, real-time pollution maps. The result will be an ever-evolving heat map with defined routes to avoid and clean, picturesque spots to enjoy. Swiping through the Flow's companion app, I was able to tap on starred parks that had been logged as pollution-free zones. The challenge will be persuading users to take potentially longer routes around their city or hometown. If you're running late for work, for instance, would you still accept a detour to avoid a patch of smog?

I care about my health, but I'm not sure I care that much. Unfortunately for Plume Labs, I suspect many people feel the same way. That's a problem, because scale will be critical in order for it to realize its crowdsourced air-mapping dream. Still, it's a noble goal, and one that I can't help but admire. Flow's success will ultimately depend on its pricing -- if the sensor is cheap, curious souls might be willing to give it a try. If it's expensive, however, only the most-green-thumbed individuals will take the plunge.

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