Constantly sold out in China where air pollution is a huge problem. One clever aspect is a network business model, "Furthermore, users of both apps will have access to a map function. Businesses that install a Laser Egg can upload their PM2.5 measurement in real time to the apps so users can look around them on the map for cafes, restaurants, and other places with clean air. The initiative is just getting off the ground, but co-founder Liam Bates says businesses have been extremely receptive to the idea. "For those that have invested already in air purifiers, they’ll spend a few hundred kuai extra and are able to tell everybody, show off that they have invested, and they do care about the air their customers are breathing. It’s really a no brainer for a lot of places," he says.