Graculus writes with news about a plan to install sensors to collect environmental data and count people in Chicago. Chicago plans to install sensors in light poles to observe air quality, light intensity, sound volume, heat, precipitation, and wind. The sensors will also count people by observing cell phone traffic. The curled metal fixtures set to go up on a handful of Michigan Avenue light poles later this summer may look like delicate pieces of sculpture, but researchers say they'll provide a big step forward in the way Chicago understands itself by observing the city's people and surroundings. Some experts caution that efforts like the one launching here to collect data from people and their surroundings pose concerns of a Big Brother intrusion into personal privacy. In particular, sensors collecting cell phone data make privacy proponents nervous. But computer scientist Charlie Catlett said the planners have taken precautions to design their sensors to observe mobile devices and count contact with the signal rather than record the digital address of every device.