Department of State's air pollution sensors go global

In October 2010, as heavy smog hung over Beijing, the U.S. embassy9s Twitter feed reported that its rooftop air pollution sensor had detected "crazy bad" levels of hazardous microparticles. Fine particulate matter had shot up to about 550 micrograms per cubic meter—a level to which programmers had given the sardonic label because they thought it would never be reached. The undiplomatic language ruffled feathers in Beijing. Yet the incident and others like it spurred public complaints that eventually elicited more aggressive efforts to tame the pollution. By now, rooftop sensors like those that drew attention to Beijing9s pollution sprout from 26 diplomatic posts in 16 countries. Their immediate goal is to protect the health of U.S. citizens. But they are raising concerns about air pollution from Sarajevo to New Delhi and supplying data to research efforts.