As the media spotlight continues to shine a light on air pollution across the planet, nations and communities are employing lots of innovative approaches to try to ameliorate their air quality problems.  Sometimes these approaches work beautifully; and sometimes they don’t.  But our ability to assess these approaches can be constrained by an important lack of quantitative data that captures the real-world effects.  Our group at UMass is trying to work with these communities, and we think there is a real opportunity for small sensors to be really quite informative.    Dr. Pallavi Pant, of the University of Massachusetts, writes an important piece on New Delhi , India.