Extensive research has documented that elevated air pollution increases mortality and morbidity, with estimates reaching 8 million deaths per year. Many of the world's one billion urban poor face both high ambient concentrations and even higher transient peaks. Should government interventions...

This paper compares retrospective and prospective analyses of the effect of flip charts on test scores in rural Kenyan schools. Retrospective estimates that focus on subjects for which flip charts are used suggest that flip charts raise test scores by up to 20 percent of a standard deviation....