Validate Personal Air-Pollution Sensors

The public is increasingly aware of the health and economic costs of air pollution. Poor air quality is linked to over three million deaths each year, and 96% of people in large cities are exposed to pollutant levels that are above recommended limits1. The costs of urban air pollution amount to 2% of gross domestic product in developed countries and 5% in developing countries (see go.nature.com/28qv0ka).