ScienceDaily: The London fog episode of the 1950s and the thousands of premature deaths that followed catalysed a series of attempts to improve air quality. According to author Philip K. Hopke, there have been continued efforts to determine sources of air pollution over the last 50 years. Moreover, according to a recent paper published in Journal of the Air & Waste Management Association (JA&WMA), developments in pollutant-measurement technologies continue to improve today. According to Hopke, the most effective...