HealthDay News: More than three decades of data showing how clear, or unclear, the sky over land has been should reveal how changes in air pollution have affected climate change, according to a University of Maryland-led team of researchers. The data show that what the researchers call clear sky visibility over land has decreased worldwide since the early 1970s because of an increase in aerosols, which are solid particles or liquid droplets suspended in air. Aerosols, which include soot, dust and …