@article {11561,
	title = {Widespread Reductions in Haze across the United States from the Early 1990s through 2011},
	journal = {Atmospheric Environment},
	volume = {94},
	year = {2014},
	month = {May 27},
	pages = {671-679},
	publisher = {Elsevier},
	keywords = {Air pollution, Air quality},
	author = {Hand, Jennifer L and Schichtel, Bret A and Malm, William C and Copeland, S. and Molenar, J. V and Frank, N. and Pitchford, Marc L}
}
