IMPROVE Interagency Monitoring of Protected Visual Environments CIRA Cooperative Institute for Research in the Atmosphere CIRA Cooperative Institute for Research in the Atmosphere IMPROVE Spatial and Seasonal Patterns and Temporal Variability of Haze and its Constituents in the United States S p a t i a l a n d S e a s o n a l P a t t e r n s a n d T e m p o r a l V a r i a b i l i t y o f H a z e a n d i t s C o n s t i t u e n t s i n t h e U n i t e d S t a t e s ISSN 0737-5352-87 ISSN 0737-5352-87 Report V R e p o r t V June 2011 June 2011 Acadia NP 1990 1995 2000 2005 2010 Year 0 2 4 6 8 (µg/m ) 3 50 th Percentile PM 2.5