The work presented in this paper is part of a larger study whose objective it is to analyze the link between climate variability, air quality, and health over New York State and surrounding areas. The specific aims of the project are to: (1) develop fine-scale gridded maps of hourly surface weather, ozone, and particulate matter (PM) over New York State over the 15-year period 1988-2002 using observations integrated with simulations from a photochemical modeling system, (2) analyze the relationship between climate variability and episodes of extreme PM, ozone, and heat, and (3) measure the independent and joint effects of air quality and weather on acute mortality and hospitalization risks from 1988 to 2002.