Characterization of offshore/onshore Lake Michigan air quality at shoreline in southeastern Wisconsin

Air quality in SE Wisconsin is currently under review for being removed from its designated non-attainment status for the federal 8-hour ozone standard. Kenosha County is one county of 3 in WI which was in non-attainment of the 8-hour average ozone standard for 2006-2008. The region along Lake Michigan is influenced by the local proximity of Chicago and Milwaukee and ozone production over Lake Michigan. The regional meteorological conditions produce events of easterly air flow (such as the Lake Breeze effect) which aids the onshore flow of Lake Michigan air masses. This study outlines the monitoring of O_{3}, NO_{2} and SO_{2} by DOAS (path-length 600m) alongside standard meteorological variables at the Kenosha Harbor in SE Wisconsin from June 2009-Oct 2009 to identify the characteristics of Lake Michigan air masses at shoreline. The offshore (defined by wind direction) air masses indicate a low NO_{x} regime, with average NO_{2} concentrations 3.2 ppb offshore and 7.1 ppb onshore. The Lake Michigan air masses contain higher ozone concentrations with average concentrations 34 ppb offshore and 21 ppb onshore. Included in this study are preliminary measurements of offshore ozone abundances using a portable personal ozone detector while sailing along the shores of Lake Michigan. The personal ozone detector observations show a gradient of increasing ozone abundance offshore within 2 miles of shore. Questions relating to the efficacy of land-based measurements at various distances from shoreline and attainment designations for regional air quality to assess possible exposure risks for recreation at shoreline (beachgoing) or off-shore (sailing and boating) will be discussed.