The spatial variation of the weekday/weekend differences in the Baltimore area.

This study examined the spatial distribution of the weekday/weekend difference in Baltimore, MD, and vicinity. The difference in Baltimore was characterized by having approximately 39% more NOx, approximately 59% more CO, and approximately 27% more volatile organic compounds (VOCs) on the average weekday, but there was approximately 13% more O3 on the weekend day. Spatially, the difference was elongated in the northeast-southwest direction. It decreased from 13% more O3 in Baltimore to 6% at approximately 20 km west of Baltimore and to 4% at approximately 40 km south of Baltimore. It also appeared to decrease to the east, but the magnitude of the decrease could not be determined because of the lack of data east of the Chesapeake Bay. However, the difference increased to the north, reaching a value of almost 18% at a northern Delaware site.