The global ozone budget has been studied in detail by Junge and one of his conclusions was that further systematic measurements of surface ozone at a number of sites over the globe would be of great value in consideration of stratospheric-tropospheric exchange processes. Such studies could provide information about where and when stratospheric air reaches the lower troposphere; the vertical mixing in the lowest 1.5 to 2 km during the day essentially provides a short-circuit between the surface and 1.5 km. Combined with ozone sounding data such as that gathered over North America, it is not unreasonable to hope that eventually the quantity of stratospheric air passing into the troposphere can be estimated. An objection often raised to Junge's proposed network of surface ozone stations is that measurements made near a city can be contaminated with ozone produced locally by the action of sunlight on automobile and industrial exhausts. There is some direct evidence of such production in the controlled experiments of Ripperton and in the existence of high ozone values in the polluted air of a relatively unventilated city like Los Angeles. This may account for the fact that the only surface ozone measurements added to the literature sincemore » Junge's paper are apparently those from the Antarctic reported by Aldaz. Thus, the question of the feasibility of the network suggested by Junge has not really been decided. In view of our interest in the general circulation of ozone in the atmosphere and its possible use as a tracer of the vertical transfer of energy from the troposphere to the stratosphere, we decided to monitor surface ozone in the relatively well-ventilated region of Greater Boston. This note represents the gross results for a one-year period.« less