Concentrations produced by an extended near-ground line-source of vehicularly-generated highway air pollution are considered with special emphasis on the influence of the obliquity of the wind. A result previously quoted by Turner is clarified, and it is shown that over a wide range of wind directions the concentration distribution can be calculated by a simple approximate formula. Although the concentrations increase as the wind more closely parallels the direction of the highway, the increase is only slight and for many practical purposes, could be disregarded.