Measurements of ozone were carried out at two different sites in the area s
urrounding a thermal power plant located in the Northwest of Spain during 1
993-1995. The concentration of O-3 in the ambient air varied from 6 to 257
mu g m(-3) exhibiting a wide temporal, seasonal and spatial variation. On a
few occasions 1-hr ozone concentration was more than 180 mu g m(-3), which
represents the maximum 1-hr limit of ozone in ambient air as prescribed by
the European Commission.