The question refers to ground-level ozone, which is a major air pollutant harmful to human health and vegetation. High concentrations of ground-level ozone indicate poor air quality. A "good" amount of ozone in ambient air is a low concentration. Air quality standards typically classify levels up to approximately 0.06 ppm (or 60 parts per billion, ppb) as good or satisfactory. Concentrations significantly higher than this are considered moderate, unhealthy, or very unhealthy.