Louisville’s Air Pollution Control District has called an Air Quality Alert for this weekend.The alerts this weekend are the ninth and tenth times this year the Air Pollution Control District has forecasted that ozone levels will be unhealthy for sensitive groups. But the alerts are forecasts—and the actual air quality has only been unhealthy twice so far.District spokesman Tom Nord says a mix of pollution and weather contribute to the poor air.“It’s a combination of high pressure and hot, stagnant air just kind of settling over the area,” he said. “That’s pretty typical this time of year. We’re counting on a front to come through on Sunday that will push a lot of this air out and bring things back to the normal, more healthy range.”There was already one Air Quality Alert this week—on Wednesday. But ozone levels turned out to be normal. This weekend, ozone levels are predicted to be unhealthy for the elderly, the young and those with heart and lung conditions.