Tomorrow is National Trails Day and the Metro Parks Department is hosting a trail hike and trail construction in Jefferson Memorial Forest to encourage people to get outside. Unfortunately, Metro Government is warning people that the air could be dangerous for some.Matt Stull is the spokesman for the Louisville Metro Air Pollution Control District.“We’re seeing really some temperatures that are above normal,” he said. “You combine that with lack of cloud cover and also lack of wind and you see a buildup of ozone.”Stull is warning people with asthma, children and the elderly to stay inside during the afternoon and evening, as the ozone worsens. Everyone else is encouraged to avoid idling their vehicles and to combine errands into fewer trips.