Creating a healthy indoor air environment means taking some small steps at home. In the cold winter months, some of us may open the garage door and turn on the car to warm it up. But even with the garage door open, exhaust can blow into your home and create an unhealthy environment. Instead, pull the car outside to let it warm up. Better yet, don't bother. Modern cars are designed with winter weather in mind, so turning it on and driving is enough to get the oil to circulate through the engine and have the car work efficiently.