Smog is mostly caused by cars. The best way to reduce smog is not to use cars as much as we normally do. But in reality, this is not a very prtactical solution. Ways to prevent smog are: 1. Combine your errands into one trip. Things will get done faster, and at the same time reduce traffic congestion and air pollution. FACT: After a car has been sitting for more than an hour it pollutes up to five times more than when the engine is warm. 2. Reducing your driving just once or twice a week, will reduce traffic congestion and pollution, and at the same time save you some money. 3. Vehicles on the road create more than 25% of all air pollution nationwide. 4. Walk or in-line skate instead of driving. These are easy ways to get exercise and they are easy on the air. 5. Keeping up with regular maintenance and tune-ups, changing the oil, and checking tire inflation can improve gas mileage, extend your car's life, and increase its resale value. 6. Refueling during cooler periods of the day or in the evening can prevent gas fumes from heating up and creating ozone. 7. Stopping short of a full tank is safer and reduces pollution. 8. Avoid using household products with high levels of volatile hazardous materials. Use electrical yard equipment instead of gas-powered. Do not use charcoal lighter fluid when you barbecue. Instead, use an electric starter or propane grill.