text: Along with greenhouse gases, smog is also another problem. Smog is a mixture of the fog and moisture in the air combined with exhaust from cars, smoke from cigarettes, and other toxic fumes. We have to have smog checks on our cars at least once a year to see if our vehicles are protected against the chemicals. Smog can be prevented somewhat by halting the use of vehicles. Also, if we don't use cars, not only will we have less smog, but we won't have to pay for the annual smog checks. We'll be helping our environment and helping our wallets.