Firstly, public transportation is the best solution because it is reliable. Many people set up carpools to reduce traffic, but this is only a temporary solution. Every time someone has a change in their schedule, the carpool needs to be adjusted. For example, if someone has to go to the doctor or sleeps in, the carpool will not work that day. If someone changes jobs or transfers to a new school, the carpool will need to be adjusted again. Using public transport instead of cars, the air pollution problem can be mitigated quite effectively. On the other hand, One major downside of public transport systems is that the quality of those transportation systems is quite bad in many regions all over the world.