There are many sources of environment pollution.The high way traffic is considered the main source of pollution of the environment. As the number of car is increasing and human daily use them. As the traffic increases the traffic increases as a result of gases sent by exhaust. The exhaust contains four kinds of poisonous gases such as carbon monoxide, hydrocarbon, nitrogen oxide and Sulphur dioxide. Carbon monoxide is considered which is a color less gas that has no smell or taste. It is poisonous. It is called silent murderer. The hydrocarbon causes effects such as eye pain and itch and dizzy cases. It causes troubles similar to wine effect. Also cancer and jeens change may happen inside the body. Diesel gas is formed of carbon particles. They are small particles.They are solid or liquid. They are found in the air. They have negative effect on respiratory system on human. They can pass through the muscus filter in the respiratory system. They penetrate the lungs. The danger of these oxides increase when it rains. As issues and security of environment are important. It is absolutely necessary to concentrate on them. Advanced countries and grown ones work hard to solve it. When the program of periodic checkup was executed in Saudi Arabia more than quarter of a century ago, the checkup of exhaust gases was the most important item. A stage was specialized for checkup of carbon monoxide, hydrocarbons and diesel gases. The schedule of the periodic checkup which was approved by his royal highness prince Naif bin Abdul Aziz vice prime minister and minister of interior confirmed its importance of solution. The program of The Kingdom's car technical checkup fortunately could advance good steps on the field of gases spread out of cars. That is a result of the developed equipment’s supplied to the program. It controls the allowed ratio of gases through measurements. The car would not pass the checkup if it sent more gases than the allowed ratio. It should be repaired and be returned for checkup once again. This program gave fine results. If the percentage of carbon monoxide is more than 4.5% and the hydrocarbons 1200 part per million and diesel gases density of carbon more than 50% the car would not pass checkup. For the purpose of air free of harmful exhaust the government would apply instructions according to international measurements for gases exhaust for all groups of cars. This application gave good results with buses for pilgrims transport. According to the rules the ratio of carbon monoxide would not exceed 2.5%, hydrocarbons 1200 part per million exhaust gases not more than 30%.