After half a century from the first provisions on air pollution in Iranian cities in an amendment to the Municipal Act in 1967 and on the basis of experiences gained from 22-year enforcement of the Prevention of Air Pollution Act of 1995, Iranian legislative and executive branches passed the Clean Air Act in 2017. Although this Act has some weaknesses, but its strengths, in particular improvement of criminal provisions and its innovations compared to the Prevention of Air Pollution Act, have created the hope that by enforcing it, the catastrophic situation of air pollution would be resolved. The most important improvements of criminal provisions in this Act are: 1. increasing criminal liability of juristic persons, 2. coherence of punishments, 3. anticipating modification of fines, 4. Increasing punishments. The most important innovations of it also are: 1. using the economic tools, 2. renovation of motor vehicles, 3. sampling and monitoring of pollutants by industrial units, 4. production and supply of renewable and clean energies, 5. increasing the green space of cities, 6. combat dust phenomenon, 7. granting the position of sheriff's officer to the protection unit of Department of Environment, and 8. providing specialized courts in the field of air pollution.