How significant damage would 2 years of smoking do?

Smoking damage: 2 years of smoking can definitely cause damage to the cells in your lungs that move dust and bacteria out. These cells, also called cilia, become stunned as soon as you start smoking. Fortunately, the cilia can begin working again as soon as you stop smoking. The longer you smoke, the greater chance of emphysema or worse lung cancer. I would suggest stopping smoking.

Unknown: Lung disease from smoking is dependent on the amount of cigarettes smoked per day multiplied by the number of years of smoking. Your lungs are constantly working to dispel toxic substances. After one year of stopping, your lungs can return to normal, as if you did not smoke. It usually takes many years to develop lung cancer from smoking. The sooner you quit, the less chance of damage.