In short: Your alveoli all have blood supplies. It's the same mechanism that smoking damages your skin. Nicotine in your blood gets everywhere. It affects elas

In short: Your alveoli all have blood supplies. It's the same mechanism that smoking damages your skin. Nicotine in your blood gets everywhere. It affects elastin production throughout your body. Smoking is a multi-stage attack on alveoli. You're both physically damaging them with the smoke and inhibiting their ability to regenerate. But they're a high-use tissue. Even without the additional damage, you're harming their ability to regrow.