How does smoking relate to risk of heart attack and atherosclerosis

Smoking is a dangerous habit that increases the risk of heart attack and atherosclerosis. The toxins in a cigarette can lower a person’s “good cholesterol” while lowering their “bad cholesterol.” The nicotine and carbon found in a cigarette can also harm the endothelium. Aside from this, it increases the chances of developing malignant hypertension. Smoking is indeed bad for the heart. 

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.