One of the clearest, most consistently documented relationships covered on this entire site.
Unlike many topics on this site where evidence is nuanced or still developing, smoking's relationship to chronic inflammation and disease risk is about as well-established as anything in medical research — smoking is a major, consistently documented driver of systemic inflammation.
Cigarette smoke introduces thousands of chemical compounds that trigger oxidative stress and sustained immune activation throughout the body, well beyond the lungs — contributing to the elevated cardiovascular, respiratory and metabolic disease risk consistently seen in smokers.
Vaping is newer, and long-term research is still developing, but early evidence points to vaping also triggering inflammatory and oxidative stress responses — it is not established as an inflammation-neutral alternative, even though it removes some of the combustion byproducts found in traditional cigarettes.
If you smoke or vape and want to quit, your doctor can point you to proven cessation support — this is one lifestyle change with an unusually strong, consistent evidence base behind its benefit.