How long does tar take to disappear after quitting?

Several studies say 7 to 15 years for full elimination, but the bulk of the clean-up happens in the first two years.

With a CO breath tester (similar to a breathalyser). Available at tobacco specialists and some pharmacies. It is very motivating: you see the number drop from day one.

Are filters actually any use?

Very little. They hold back some of the visible particles, but not the carcinogenic compounds, which slip through. They were mostly designed to look protective.

And the shisha — what does it do?

Even more carbon monoxide (up to 50 times a cigarette per session) and more tar. The 'water filter' is a myth. See our dedicated article.

How do cigarette fine particles compare to air pollution?

While you smoke a single cigarette, you inhale more fine particles than you would in 30 minutes by the side of a busy boulevard at rush hour.

Tar, carbon monoxide, fine particles: who really does the damage in cigarette smoke?

Nicotine is what hooks you, but tar, carbon monoxide and fine particles are what make you ill. Untangling who does what in tobacco smoke.

May 11, 2026 Aria

Nicotine is what keeps you hooked. But what makes you ill is something else — produced by the burning. Pulling the roles apart is the way to understand why vaping (no combustion) does far less damage, and why every single cigarette leaves a real mark on your body.

Who does what: three big families

1. Tar: the architect of cancers

Tar is the solid residue of incomplete combustion of tobacco. It sticks to the bronchial walls and unloads its most toxic carcinogens there:

70 confirmed carcinogenic substances in cigarette smoke. None in vaping (other than at marginal traces linked to manufacturing defects).

WHO / IARC, 2023

2. Carbon monoxide (CO): the silent suffocant

CO is a colourless and odourless gas produced by any incomplete combustion — including tobacco's. Once in your lungs, it does two serious things:

It binds to haemoglobin 200 times more strongly than oxygen. Your red cells start carrying CO instead of oxygen.
It forces the heart to work harder to compensate for the oxygen deficit, especially during exertion.

The result: poorly oxygenated tissues, early fatigue, accelerated atherosclerosis, raised cardiovascular risk from the very first cigarette of the day.

3. Fine and ultrafine particles: chronic inflammation

Cigarette smoke is also a soup of microscopic particles (PM2.5 and PM0.1 — even finer than urban pollution). These particles:

Reach deep into the alveoli, all the way into the bloodstream.
Trigger chronic inflammation in the airways.
Progressively destroy the alveoli (causing emphysema) and thicken the bronchi (causing chronic bronchitis).
Speed up atherosclerosis in the whole vascular system.

Chronic inflammation is the mother of all long-term damage: COPD, heart attacks, strokes, and a fertile ground for cancers.

And nicotine in all this?

Nicotine causes the addiction. But it is the tar and the carbon monoxide that cause the disease. Mixing the two up means missing the target when you try to reduce risk.

Selon les pneumologues

Myth vs reality

Why vaping changes the picture

No combustion, no tar. No carbon monoxide (or very little). Far fewer toxic fine particles. What remains is nicotine and a few aldehydes in small amounts. That is why UK agencies estimate vaping around 95 % less harmful than smoking — without saying it is harmless.

What your body does to defend itself — and why it eventually gives up

Your lungs have two natural lines of defence:

The cilia that push particles back towards the exit.
The alveolar macrophages, immune cells that swallow up intruders.

The acrolein and hydrogen cyanide in smoke paralyse the cilia from the very first puff. The macrophages get overwhelmed and end up damaged. Over time, the system grinds down — that is the smoker's cough, the first warning signal.

In United Kingdom

Your questions

How long does tar take to disappear after quitting?

Several studies say 7 to 15 years for full elimination, but the bulk of the clean-up happens in the first two years.
How is CO measured?

With a CO breath tester (similar to a breathalyser). Available at tobacco specialists and some pharmacies. It is very motivating: you see the number drop from day one.
Are filters actually any use?

Very little. They hold back some of the visible particles, but not the carcinogenic compounds, which slip through. They were mostly designed to look protective.
And the shisha — what does it do?

Even more carbon monoxide (up to 50 times a cigarette per session) and more tar. The 'water filter' is a myth. See our dedicated article.
How do cigarette fine particles compare to air pollution?

While you smoke a single cigarette, you inhale more fine particles than you would in 30 minutes by the side of a busy boulevard at rush hour.

sources

WHO / IARC, Tobacco smoke and involuntary smoking, IARC Monographs Vol. 83, 2004 and updates.
US Surgeon General, How Tobacco Smoke Causes Disease, 2010.
Anses (France), Tabac et substances chimiques, thematic dossiers.
Public Health England, E-cigarettes: an evidence update, 2015 and later updates.