IQOS and Secondhand Smoke: What We Know About Bystander Aerosol

When you use an IQOS device, the people near you breathe some of what you breathe out. There is no smoke, because nothing burns, but there is an aerosol, and it contains nicotine and other substances. The honest summary of the research is that bystander exposure is lower than with cigarette smoke but not zero, and nobody yet knows what years of it would mean. That is reason enough to treat it like smoke when other people are around.

Where bystander exposure comes from

A lit cigarette exposes people nearby in two ways: the smoke the smoker exhales, and the smoke that drifts off the burning tip between puffs. Heated tobacco doesn't burn, so there is no smouldering tip giving off smoke between puffs. That means bystander exposure comes mainly from what the user exhales.

That exhaled aerosol is mostly fine droplets and particles. It carries nicotine and some of the other substances found in the aerosol you inhale.

What studies have measured

Research on bystander exposure to heated tobacco is limited, much of it small, some of it funded by manufacturers. Without leaning too hard on any single study, a few consistent points come through:

1. Lower than cigarette smoke. Studies that compared heated tobacco with cigarettes in rooms or test chambers generally measured lower levels of nicotine, particles and other compounds in the air with heated tobacco.
2. Still measurable. Independent chamber studies, including work by researchers in Lithuania, found that heated tobacco had a smaller but still measurable effect on indoor air and bystander exposure.
3. Small spaces matter. A small 2020 study from Japan found that nicotine in the air built up markedly in a tiny, enclosed space after heated tobacco use, while levels stayed low in an ordinary-sized room. Room size and ventilation make a real difference.
4. Short-term, not long-term. These studies measure what is in the air during and after use. They don't tell us about health effects for people exposed regularly over years.

What isn't known

• Whether regular exposure to heated tobacco aerosol, for example living with a daily user, affects the health of the people around them over time.
• How exposure affects children, pregnant people and people with heart or lung conditions specifically.
• Whether results from older devices apply exactly to newer systems.

The World Health Organization's position is that heated tobacco products are harmful. Its 2020 statement notes that some toxins have been found at higher levels in heated tobacco aerosol than in cigarette smoke and that the health implications of these are unknown. Where the evidence is incomplete, the sensible assumption is caution.

Not zero: the rules worth following

Because exposure is not zero, the considerate approach is to treat your device exactly as you would a cigarette around other people.

• Follow no-smoking rules. Wherever smoking isn't allowed, don't use your device.
• Never around children. Not in the same room, not in the car with them, not while holding a baby.
• Never near pregnant people. Step well away, or wait.
• Ask before you use it near others. At home, at work, at a friend's place. Accept a no.
• Ventilate. If you use it indoors at home, open a window or step onto the balcony. Small closed spaces concentrate exposure.
• Never in a closed car with passengers. Our guide to using IQOS in the car covers this.

At home with family

Home is where bystander exposure adds up, because it happens every day. If you live with people who don't smoke, especially children or older relatives, the best habit is to use your device outside or on a balcony, never in bedrooms, and never in shared indoor spaces. Our guide to IQOS at home is practical about this, and the IQOS guide for Delhi looks at the pull to stay indoors during the winter smog season.

Less smell isn't less exposure

It's tempting to judge by the nose. Heated tobacco smells less and lingers less than smoke, so it feels like there's nothing there. That feeling isn't evidence. The aerosol is present whether or not people can smell it. Our guide to IQOS smell and ash is frank about what changes.

And for you

Everything above is about other people. For you, the user, heated tobacco is not risk-free, and TEREA contains nicotine, which is addictive. Lower exposure has not been shown to mean lower risk of disease. The best thing you can do, for yourself and for the people you live with, is to quit nicotine completely. Free help is on the National Tobacco Quit Line, 1800-112-356, and in our quit smoking guide.

Questions

Is there secondhand smoke from IQOS?

There is no smoke, because the tobacco isn't burned. But people nearby are exposed to the aerosol you exhale, which contains nicotine and other substances.

Is IQOS aerosol harmful to people around me?

Studies measure lower bystander exposure than with cigarette smoke, but not zero, and the long-term effects aren't known. Treat it like smoke around others.

Can I use IQOS around my children?

No. Keep your device away from children and use it outside, away from them.

Does opening a window help?

Ventilation lowers how much aerosol stays in the air, especially in small rooms. Using it outside is better still.