What Is in Vape Aerosol and How Toxic Is It?
Key takeaways
Health Canada says vaping liquids typically contain nicotine, propylene glycol, glycerol and flavouring chemicals, and that heating can create aldehydes such as formaldehyde, acrolein and acetaldehyde. Levels of harmful substances are significantly lower than in cigarette smoke, but long-term risks are unknown and nicotine is addictive.
Vape aerosol is not water vapour. Health Canada says it can expose users to chemicals that are harmful to health: nicotine, propylene glycol, glycerol, flavouring chemicals, aldehydes formed when the liquid is heated, and metal traces from the device. The department states that levels of some harmful substances are significantly lower than in cigarette smoke, and also that the long-term risks of inhaling these substances are unknown. This page summarizes Health Canada’s published position as of 27 October 2026.
What is in vape aerosol?
Vaping liquids typically contain four things, according to Health Canada:
- Nicotine. Most vaping substances sold in Canada contain it, and they can deliver more or less nicotine than a cigarette.
- Propylene glycol and
- glycerol (also called vegetable glycerin), the base liquids.
- Chemicals used for flavouring.
The device then adds more. At high temperatures propylene glycol and glycerol break apart into carbonyl compounds, also called aldehydes: acrolein, acetaldehyde and formaldehyde. Metal contaminants, including nickel and lead, may get into the aerosol as the metal heating element ages. Health Canada notes that some devices can produce more types and greater amounts of potentially harmful chemicals.
How does it compare with cigarette smoke?
Health Canada says some of these chemicals and metals are toxic and known to cause cancer, but “the levels found in vaping aerosol are significantly lower than those found in cigarette smoke.” Second-hand aerosol contains significantly fewer chemicals than second-hand smoke, and risks to bystanders are expected to be much lower.
Lower is not zero, and the department says so. Nicotine has been detected in the blood and urine of non-users exposed to second-hand aerosol, and there is some evidence that using e-cigarettes raises the level of nicotine and other chemicals on indoor surfaces. For the department’s wider comparison, including quitting, see harm reduction and snus and e-cigarette risks and benefits.
What does it do to the lungs?
Health Canada says vaping may cause lung damage by exposing people to chemicals like formaldehyde and acrolein, and that it can increase coughing and wheezing and intensify asthma symptoms in teens. The most common short-term effects reported are cough, nausea, headache, and throat and mouth irritation. Nicotine itself is not known to cause cancer or respiratory or vascular disease, but it causes physical dependence and addiction. For how smoke damages lungs by comparison, see smokers’ lungs.
What about popcorn lung?
“Vaping isn’t known to cause popcorn lung,” Health Canada states. Health Canada’s researchers found diacetyl in only 2 samples out of more than 800 vaping liquids, and there have been no confirmed cases of popcorn lung disease as a result of vaping in Canada.
What is not known?
The department is direct about the gaps. The long-term risks of inhaling these substances are unknown and continue to be researched. More research is needed to establish the health risks of long-term use, and Health Canada lists possible outcomes under study as cancer, respiratory disease and cardiovascular disease. For second-hand aerosol, variability in the chemicals between products makes exposure difficult to measure.
Cannabis vaping is a separate case: Health Canada says the aerosol can include harmful substances such as benzenes, and heavy metals may leach into concentrates and be inhaled.
How does Canadian law try to limit exposure?
- Nicotine cap. Every legal vaping product has a maximum nicotine concentration of 20 mg/mL.
- Labels. Ingredients must be listed in English and French, with nicotine concentration, a nicotine health warning and, for nicotine liquids, toxicity information and a hazard symbol.
- Child-resistant packaging for vaping devices, parts and nicotine liquids of 0.1 mg/mL or more.
- A hard ceiling. The Vaping Products Labelling and Packaging Regulations say a product must not contain nicotine at 66 mg/mL or more.
Rules for single-use devices in particular are in disposable vapes in Canada: legal rules, and the wider legal picture in vaping laws in Canada.
Health information is general and educational. It does not replace advice from a doctor, pharmacist or nurse. Read the full disclaimer.
Frequently asked questions
What chemicals are in vape aerosol?
Health Canada says vaping liquids typically contain nicotine, propylene glycol, glycerol and flavouring chemicals. At high temperatures the glycol and glycerol form carbonyl compounds (aldehydes) including acrolein, acetaldehyde and formaldehyde, and metals such as nickel and lead can enter the aerosol as the heating element ages.
Is vape aerosol as toxic as cigarette smoke?
Health Canada says some chemicals and metals in vaping aerosol are toxic and known to cause cancer, but the levels found are significantly lower than in cigarette smoke. It adds that long-term risks are unknown and still being researched.
Does vaping cause popcorn lung?
Health Canada says vaping is not known to cause popcorn lung. Its researchers found diacetyl in only 2 of more than 800 vaping liquids, and there have been no confirmed cases of the disease from vaping in Canada.
Sources
- Vaping: health risks — Health Canada. Accessed October 27, 2026.
- Vaping to quit smoking — Health Canada. Accessed October 27, 2026.
- Vaping product safety — Health Canada. Accessed October 27, 2026.
- Vaping Products Labelling and Packaging Regulations, SOR/2019-353 — Canada Gazette. Accessed October 27, 2026.