PETALING JAYA, Sept 21 — Heated tobacco products (HTP) are often touted as less harmful alternatives to smoking cigarettes, but how exactly do they work?

Philip Morris International (PMI) recently held an Open Science webinar to break down the scientific differences between cigarette smoke and HTP aerosol, and why the heat-not-burn principle can help reduce certain risks for conventional cigarette users.

Check out the list below to learn more about their findings.

Aerosols are less complex than smoke

While cigarettes and HTPs produce a similar-looking cloud during use, it’s important to note that the emissions from the two products are not the same.

PMI’s lead of scientific and medical affairs Dr Markus Nordlund stated that cigarette smoke generated at high temperatures during combustion contains solid particles (soot), liquid droplets, and thousands of chemicals, 100 of which are recognised as harmful or potentially harmful by health authorities.

In contrast, an aerosol is formed during condensation or vaporisation and the composition can vary depending on the physical or thermal process that generates the aerosol.

Dr Nordlund said that aerosols are generally less complex than smoke with no solid particles and fewer chemicals.

"Smoke contains solid particles and thousands of chemicals that are generated at high temperatures when a material combusts.

"An aerosol that is formed at lower temperatures from vaporisation or condensation is much less complex than cigarette smoke and no solid particles are generated.

"This is why it’s so important for smoke-free products to avoid combustion, as it’s combustion that generates smoke,” said Dr Nordlund.

HTPs reduce levels of toxicants by over 90 per cent through the elimination of combustion

According to PMI’s global head of professional channels Dr Tom McGrath, a tobacco heating system produces aerosol with 90 to 95 per cent lower levels of harmful and potentially harmful constituents compared to cigarette smoke.

This is achieved by eliminating combustion in HTPs which raise the temperature of tobacco sufficiently to release nicotine and flavours without allowing combustion to occur.

"Scientific studies have shown that as the temperature of the tobacco increases, the levels of harmful and potentially harmful constituents also increase. 

"So, by eliminating combustion and reducing the temperature that the tobacco is heated to, we will significantly reduce the overall levels of harmful and potentially harmful constituents,” said Dr McGrath.

By heating tobacco instead of burning it, HTPs release significantly lower levels of toxicants to users. — AFP pic

HTP aerosol is less harmful, but not completely risk-free

Consumers should note that while HTP aerosol may contain lower levels of certain toxicants compared to cigarette smoke, it is not entirely risk-free.

HTPs are known as reduced-risk products, which present, are likely to present, or have the potential to present less risk to smokers who would otherwise continue using conventional cigarettes.

A targeted screening process of HTP aerosol found a 90 to 95 per cent reduction of 93 toxicants outlined by the United States’ Food and Drug Administration (FDA).

Similar results were also observed when HTP aerosol was screened for nine priority toxicants which are mandated for reduction in cigarette smoke by the World Health Organisation.

PMI’s project management and knowledge integration head Mark Bentley added that untargeted screening is also carried out on HTP aerosol to look out for the possible formation of other toxicants during the heating process.

"We are looking for everything present within the matrix and we don’t exclude anything at all. 

"We apply multiple analytical methods that are complementary and they have been designed to cover the entire chemical space associated with cigarette smoke and heated tobacco aerosol,” said Bentley.

Untargeted screening found 51 compounds which are higher in HTP aerosol compared to cigarette smoke and three compounds which are unique to HTP aerosol alone.

A toxicological evaluation by PMI concluded that the levels of these compounds do not present any additional risks compared to cigarette smoke.

Independent study shows HTPs can increase the life expectancy of smokers

A study published in May 2020 by the Dutch National Institute for Public Health and the Environment found that smokers who switched over to HTPs from cigarettes would be associated with a substantial increase in life expectancy compared to continued smoking for a subgroup of smokers who would die from cancer.

The study also states that the risk reduction would be most impactful in habitual smokers who switch over to smoke-free alternatives at a young age.

However, HTP users should still expect reduced life expectancy compared to non-smokers as total abstinence is the only way of eliminating all risks associated with tobacco use.