Smoking: frequently asked questions

What’s in a cigarette. The difference between mild and standard cigarettes. The effects of passive smoking, smoking during pregnancy, and much more. Here are the answers to some common questions about smoking.

Why is there so much emphasis on the dangers of smoking?

According to the World Health Organization (WHO), cigarette smoking is the leading cause of preventable death in our society: more than 8 million people die each year worldwide due to tobacco, including 1.2 million non-smokers who become ill as a result of passive smoking. The WHO also states that around 80 percent of the world’s 1.3 billion smokers live in low- and middle-income countries, and so smoking contributes to aggravating any health problems related to the scarcity of economic resources.

On the basis of data collected by the Italian Ministry of Health, approximately 93,000 people die as a result of cigarettes in Italy each year. In 2023, 20.5 percent of the people living in Italy were smokers - that’s one in five - and the 2023 statement by the Istituto Superiore di Sanità (ISS), noted that there were almost two million fewer smokers in Italy compared to the previous year. This is in contrast to the gradual increase over the previous ten years, which peaked in 2022, following the pandemic. However, although there are fewer smokers, those who don’t quit are smoking more: the average number of cigarettes per day has risen from 11.5 to 12.2, while a quarter of smokers exceed 20 cigarettes every day. The widespread uptake among young people is also of great concern. Statistics show that 9.6 percent of 11- to 13-year-olds and 36.6 percent of 14- to 17-year-olds smoke at least once a month, with a clear preference for e-cigarettes and heated tobacco products.

The ISS estimates that smoking tobacco is the single biggest risk factor for people’s health. This habit is responsible in Italy alone for about 43,000 cancer deaths each year, and 20.6 percent of all deaths among men and 7.9 percent among women. It causes more deaths than alcohol, AIDS, drugs, traffic accidents, homicides and suicides combined.

Multiple scientific studies have demonstrated that tobacco smokers are at greater risk than others of developing at least 27 groups of disease types, not just cancer, and this number increases to over 50 when considered in all their ramifications. Smoking increases the risk of dying from emphysema by about 10 times, doubles the risk of having a stroke and increases the risk of having a heart attack by two to four times, it damages blood supply to the brain and limbs and can promote erectile dysfunction in men. Overall, according to the WHO, tobacco kills about half of its users.

The carcinogenic substances found in cigarette smoke favour the development of lung cancer, which in 9 out of 10 cases can be traced back to this unhealthy habit; and it also stimulates cancers of the mouth and throat, pancreas, colon, bladder, kidney, oesophagus, breast - especially among younger women, and certain kinds of leukaemia, to varying degrees. The economic impact of smoking should not be overlooked either: in 2012 alone, the WHO estimated it had cost USD 422 billion, which is about 5.7 percent of total health expenditure worldwide.


What is inhaled with cigarette smoke? How do the substances in smoke favour the development of cancer?

Every time you light up a cigarette, you inhale more than 4,000 chemicals, at least eighty of which, according to the International Agency for Research on Cancer (IARC), are also carcinogenic. With each puff you inhale:

  • carbon monoxide, the same poisonous gas found in exhaust fumes from vehicles and heaters; it prevents oxygen from binding to haemoglobin and consequently causes cardiovascular damage;
  • nicotine, which is responsible for the effects of smoking on the brain and therefore also for physical addiction;
  • tar, which contains lots of carcinogenic substances, such as benzopyrene and other aromatic hydrocarbons;
  • acetone, like nail polish remover;
  • ammonia;
  • arsenic;
  • formaldehyde;
  • hydrogen cyanide;
  • nitrosamines;
  • radioactive substances, and much more.

The most carcinogenic substances in cigarette smoke are thought to be 1,3-butadiene, arsenic, benzene, and cadmium. Although the first is less potent than other substances, it is considered the most significant because it is present in cigarette smoke in large quantities; arsenic is also particularly dangerous, because it tends to accumulate in the body and interferes with our ability to repair DNA damage; benzene is responsible for a significant proportion (between 10 and 50 percent) of the kinds of leukaemia caused by smoking; and the amount of cadmium ingested when smoking exceeds the body’s ability to neutralise its toxicity.

Among the radioactive substances present, polonium 210 is especially significant. An analysis of the radioactive polonium content found in various cigarettes brands available in Italy has shown that in a year, on average, those who smoke about one pack a day run the same biological risk as if they underwent 25 chest X-rays. This radioactive substance is deposited in the lungs, exposing them to massive doses of high-energy radiation that can potentially trigger cancer-related genetic mutations.

Like radiation, many of the chemicals found in cigarette tar also damage the DNA in cells, causing mutations that can prompt uncontrolled growth. For example, benzopyrene, one of the most well-studied polycyclic aromatic hydrocarbons, tends to disrupt the gene that encodes the p53 protein, one of the most important molecules preventing mutations and thus protecting the body from cancer.

The negative effects of these substances intensify when they are absorbed all together, which is what happens when cigarette smoke is inhaled. One example of this synergistic effect occurs with chromium: it acts like a glue, making other carcinogens bond more firmly to the DNA, favouring the mutations they can cause. Other examples are arsenic and nickel, which interfere with the DNA repair mechanisms that correct errors as they occur. This is how the interactions between the different substances can amplify the damage caused to human genetic material.

The carcinogens contained in tobacco smoke may also indirectly facilitate the development of cancer. For example, by hindering the mechanisms which remove other toxins, like ammonia and hydrogen cyanide which destroy the cilia (hair-like structures) that line and protect the airways, or by blocking the enzymes that transform toxins into less dangerous substances, which is what cadmium does.

How many cigarettes can safely be smoked a day?

There is no safe level of smoking, below which it is harmless, not least because the consequences tend to accumulate over time. This is why research into the link between smoking and various diseases uses the “pack-year” as a unit of measurement, which takes into account the number of cigarettes smoked on average each day as well as how long the person has been smoking. In other words, smoking half a pack a day for two years is equivalent to smoking a whole pack for one year.

The mutations caused by carcinogens also accumulate, but each mutation occurs randomly. This means that the risk increases over the years as the mutations build up, but the time it takes for a healthy cell to turn into a cancerous one is not entirely predictable. It has been calculated that, on average, at least one mutation occurs for every 15 cigarettes smoked, and that consuming one pack a day for a year can result in around 150 mutations. In other words, every time a new pack is opened, it is like playing Russian roulette. By smoking persistently, however, the risks turn into almost inevitable consequences.

This does not mean that all smokers will develop cancer, nor does it mean that the disease cannot occur in people who have never put a cigarette in their mouth. There are many other factors, whether hereditary or environmental, which may contribute to protecting a person or to facilitating the formation of a tumour. One thing is certain: not smoking, or quitting, is one of the most important steps anyone can take to reduce the risk of developing a form of this disease.

Don’t fall into the trap of believing that an otherwise healthy lifestyle - eating plenty of fruit and vegetables or exercising regularly - will be enough to compensate for the damage caused by cigarettes. None of these factors carry the same weight as smoking, however useful they may be for our wellbeing and in preventing disease.

Starting to reduce the number of cigarettes per day can be a way to get used to the idea of quitting, but this has to be the first step towards breaking the habit for good. Those who just smoke a bit less quickly go back to their original amounts as soon as they find themselves in a stressful situation.

Is it better to choose mild cigarettes? Are pipes and cigars less harmful?

The terms light, mild, or low tar refer to the amount of tar in the cigarette. However, this is a misleading definition invented by the tobacco industry to lead smokers to believe that these products are less harmful. The differences between mild and standard cigarettes are actually minimal, and irrelevant in terms of their effects on the health of smokers. The belief that they are less hazardous may instead encourage people to smoke more and, above all, reduce the likelihood that smokers will decide to quit. What’s worse, scientific research has demonstrated that smokers using so-called mild cigarettes inhale more deeply and for longer. Consequently, the concentration of toxic substances in their blood is not lower than that found in smokers of regular strength cigarettes, nor does their risk of becoming ill over time appear to be lower. The findings of a study presented in 2019 at the annual congress of the American Thoracic Society show that there is no difference in the incidence of lung cancer between smokers of light and ultralight cigarettes, and smokers of standard cigarettes.

This is why the European Union in 2003, and the US Food and Drug Administration (FDA) in 2010, ordered the removal of the terms and definitions “mild”, “light” or “low tar” from cigarette packaging, as they are misleading for consumers. Studies conducted after these measures were introduced, however, showed that although these terms were not explicitly stated on the packs, smokers tended to think that wording such as gold or silver, or packaging with lighter colours corresponded to less harmful cigarettes. This led many countries to decide to market cigarettes in standardised packaging, whatever the strength, to make them less appealing. In Australia, for example, this law was passed in 2012; while in Italy cigarette packs have carried combined warnings (text and pictures) of the effects of smoking on health since 2016.

So, mild cigarettes are not healthier, but neither are cigars and pipes safe alternatives, even if users inhale the smoke less deeply. This slightly reduces the risk of lung cancer compared to cigarette smokers, but the odds of developing the disease are still much higher than among non-smokers. Cigar and pipe smoking also contributes to the development of cancer of the mouth, throat, oesophagus, and other organs such as the pancreas.

What is inhaled with the so-called e-cigarette?

The term electronic cigarette (usually abbreviated to e-cigarette, or e-cig, or vape) refers to a device used to inhale vapour that can contain varying amounts of nicotine. This reaches the respiratory system without burning tobacco, which is one of the main causes of the damage associated with normal smoking. E-cigarettes typically contain between 6 and 20 mg of nicotine, in a mixture that also consists of water, propylene glycol, glycerol and other substances, including flavourings.

These are potentially harmful substances. Propylene glycol has been in use for a long time, it is better known as the theatrical smoke in special effects for film and live entertainment, it is generally considered safe. However, some studies indicate that prolonged inhalation may irritate the airways, causing coughing, and in very rare cases asthma and rhinitis. Heating propylene glycol and glycerine can also produce formaldehyde and acetaldehyde, both potential carcinogens, although the quantities inhaled from e-cigarettes would seem to be low.

There is also a lack of data in scientific literature on the safety of the substances used to flavour these aerosol devices. For example, diacetyl, a flavouring widely used in butter, appears to be safe when ingested, but is associated with the onset of obliterative bronchiolitis (a rare condition that causes inflammation and narrowing of the airways) if it is inhaled over a long period of time in high concentrations.

According to the results of a study published in April 2017 in a journal of the American Physiology Society, there are approximately 7,000 different flavouring compounds contained in e-cigarettes that have not yet been studied in terms of carcinogenicity.

Like traditional cigarettes, e-cigarettes are a source of toxic metals, such as selenium, nickel, and aluminium, which are released during combustion at very high temperatures, around 1,000 °C. This is especially likely to happen if the e-cigarette is lit after the liquid has finished, this causes damage to the coil and, as a consequence, metals can leak out.

Are electronic cigarettes a safe alternative to smoking tobacco?

At present, e-cigarettes cannot be regarded as a safe alternative to tobacco products, neither for people trying to quit smoking nor for those who have never smoked before. Several recent studies have revealed that they can be extremely detrimental to users’ health, despite the fact that they are often considered harmless. This misperception is partly due to the fact that this type of product only entered the market recently – 2015 in Italy – and to the challenges associated with studying the effects of thousands of different flavourings. In 2019, a specific lung disease was linked to the use of e-cigarettes: “Electronic-cigarette or Vaping product use-Associated Lung Injury” or EVALI. This is caused by the release of toxic substances into the lungs, and the symptoms are shortness of breath, chest pain and coughing. However, further studies will be needed to establish the effects of e-cigarettes on the health and on cancer, taking into account the tens of thousands of products on the market, including the devices and liquids used in e-cigarettes. We have already reached the fifth generation of these products, which is completely different from the first, and this needs to be taken into due consideration.

Do e-cigarettes and heated tobacco products help to quit smoking?

On the basis of the scientific evidence gathered so far, the use of e-cigarettes and heated tobacco products to stop smoking is not recommended. According to the guidelines issued by the Istituto Superiore di Sanità (ISS) in Italy, these products “can in no way be considered a suitable tool for the purpose of beginning smoking cessation treatment”. This was also recently demonstrated by a prospective study led by Silvano Gallus, an epidemiologist at the Mario Negri Pharmacological Research Institute in Milan and supported by the Italian AIRC Foundation for Cancer Research. On studying more than 3,000 people in Italy aged between 18 and 74 over time, it emerged that electronic cigarettes and heated tobacco products not only do not help people to quit smoking traditional cigarettes, but they also actually encourage non-smokers and ex-smokers to start. The results of this study corroborate less recent data, such as the systematic review of the scientific literature on the topic, published in 2016 in the journal Lancet Respiratory Medicine, which found that smokers who use e-cigarettes are less likely to overcome nicotine addiction.

What are Heated Tobacco Products (HTP)?

Heated tobacco products or non-combusted cigarettes are electronic devices which, unlike e-cigarettes, are made with processed tobacco leaves. The WHO calls them Heated Tobacco Products or HTP, while the tobacco industry still tends to call them Heat-Not-Burn tobacco products, because the acronym HNB does not have the T for tobacco.

This kind of cigarette is inserted into a special electric burner which heats it to a high temperature (around 350 °C compared to 900 °C for traditional cigarettes), but it does not burn directly. These products have been developed by the tobacco industry and are sold under various trade names.

The vapour generated by heating the cigarette contains the same chemical components as traditional cigarettes, such as nicotine, benzene, and various kinds of particulate matter; while the concentrations are lower, they can still be risky. These products also contain other toxic or potentially harmful substances that are not found in traditional cigarettes, and their potentially detrimental effects on the health of users are still unknown and are being studied.

What is the impact of heated tobacco products (HTP) on the health?

According to the WHO information sheet issued in 2020, “Currently, there is no evidence to demonstrate that HTPs are less harmful than conventional tobacco products”. HTPs “contain chemicals not found in cigarette smoke and may have associated health effects”. Moreover, “more than 20 harmful and potentially harmful chemicals are significantly higher than in reference cigarette smoke” and “some of the toxicants found in the emissions of these products are carcinogens”.

Based again on WHO reports, although the temperatures reached by HTPs are lower than those of traditional cigarettes, toxic substances are still generated, some of which are not produced by conventional tobacco products. The effects of some of these on the health have been tested using laboratory animals and the results demonstrate that exposure to HTPs leads to a lower risk of developing cancer than conventional cigarette use, however, the odds increase as exposure increases. As for bystanders, scientific evidence is still scarce regarding second-hand emissions produced by HTPs, but the results so far suggest that the health risks are lower than with conventional cigarettes, but higher than with electronic cigarettes. Replacing traditional cigarettes with HTPs is therefore not a healthy choice, as both are toxic.

For the time being, there is a lack of sufficiently extensive, long-term studies to be in a position to understand all the health effects of HTPs; partly because there are so many substances to be assessed, and the effects may also manifest themselves after years of exposure. Current scientific evidence advises against using them, even by people who want to quit smoking traditional cigarettes.

What are the effects of passive smoking?

It has now been amply demonstrated that the detrimental effects of smoking also apply to people who live or work with one or more smokers and are therefore forced for years to breathe in both the smoke emitted after it has been inhaled (mainstream smoke), and the smoke released directly from cigarette combustion (sidestream smoke). This second-hand smoke increases the risk of developing lung cancer in non-smokers by at least 20 percent, as well as making them susceptible to heart disease, asthma, and other conditions. Every year, passive smoking kills about 1.2 million people, 65,000 of which are children under the age of 15 who die prematurely.

Passive smoking is particularly damaging to infants, from pregnancy to birth, and throughout their growth as the body continues to develop. Babies that are exposed to smoke are more at risk of what’s known as cot death or SIDS (sudden infant death syndrome) in the first year of their life. Even after this danger has passed, children living with smokers remain more vulnerable to lung infections and are at higher risk of developing asthma.

The risks associated with passive smoking apply to traditional cigarettes, e-cigarettes and devices that burn tobacco, both indoors and outdoors. Numerous scientific studies published over the past 20 years have shown that pollution in indoor environments such as homes, offices, and bars is more dangerous than outdoor pollution. This is because people generally spend much more time indoors than outdoors, and because in small, enclosed spaces there is a much higher concentration of gasses and dust from household pollutants, a key source of which can be cigarette smoke. There is also third-hand smoke, which refers to the toxic effect of substances released by tobacco combustion that can saturate indoor environments, in particular fabrics like clothing, curtains, carpets, bedspreads, armchairs, and sofas. There are far fewer studies on the carcinogenic effect of these toxins compared to those on passive smoking, however there is evidence that third-hand smoke can lead to cardiovascular disease and other problems for anyone regularly exposed to it, including children and pets, especially when this is in addition to exposure to direct and passive smoke.

Restrictions on the use of cigarettes are therefore crucial for everyone’s health. According to the 2021 WHO report, bans on smoking in public places have been effective in reducing premature births, asthma, and hospital admissions for respiratory tract infections. Based on this evidence, over the years many countries have implemented strict rules on smoking in public places and workplaces, some restrictions also extend to outdoor areas. Research conducted by the Pneumology Department of the National Cancer Institute in Milan has shown that concentrations of toxic substances due to smoking can be very significant even in outdoor venues, on the beach, or at football stadiums.

What are the consequences of smoking during pregnancy?

Many women stop smoking during pregnancy because they are aware that smoking is harmful to both their health and that of their unborn baby. Smoking reduces the oxygen supply to the foetus; what’s more, after the third month there is an increased likelihood of miscarriage and of the baby being underweight at birth, and there is a higher chance of the unborn baby developing other health problems. The consequences of smoking during pregnancy carry on after birth too: throughout the first year the child runs a higher risk of cot death, and in later years the child will be more susceptible to respiratory diseases such as asthma, as well as eye disorders like strabismus (crossed eyes) and retinopathy.

It is important that not only the mother carrying the baby but both parents avoid smoking during pregnancy and while the child is growing. Passive smoking can make children more likely to develop asthma, other respiratory problems, and heart disease. Just as importantly: the children of smokers are more likely to start smoking.

What’s the best way to quit smoking?

There isn't a one-size-fits-all way to quit smoking. This is because everyone’s reasons for smoking vary, as do their lifestyles, jobs, and their psychological and physical characteristics. The important thing is not to be discouraged by failure, and to remember that with each setback the chances of success increase.

There are several options for those who want to quit:

  • ask your doctor for advice on medication that can be prescribed, such as cytisine and bupropion that are designed to reduce addiction to cigarettes, or nicotine replacement therapy using patches and chewing gum, for example;
  • avoid e-cigarettes and heated tobacco products. Recent studies show that they can cause health problems and do not help smokers to quit, quite the opposite, they encourage people who don’t smoke traditional cigarettes to start.

If I have already developed cancer, what is the point of quitting?

Even people who already have cancer should quit. Several studies have demonstrated that giving up cigarettes is worth it because it improves the progression of the disease. Researchers from the University of Birmingham analysed the results of 10 studies and their findings were published in the British Medical Journal. Among the results, they showed that people diagnosed with lung cancer at an early stage can double their chances of survival by quitting smoking straight away.

Other research has established that smoking can increase the side effects of chemotherapy and radiotherapy and reduce their effectiveness, it also hinders healing after surgery and increases the risk of infections – mainly bronchopulmonary – which can be very dangerous in an organism debilitated by disease or with a suppressed immune system caused by the treatments they are undergoing.

Last but not least, continuing to smoke increases the risk that, once cured, the disease will return, or a second form of cancer will develop.

How does scientific research contribute to the fight against smoking?

If we are aware nowadays of the risks associated with smoking, it is in part thanks to scientific research, which has helped to demonstrate and describe the extent and the way in which this habit causes damage throughout the body, mainly in terms of cancer. This has made the public aware of the consequences of smoking and has obliged governments to take note of the enormous social impact of this problem. Over the years, various restrictive measures have ensued, from increasing taxes on cigarettes to banning smoking in public spaces and workplaces.

Research has also made it possible to identify ways both to help people quit smoking, for example by developing products that release nicotine as replacement therapy, and by devising psychological treatment programmes, as well as ways to treat the damage caused by smoking.

Blaming smokers is unhelpful: firstly, because the habit and the ensuing addiction are generally caused by a combination of environmental, behavioural, genetic, and hereditary factors, and they often reflect economic and social inequalities that have long been entrenched in society. Secondly, research into the prevention of smoking and its treatment benefits the entire community. For example, studies looking into the potential genetic predisposition to smoking help to enhance our understanding of the human genome and assess how it may affect our behaviour in a broader sense.

Optimising the treatment of smoking-related illnesses and improving prevention not only increase the quality of life of smokers, but also help to reduce the related expenditure faced by national health services and the enormous environmental impact of the tobacco industry.

Is there a such a thing as an inherited tendency to becoming addicted to smoking?

For many years, questions have been raised in the scientific community about a possible genetic susceptibility to nicotine addiction, and several studies seem to confirm this. According to the National Institute on Drug Abuse in the USA, between 40 and 75 percent of the risk of becoming addicted to nicotine comes from people’s genetic characteristics. Some genes are directly associated with nicotine addiction, such as variants in the CHRNA5 gene, others affect the number of cigarettes consumed, the likelihood of quitting and the effectiveness of treatment. For example, an organism’s response to the nicotine replacement drug varenicline is associated with variants in the CHRNB2, CHRNA5 and CHRNA4 genes.

A recent study, the results of which were published in the journal Nature, carried out the most extensive investigation to date into the genetic predisposition to smoking and alcohol, revealing the presence of 3,500 DNA variants associated with these forms of addiction. The researchers analysed the genomes of 3.4 million people in Europe, Africa, East Asia and America, and applied Genome-Wide Association Study (GWAS) techniques, a computerised system which makes it possible to identify statistical correlations between hundreds of thousands of genetic variations and a specific trait or disease.

A great many complex investigations led the researchers to conclude that the presence of genes linked to habitual tobacco consumption is associated with addiction, disadvantaged financial circumstances, and the diagnosis of lung disease. Although these findings require further study, this investigation represents a promising starting point for the study of the human genome and of increasingly targeted and effective prevention systems. Identifying susceptible people in advance could prevent many smoking-related diseases and deaths.

This information does not substitute professional medical advice or consultations with healthcare professionals.