Cigarette Smoke Chemicals and Health Risks: The Specific Effects of Smoking on the Body

Cigarettes have long been consumed as a symbol of independence, freedom, sophistication and charm. However, if you look at each ingredient in the smoke, it becomes clear how large and specific the price the body pays for this symbol is.

◇ List of chemicals in smoke

Cigarette smoke contains over 50 substances known to cause cancer. Representative examples include acetone and ammonia, arsenic and formaldehyde, cyanide and methanol, naphthalene and phenol, polonium-210, urethane and vinyl chloride, benzene and lead, nickel and mercury, cadmium and tar, and carbon monoxide. Cigarette smoke as a whole contains 7,000 types of chemicals, of which dozens are classified as Group 1 carcinogens. It is also a little-known fact that not only the mainstream smoke that the smoker inhales, but also the sidestream smoke that spreads into the air as the cigarette burns contains a higher concentration of harmful substances.

Among these, key hazardous substances are condensed into a few categories. Nicotine reaches the brain about 10 seconds after inhalation and stimulates the secretion of dopamine in the reward circuit, and as this process is repeated, it creates strong dependence. Tar is a black-brown mucilage that is a complex of over 2,000 types of chemicals, many of which have been identified as carcinogens and are considered a key cause of lung cancer.

The tar that sticks to the lung tissue deposits black wherever cigarette smoke passes, and it is this substance that appears covered in black spots when the lungs of long-term smokers are dissected. Carbon monoxide binds to hemoglobin nearly 100 times better than oxygen, reducing the oxygen carrying capacity of blood, which leads to chronic hypoxia and premature aging. Benzopyrene is a carcinogen created during the incomplete combustion of fossil fuels, and is also present in charcoal-grilled food and automobile exhaust gases.

◇ Numbers engraved on the body

The diseases caused by smoking are widespread. Representative examples include heart attack and stroke, chronic obstructive pulmonary disease, lung cancer, oral and pharyngeal cancer, larynx and bladder cancer, pancreatic cancer, peripheral vascular disease, and high blood pressure. According to the evidence behind the production of smoking warning pictures, 80-90% of lung cancer, 80% of larynx cancer, and approximately 50% of oral cancer are directly related to smoking. There are reports that smoking in pregnant women increases the risk of premature birth, low birth weight, and sudden infant death syndrome, and in men, the risk of erectile dysfunction increases significantly compared to non-smokers. There are also studies showing that the infertility rate among women is higher than that of non-smoking women, and the miscarriage rate also rises significantly.

The relationship between smoking amount and disease occurrence is consistently confirmed in several studies. In a domestic survey, the incidence of lung cancer among men who smoked more than 20 cigarettes a day was 6 times higher than that of non-smokers, and for those who smoked 40 or more cigarettes, it was 12.6 times higher. Another study reported that the risk increased up to 100 times when smoking more than 40 cigarettes a day. Although there are differences in each survey due to different target groups and observation periods, the conclusion is the same: the risk increases steeply as the amount of smoking increases.

It is also commonly pointed out that the risk is particularly high if you start smoking during adolescence when your lungs are not fully developed. On the contrary, there is also a large-scale domestic follow-up study showing that just reducing smoking by 10 or more cigarettes a day reduces the risk of lung cancer by about 45%, which is cited as evidence that reducing smoking itself is meaningful even if it is difficult to completely quit smoking.

The damage caused by secondhand smoke is not light. There is a study that shows that children who grow up in homes where both parents smoke have a 72% increased risk of respiratory disease and a 37% increased risk of developing asthma. More than 4,000 chemicals have been identified in secondhand smoke smoke, and the World Health Organization (WHO) states that there is no safe exposure level. Recently, the problem of 'third-hand smoke', in which harmful substances remain on the surface of carpets, clothes, and wallpaper even after the cigarette smoke disappears and are later absorbed, is also receiving new attention.

◇ Smoking status and social costs in Korea

According to the Korea Disease Control and Prevention Agency, the number of deaths due to direct smoking in Korea as of 2022 is 72,689, accounting for 19.5% of all deaths. The number is increasing every year from 61,360 in 2020 and 63,426 in 2021. The socioeconomic cost amounts to 13.6316 trillion won, and this figure does not include damage caused by second-hand smoke. WHO announced that more than 8 million people worldwide die every year from smoking, of which 7 million are due to direct smoking and approximately 1.2 million are due to passive smoking.

The domestic adult smoking rate is around 34% for men and 6.6% for women. The male smoking rate has fallen by nearly half from 66.3% in 1998, but the rate of decline has slowed since 2008, and the female smoking rate has not changed significantly for over 20 years. In 2015, when the price of cigarettes was raised by about 2,000 won and pictorial warnings were introduced on cigarette packs, the smoking rate dropped noticeably, but health authorities say it has since plateaued again. The smoking rate among Korean men still exceeds the OECD average.

Sigmund Freud, the founder of psychoanalysis, underwent nearly 30 surgeries for oral and jaw cancer after decades of love, and died in extreme pain. Even during the Joseon Dynasty, cigarette smoking was already a social problem. Hamel, who drifted to Jeju in the 17th century, recorded that the people of Joseon enjoyed smoking regardless of age or gender, and King Injo even issued a ban on smoking, which was a practice of his subjects smoking pipes. There is also a record that at that time, a pound of good tobacco was so valuable that it was traded for one nyang of silver.

Electronic cigarettes are devices that heat liquid containing nicotine and inhale it as an aerosol, which smokers often choose instead of quitting smoking. According to the WHO 2025 report, although the rate of traditional cigarette smoking is decreasing, the number of e-cigarette users has exceeded 100 million worldwide. The tobacco industry promotes the logic of 'harm reduction' that e-cigarettes are less harmful than regular cigarettes, but the health effects of long-term use have not yet been fully identified.

Heavy metals and toxic substances are detected depending on the product, and the issue of second-hand smoke and heavy metal exposure caused by electronic cigarettes is also a new research subject. In particular, reports that teenagers who start smoking with liquid e-cigarettes have up to three times higher odds of switching to regular cigarettes later lead to concerns that e-cigarettes may become a gateway to smoking rather than a gateway to quitting smoking.

◇ Reasons why it is difficult to quit

When talking about highly addictive substances, nicotine is often mentioned next to heroin and cocaine. It is known that 85% of smokers who try to quit smoking go back to smoking. This means that it is not easy to quit smoking through willpower alone, and it also means that systematic support is needed, including smoking cessation clinics, alternative treatments such as nicotine patches and gum, and even drug treatment if necessary.

Fortunately, the body is resilient. A common trend shown by many follow-up studies is that blood pressure and pulse begin to return to the normal range within 20 minutes of quitting smoking, after one day, the concentration of carbon monoxide in the blood decreases significantly, and after one year, the risk of heart disease falls to half that of a smoker.

It takes more than 10 years for the risk of lung cancer to drop to the level of a non-smoker, but recovery begins immediately after quitting smoking.

Quitting smoking always takes the first place in the list of healthy lifestyle habits. The price of a cigarette should not be calculated as money paid at a convenience store, but as a 'bill' that both the body and household will receive later.

Eom Yung-ui, professor emeritus at Seoul National University College of Medicine

▲ Served as a professor in the Department of Physiology at Seoul National University College of Medicine ▲ Researcher at Oxford Medical School, UK, member of the British Physiological Society ▲ Chairman of the Cardiovascular Division, International Union of Physiological Sciences ▲ Deputy editor of the European Journal of Physiology ‘Plügers Ahip’ (current) ▲ Regular member of the Korean Academy of Medical Sciences (current) ▲ Daegu Gyeongbuk Institute of Science and Technology, Interdisciplinary Department, Biomedical Science Major, Invited Chair Professor (current)