Smoking is one of the leading causes of preventable death and disease worldwide. The negative health effects of smoking are well documented. However, not all types of smoking carry the same risks. Some forms are more harmful than others. Determining which type of smoking is the most dangerous requires looking at the different products and methods used, as well as the associated health risks.
What makes smoking so harmful?
All forms of smoking expose users to toxins and carcinogens through the inhalation of smoke. Tobacco smoke contains over 7,000 chemicals, at least 70 of which are known to cause cancer [1]. Some of the most harmful components of tobacco smoke include:
- Tar – a sticky substance that contains thousands of chemicals, many of which are carcinogenic.
- Nicotine – the addictive chemical in tobacco that affects brain development and increases heart rate and blood pressure.
- Carbon monoxide – a toxic gas that reduces oxygen delivery to the body’s organs and tissues.
- Formaldehyde – a chemical used for embalming that’s known to cause cancer.
- Arsenic – a poisonous metal that can lead to cancer as well as cardiovascular and skin diseases.
When these substances enter the lungs through smoke inhalation, they can cause substantial cellular and DNA damage. Over time, this damage increases the risk of cancer significantly. Smoking has been linked to cancers of the lung, mouth, throat, bladder, pancreas, kidney, and more.
The particulates in tobacco smoke also irritate the airways and destroy cilia, tiny hair-like structures that help clear mucus and dirt from the lungs. This leads to chronic coughing, increased phlegm production, and frequent respiratory infections – all characteristic of chronic obstructive pulmonary disease (COPD).
In addition to cancer and lung disease, smoking raises the likelihood of cardiovascular conditions like heart attacks, strokes, and blood vessel disorders such as aneurysms. It also impairs immune function and hemeostasis throughout the body.
Combustible tobacco products
Any product that burns tobacco and produces smoke can be considered a combustible tobacco product. This category includes:
Cigarettes
Cigarettes are small paper tubes filled with shredded or processed tobacco. They are designed to be lit and smoked through inhalation. Many medical organizations consider cigarette smoking to be the most harmful form of tobacco use [2]. Cigarettes release a steady high dose of toxins due to the frequent inhaling required to smoke them.
A person who smokes a pack of cigarettes per day is exposed to 7,000+ chemicals at least 10 times [3]. These frequent toxin hits accumulate over time and make cigarette smokers extremely susceptible to chronic diseases.
According to the CDC, cigarettes are responsible for more than 480,000 deaths per year in the United States. That’s nearly one in five deaths annually [4].
Cigars
Cigars are larger tobacco rolls made of fermented and aged tobaccos. While cigars do no require inhalation in order to be smoked, many cigar smokers still inhale some of the smoke. As a result, they can absorb higher concentrations of toxins than cigarette smokers [5].
However, most cigar smokers do not smoke nearly as frequently as cigarette smokers. The overall dosing of toxins is lower.
One study found that smoking just 1-2 cigars per day doubles the risk of oral, esophageal, and laryngeal cancers compared to non-smokers [6]. However, the same daily cigar smoking habit only raises lung cancer risk by 20-30% [7]. By comparison, smoking 1-2 packs of cigarettes per day increases lung cancer risk by 1300% [8].
So while occasional cigar smoking carries fewer risks than frequent cigarette smoking, it can still be extremely harmful, especially for cancers of the mouth, throat, and esophagus.
Pipes
Like cigars, tobacco pipes are designed for puffing rather than inhaling smoke. However, pipe smoke still contains carcinogens and toxins that can be absorbed by tissues in the mouth and throat. Pipe smoking is associated with an increased risk of cancers in these areas [9].
One study found that smoking a pipe raised lung cancer risk by 2.5 times and esophageal cancer risk by 1.5 times compared to non-smokers [10]. However, due to differences in inhalation, pipe smokers have lower lung cancer rates than cigarette smokers.
Waterpipes
Waterpipes, also known as hookahs, are devices used to smoke specially made tobacco through a bowl and tube partially filled with water. The tobacco smoke passes through the water before being inhaled.
Many incorrectly believe that the water filters out all of the toxins in the smoke. In fact, using a waterpipe still exposes the smoker to high levels of nicotine, tar, carbon monoxide, and other toxins [11].
One meta-analysis found that waterpipe smoking leads to a 2-fold increase in lung cancer risk compared to non-smokers [12]. It also raises the risk of respiratory illness, low birth weight babies, and periodontal disease.
Bidis
Bidis are small, thin hand-rolled cigarettes made of tobacco wrapped in leaves. They originate from India but have gained popularity in some Western countries. Though they contain less tobacco than traditional cigarettes, bidis deliver higher amounts of nicotine and tar [13].
Research shows bidi smoking leads to a 50% higher risk of oral cancer, 30% higher risk of lung cancer, and 100% higher risk of esophageal cancer compared to cigarette smoking [14].
Smokeless tobacco products
Smokeless tobacco products contain tobacco or tobacco blends that are consumed without burning or smoke. Using smokeless tobacco still carries health risks, though they are generally lower than with smoking. Types of smokeless tobacco include:
Chewing tobacco
Chewing tobacco consists of loose tobacco leaves that users place between their cheek and gum to absorb nicotine. It is typically chewed or actively sucked on rather than left sitting in the mouth.
Studies show chewing tobacco users have heightened risks of oral, esophageal, and pancreatic cancers compared to non-users [15]. One analysis found chewing tobacco raised oral cancer risk by 68% [16]. The risk increases the longer chewing is used and the more frequently it is used per day.
Snuff
Snuff is a finely ground version of smokeless tobacco that comes loose or in small pouches. A pinch of snuff can be placed between the lower lip and gum or cheek for absorption through mucus membranes.
While using snuff avoids the risks of smoking, it can still lead to oral and pancreatic cancer with regular long-term use [17]. However, one study found snuff users had just a 16% heightened risk of oral cancer versus 68% for chewing tobacco [16].
Snus
Snus (rhymes with ‘goose’) refers to pasteurized smokeless tobacco products popular in Scandinavia. It is available either loose or in mini teabag-like pouches. Users place snus behind the upper lip for absorption.
Compared to other smokeless tobaccos, snus is linked to fewer health risks. Studies show no connection between snus and pancreatic cancer [18]. A possible association with esophageal cancer has been observed, though the evidence is weak [19]. For oral cancer, snus increases risk but to a lesser degree than chewing tobacco or moist snuff [16].
Secondhand smoke
Secondhand smoke refers to the combination of smoke exhaled by a smoker and smoke drifting from the burning cigarette, cigar, etc. Nonsmokers exposed to secondhand smoke involuntarily inhale toxic chemicals just like active smokers.
There is no risk-free level of exposure to secondhand smoke. It contributes to 41,000 deaths per year among nonsmokers in the U.S. [20].
The risks of secondhand smoke include:
- Lung cancer – nonsmokers exposed to secondhand smoke at home or work increase lung cancer risk by 20-30% [21]
- Heart disease – secondhand smoke exposure raises the likelihood of heart disease by 25-30% even with low levels of exposure [22]
- COPD – secondhand smoke increases risk of COPD and breathing issues like coughing, mucus production, and reduced lung function [23]
There is no major difference in harm between secondhand cigarette, cigar, or pipe smoke. Any secondhand smoke exposure should be minimized.
Thirdhand smoke
Thirdhand smoke refers to the tobacco residue left on indoor surfaces like carpets, walls, furniture, clothes, etc. These deposits can linger long after active smoking takes place. The residues continue emitting chemicals as they interact with other gases and dust in the air [24].
This means thirdhand smoke remains a source of toxin exposure for residents of a contaminated home, hotel room, car, etc. The particles can be transferred to dust, food, and human skin. Though research on thirdhand smoke risks is fairly new, links have been made to cellular and DNA damage [25].
Reducing thirdhand smoke starts with banning smoking indoors and thorough cleaning of homes, cars, and hotels where smoking has occurred. Some states have designated nonsmoking rooms in hotels and passed laws prohibiting smoking in multi-unit residences to help curb thirdhand smoke [26].
Marijuana smoke
Marijuana is often perceived as a less dangerous substance because it is natural. However, smoking marijuana still exposes the lungs and body to toxins. Marijuana smoke contains many of the same carcinogens and irritants found in tobacco smoke [27].
Studies on marijuana’s cancer risk have been mixed. However, evidence suggests regular marijuana smoking could increase lung and oral cancer risk by anywhere from 20-100% compared to nonsmokers [28]. More research is still needed as marijuana use increases.
Secondhand exposure to marijuana smoke may also be harmful, though data is limited. Given the known carcinogens and lung irritants in the smoke, passive marijuana smoke could plausibly lead to respiratory issues or lung damage with repeated exposure [29]. However, secondhand highs are unlikely from limited exposure.
For medical marijuana patients, edibles or oral products would avoid respiratory risks from smoking. However, these can still impact brain development in youth when used recreationally.
Vaping & e-cigarettes
Vaping refers to the use of electronic cigarettes (e-cigarettes) and vaporizer devices to inhale aerosolized liquid mixtures. These liquids typically contain nicotine plus added flavors and chemicals.
Vaping eliminates combustion and smoke, so toxin levels are lower compared to traditional cigarettes. However, vape aerosols still contain small particulates, heavy metals, and cancer-causing agents [30].
One study found vaping just once could impair vascular function as severely as smoking a traditional cigarette [31]. The flavorings added to vaping liquids may also cause inflammation and lung damage when inhaled [32].
So far, direct ties between vaping and cancer have not been made. But given the presence of carcinogens, vaping likely carries some increased cancer risk, especially with long-term use. More research is needed as vaping products continue evolving.
The latest generation of vaping devices, known as mods or ENDS (electronic nicotine delivery systems), allow users to vaporize nearly any liquid. This opens the door to vaping a wide array of unknown and potentially harmful chemical mixtures. According to the CDC, vaping is considered unsafe for teens, young adults, and pregnant women [33].
Is any type of smoking safe?
All forms of smoking carry risks, even marijuana and vaping. No tobacco or nicotine use is completely safe, including smokeless varieties. The only way to avoid health risks associated with smoking is to avoid exposure to tobacco and cannabis smoke completely.
For current smokers, quitting can substantially lower your risk of smoking-related diseases. According to the CDC, within just 5 years of quitting smoking, your risk of cancers of the mouth, throat, esophagus, and bladder are cut in half [34]. Within 10 years of quitting, lung cancer risk drops by half.
Quitting smoking remains one of the best health decisions you can make to reduce your chances of becoming ill or disabled. For help quitting smoking, talk to your doctor or contact local smoking cessation resources.
Conclusion
When it comes to the most harmful types of smoking, the answer largely depends on frequency of use. Frequent cigarette smoking is likely the most dangerous form, exposing your lungs, heart, and other organs to a heavy dose of toxins multiple times per day. Smoking just 1-2 packs per day increases lung cancer risk by over 1000%.
However, smoking any combustible product like cigars, pipes, or marijuana on a regular basis still substantially raises your risks of various cancers, lung disease, and cardiovascular disorders compared to abstaining from smoking. Even smokeless forms carry some risk, especially when used frequently and over many years.
Ultimately, there is no truly safe amount or type of smoking. If you don’t currently smoke, don’t start. If you do smoke, quitting can help regain your health. Talk to your healthcare provider about utilizing quitting resources like counseling, nicotine patches or gum, prescription medications, support groups, or a tobacco treatment clinic. Just 1 year after your last cigarette, your body will already begin to experience the benefits.