Passive smoking is the involuntary inhalation of smoke from tobacco products. It occurs when tobacco smoke permeates any environment, causing its inhalation by all people within that environment. Such smoke is called secondhand smoke (SHS) or environmental tobacco smoke (ETS). Scientific evidence shows that exposure to secondhand tobacco smoke causes disease, disability, and death.
There is some evidence that reducing exposure to tobacco smoke cuts the risk of heart attack. When Helena, Montana implemented a 100% smokefree law, heart attack admissions in the local hospital dropped by 40%, and rebounded when a court suspended the law. Heart attack admissions have been shown by meta-analysis to drop by an average 27% after the implementation of smoke-free laws.
Adults or children with asthma can experience attacks brought on by passive smoking, and there has been one case study report of a death due to an asthma attack associated with passive smoking. Since the 1980s there has been substantial evidence that there is a relationship between parents smoking in the house and children developing asthma and other related illnesses. 2002). There have also been studies that investigated the exposure to tobacco smoke with the age of the child. Research has shown that the younger the child-as young as a fetus even-- the more susceptible and harmful the effects of second hand smoking can be. These children of smokers tend to have a lung capacity that is less than children of the same height,weight, age, and sex of those children who are not exposed to constant second hand smoke.Children who are exposed to cigarette smoke in their home day after day are more likely to cough, wheeze, get sore throats, and respiratory problems than children who live in homes with non-smokers.Although it is not indefinite that the increased amount of asthma amongst children is primarily due to environmental tobacco smoke, there is substantial evidence that leads to the conclusion that it has a tremendous impact on it.
Tobacco smoke is an irritant, and allergy sufferers can experience stuffy or runny noses, watery or burning eyes, sneezing, coughing, wheezing, a feeling of suffocation, and other typical allergy symptoms within minutes of exposure.
Many former smokers, and those who are trying to quit prefer to not be around smoke as it can cause them to have cravings.
A wide array of negative effects are attributed, in whole or in part, to frequent, long term exposure to second hand smoke. Some of these effects include:
A study issued in 2002 by the International Agency for Research on Cancer of the World Health Organization concluded that nonsmokers are exposed to the same carcinogens as active smokers. Sidestream smoke contains more than 4000 chemicals, including 69 known carcinogens such as formaldehyde, lead, arsenic, benzene, and radioactive polonium 210, and several well-established carcinogens have been shown by the tobacco companies' own research to be present at higher concentrations in sidestream smoke than in mainstream smoke.
Environmental tobacco smoke (ETS) has been shown to be a much higher source of pollution than an idling ecodiesel engine in regard to particulate matter (PM) emission. In an experiment conducted by the Tobacco Control Unit of the National Cancer Institute, three cigarettes were left smouldering, one after the other, in a 60 m³ garage with a limited air exchange. The cigarettes produced PM indoor pollution exceeding outdoor limits, as well as PM concentrations up to 10-fold that of the idling engine.
Tobacco smoke exposure has immediate and substantial effects on blood and blood vessels in a way that increases the risk of a heart attack, particularly in people already at risk. Exposure to tobacco smoke for 30 minutes significantly reduces coronary flow velocity reserve in healthy nonsmokers.
In 1992, the Journal of the American Medical Association published a review of the available evidence regarding the relationship between secondhand smoke and heart disease, and estimated that passive smoking was responsible for 35,000 to 40,000 deaths per year in the United States in the early 1980s. Some studies find that non-smokers living with smokers have about a 25% increase in risk of death from heart attack, are more likely to suffer a stroke, and can sometimes contract genital cancer. Some research, with better measures of secondhand smoke exposure suggests that risks to nonsmokers may be even greater than this estimate. A British study reported that exposure to secondhand smoke increases the risk of heart disease among non-smokers by as much as 60%, similar to light smoking.
Parental smoking can affect children and babies, and is associated with low birth weight, sudden infant death syndrome (SIDS), bronchitis and pneumonia, and middle ear infections.
In 2002, a group of 29 experts from 12 countries convened by the Monographs Programme of the International Agency for Research on Cancer (IARC) of the World Health Organization (WHO) reviewed all significant published evidence related to tobacco smoking and cancer. It concluded:
These meta-analyses show that there is a statistically significant and consistent association between lung cancer risk in spouses of smokers and exposure to secondhand tobacco smoke from the spouse who smokes. The excess risk is of the order of 20% for women and 30% for men and remains after controlling for some potential sources of bias and confounding.
Subsequent meta-analyses have confirmed these findings, and additional studies have found that high overall exposure to passive smoke even among people with non-smoking partners is associated with greater risks than partner smoking and is widespread in non-smokers.
The National Asthma Council of Australia cites studies showing that environmental tobacco smoke (ETS) is probably the most important indoor pollutant, especially around young children:
In France passive smoking has been estimated to cause between 3,000 and 5,000 premature deaths per year, with the larger figure cited by Prime minister Dominique de Villepin during his announcement of a nationwide smoking ban: "That makes more than 13 deaths a day. It is an unacceptable reality in our country in terms of public health."
There is limited evidence in experimental animals for the carcinogenicity of mixtures of mainstream and sidestream tobacco smoke.
There is sufficient evidence in experimental animals for the carcinogenicity of sidestream smoke condensates.
Secondhand smoke is generally recognized as a risk factor for cancer in pets. A study conducted by the Tufts University School of Veterinary Medicine and the University of Massachusetts concluded that cats living with a smoker were more likely to get feline lymphoma; the risk increased with the duration of exposure to secondhand smoke and the number of smokers in the household. A study by Colorado State University researchers, looking at cases of canine lung cancer, was generally inconclusive, though the authors reported a weak relation for lung cancer in dogs exposed to environmental tobacco smoke.
In 1990, a tobacco-industry researcher in Germany proposed a study of the effects on animals of lifetime exposure to secondhand smoke. The proposed study was blocked by Philip Morris, as described in an internal company report:
PM [Philip Morris] recently succeeded in blocking Adlkofer's plan to conduct lifetime animal inhalation study of sidestream smoke. (. . .an INBIFO study has shown that in 90-day inhalation test, no non-reversible changes has [sic] been detected. In a lifetime study, the results were almost certain to be less favorable. Based on the analysis, the other members of the German industry agreed that the proposed study should not proceed.)
There is sufficient evidence that involuntary smoking (exposure to secondhand or 'environmental' tobacco smoke) causes lung cancer in humans.
Involuntary smoking (exposure to secondhand or 'environmental' tobacco smoke) is carcinogenic to humans (Group 1).
Most experts believe that moderate, occasional exposure to secondhand smoke presents a small but measurable cancer risk to nonsmokers. The overall risk depends on the effective dose received over time. The risk is more significant if non-smokers spend many hours in an environment where cigarette smoke is prevalent, such as a business where many employees or patrons are smoking throughout the day, or a residential care facility where residents smoke freely.
The health effects of secondhand smoke exposure are more pervasive than we previously thought. The scientific evidence is now indisputable: secondhand smoke is not a mere annoyance. It is a serious health hazard that can lead to disease and premature death in children and nonsmoking adults.
The study estimated that living or working in a place where smoking is permitted increases the non-smokers' risk of developing heart disease by 25–30% and lung cancer by 20–30%. The report also found that passive smoke causes sudden infant death syndrome (SIDS), respiratory problems, ear infections, and asthma attacks in children.
While there is scientific agreement regarding the existence of a link between passive smoking and heart disease, the magnitude of the increased risk remains debated by a minority of epidemiologists. For example, John Bailar of the National Academy of Sciences questioned the proportionality of the passive smoking risk, stating:
Regular smoking only increases the risk of cardiovascular disease by 75%, so how could second-hand smoke, which is much more dilute, have an effect one-third that size?
One proposed explanation is that secondhand smoke is not simply a diluted version of "mainstream" smoke, but has a different composition with more toxic substances per gram of total particulate matter. The more toxic makeup of secondhand smoke was first recognized in the tobacco industry's own research, though it never published its findings. Some scientists believe that the risk of passive smoking, in particular the risk of developing coronary heart diseases, may have been substantially underestimated.
The health benefit to non-smokers of smoking bans has also been disputed by a small number of epidemiologists, who call for a prospective trial to more accurately determine the benefit. These epidemiologists advocate indoor smoking bans, but express a concern that widespread outdoor smoking bans, as implemented by some towns in the U.S., may be unsupported by the evidence available thus far.
A 2007 Gallup poll found that 56% of respondents felt that secondhand smoke was "very harmful", a number that has held relatively steady since 1997. Another 29% believe that secondhand smoke is "somewhat harmful"; 10% answered "not too harmful", while 5% said "not at all harmful". Regarding smoking bans, the poll found a majority (54%) in favor of complete smoking bans in restaurants; however, most respondents favored designated smoking areas in hotels, motels and workplaces. In bars, the survey found that 45% prefer smoking areas, 29% support a smoking ban, and 23% want no restrictions on smoking.
In 1986, the United States Surgeon General issued a report concluding that secondhand smoke was a cause of disease. In the same year, the International Agency for Research on Cancer and the National Research Council also released reports concluding that secondhand smoke was a cause of lung cancer. Over the subsequent 20 years, the accumulation of scientific evidence has led to a scientific consensus that passive smoking is indeed harmful to non-smokers. A U.S. District Court found, in a racketeering case against the tobacco industry, that the industry had internally acknowledged the harmfulness of passive smoking even earlier., pp. 1523–1525 Nonetheless, the tobacco industry has played a central role in generating and sustaining controversy over the effects of passive smoking.
A number of studies funded by the tobacco industry have yielded results inconsistent with the scientific consensus, or have criticised the epidemiological approach associated with that consensus.
A 2003 study by Enstrom and Kabat, published in the British Medical Journal, argued that the harms of passive smoking had been overstated. Their analysis reported no statistically significant relationship between passive smoking and lung cancer, though the accompanying editorial noted that "they may overemphasise the negative nature of their findings. This paper was widely promoted by the tobacco industry as evidence that the harms of passive smoking were unproven., p. 1383 The American Cancer Society (ACS), whose database Enstrom and Kabat used to compile their data, criticized the paper as "neither reliable nor independent", stating that scientists at the ACS had repeatedly pointed out serious flaws in Enstrom and Kabat' s methodology prior to publication. Enstrom's ties to the tobacco industry also drew scrutiny; in a 1997 letter to Philip Morris, Enstrom requested a "substantial research commitment... in order for me to effectively compete against the large mountain of epidemiologic data and opinions that already exist regarding the health effects of ETS and active smoking. The study was funded and managed by the Center for Indoor Air Research, a tobacco industry front group described in confidential Philip Morris documents as "responsible for producing studies to offset the IARC study" on passive smoking, and Enstrom's work was viewed by Philip Morris as "clearly litigation-oriented.", pp. 1380–1383 Enstrom himself has defended the accuracy of his study against what he terms "illegitimate criticism by those who have attempted to suppress and discredit it.
Gio Batta Gori, a tobacco industry consultant and spokeperson, wrote in the libertarian Cato Institute's journal Regulation that "...of the 75 published studies of ETS and lung cancer, some 70 percent did not report statistically significant differences of risk and are moot. Roughly 17 percent claim an increased risk and 13 percent imply a reduction of risk. Steven Milloy, the "junk science" commentator for Fox News and a former Philip Morris consultant, claimed that "...of the 37 studies [on passive smoking], only 7 – less than 19 percent – reported statistically significant increases in lung cancer incidence.
Another component of criticism promoted by Milloy focused on relative risk and epidemiological practices in studies of passive smoking. Milloy argued that studies yielding relative risks of less than 2 were meaningless junk science. This approach to epidemiological analysis was criticized in the American Journal of Public Health:
A major component of the industry attack was the mounting of a campaign to establish a "bar" for "sound science" that could not be fully met by most individual investigations, leaving studies that did not meet the criteria to be dismissed as "junk science.
The tobacco industry and affiliated scientists also put forward a set of "Good Epidemiology Practices" which would have the practical effect of obscuring the link between secondhand smoke and lung cancer; the privately-stated goal of these standards was to "impede adverse legislation". However, this effort was largely abandoned when it became clear that no independent epidemiological organization would agree to the standards proposed by Philip Morris et al.
A 1998 report by the International Agency for Research on Cancer (IARC) on environmental tobacco smoke (ETS) found "weak evidence of a dose-response relationship between risk of lung cancer and exposure to spousal and workplace ETS. In March 1998, before the study was published, reports appeared in the media alleging that the IARC and the World Health Organization (WHO) were suppressing information. The reports, appearing in the British Sunday Telegraph and The Economist, among other sources, alleged that the WHO withheld from publication its own report that supposedly failed to prove an association between passive smoking and a number of other diseases (lung cancer in particular).
In response, the WHO issued a press release stating that the results of the study had been "completely misrepresented" in the popular press and were in fact very much in line with similar studies demonstrating the harms of passive smoking. The study was published in the Journal of the National Cancer Institute in October of the same year. An accompanying editorial summarized:
When all the evidence, including the important new data reported in this issue of the Journal, is assessed, the inescapable scientific conclusion is that ETS is a low-level lung carcinogen.
With the release of formerly classified tobacco industry documents through the Tobacco Master Settlement Agreement, it was found that the controversy over the WHO's alleged suppression of data had been engineered by Philip Morris, British American Tobacco, and other tobacco companies in an effort to discredit scientific findings which would harm their business interests. A WHO inquiry, conducted after the release of the tobacco-industry documents, found that this controversy was generated by the tobacco industry as part of its larger campaign to cut the WHO's budget, distort the results of scientific studies on passive smoking, and discredit the WHO as an institution. This campaign was carried out using a network of ostensibly independent front organizations and international and scientific experts with hidden financial ties to the industry.
The United States District Court for the Middle District of North Carolina ruled in favor of the tobacco industry in 1998, finding that the EPA had failed to follow proper scientific and epidemiologic practices and had "cherry picked" evidence to support conclusions which they had committed to in advance. The court stated in part, "“EPA publicly committed to a conclusion before research had begun…adjusted established procedure and scientific norms to validate the Agency's public conclusion... In conducting the ETS Risk Assessment, disregarded information and made findings on selective information; did not disseminate significant epidemiologic information; deviated from its Risk Assessment Guidelines; failed to disclose important findings and reasoning…"
In 2002, the EPA successfully appealed this decision to the United States Court of Appeals for the Fourth Circuit. The EPA's appeal was upheld on the preliminary grounds that their report had no regulatory weight, and the earlier finding was vacated. In 1998 the U.S. Department of Health and Human Services, through the publication by its National Toxicology Program of the 9th Report on Carcinogens, listed environmental tobacco smoke among the known carcinogens, observing of the EPA assessment that "The individual studies were carefully summarized and evaluated.p. 24
The industry has funded or carried out research that has been judged to be biased, supported scientists to generate letters to editors that criticized research publications, attempted to undermine the findings of key studies, assisted in establishing a scientific society with a journal, and attempted to sustain controversy even as the scientific community reached consensus.
This strategy was outlined at an international meeting of tobacco companies in 1988, at which Philip Morris proposed to set up a team of scientists, organized by company lawyers, to "carry out work on ETS to keep the controversy alive." All scientific research was subject to oversight and "filtering" by tobacco-industry lawyers:
Philip Morris then expect the group of scientists to operate within the confines of decisions taken by PM scientists to determine the general direction of research, which apparently would then be 'filtered' by lawyers to eliminate areas of sensitivity.
Philip Morris reported that it was putting "...vast amounts of funding into these projects... in attempting to coordinate and pay so many scientists on an international basis to keep the ETS controversy alive."
Accordingly, the tobacco industry have developed several strategies to minimize its impact on their business:
Citing the tobacco industry's production of biased research and efforts to undermine scientific findings, the 2006 U.S. Surgeon General's report concluded that the industry had "attempted to sustain controversy even as the scientific community reached consensus... industry documents indicate that the tobacco industry has engaged in widespread activities... that have gone beyond the bounds of accepted scientific practice. The U.S. District Court, in U.S.A. v. Philip Morris et al., found that "...despite their internal acknowledgment of the hazards of secondhand smoke, Defendants have fraudulently denied that ETS causes disease.", p. 1523
Non-smokers who breathe air containing ambient smoke are often referred to as passive smokers and many studies have been conducted to assess their risks. Some studies on exposure to ambient smoke conclude that it represents a risk for health.British American Tobacco (site accessed on July 27, 2007)
The World Health Organisation, the United States Surgeon General and other public health bodies have concluded that exposure to environmental tobacco smoke (ETS), sometimes called ‘second-hand smoke’, is a cause of various serious diseases, including lung cancer, heart disease and respiratory illnesses in children.Imperial Tobacco Group plc (site accessed on November 19, 2006)
They conclude that there is no known safe level of ETS exposure and hence advise that public health policy would be best served by bans on public smoking.
Our view of the science
The risks associated with ETS have been measured in epidemiological studies. These mainly use questionnaires to compare the incidence of diseases such as lung cancer in non-smoking women whose husbands were smokers, with non-smoking women whose husbands were non-smokers.
For lung cancer, the major studies report that relative risk associated with prolonged non-smoker exposure to ETS is 1.3. A relative risk of 1 means no risk, and prolonged active smoking is typically associated with a relative risk of lung cancer of the order of 20 or higher.
For heart disease, the major studies also report a relative risk for ETS exposure of around 1.3. The relative risk for active smoking and heart disease is typically of the order of 3 to 5.
Many epidemiologists say that relative risks below 2 are weak associations and are more difficult to quantify than stronger associations. Perhaps because the relative risks reported in individual studies tend to be below 2, many studies do not reach statistical significance.
Studies of respiratory illnesses in children whose parents smoke, and research into whether ETS exposure exacerbates symptoms for people with conditions such as asthma, suggest that ETS can increase risks of respiratory illnesses in children and can affect people with pre-existing conditions such as asthma.
Our approach to regulation
We support regulation that accommodates the interests of both non-smokers and smokers and limits non-smokers’ involuntary exposure to ETS.
We favour restrictions on smoking in enclosed public places and we accept that there needs to be regulation.
We support practical initiatives such as the creation of smoke-free areas, combined with adequate provision for smokers.
Imperial Tobacco recognises that other people’s tobacco smoke can be unpleasant or annoying, and can raise concerns leading to calls to ban smoking . However, it is our view that the scientific evidence, taken as a whole, is insufficient to establish that other people’s tobacco smoke is a cause of any disease.JT International (Japan Tobacco) (site accessed on November 19, 2006)
The statistical population studies (epidemiology) which have led to claims that other people’s tobacco smoke is a risk to health are subject to some methodological flaws. Most individual studies show no statistical effects. When study results are combined (a process called ‘meta analysis’), at most they indicate a very small increase in relative risk.
We agree that ETS can be annoying to non-smokers and that in poorly ventilated areas ETS can cause substantial irritation of the eyes, nose and throat. We therefore ask all smokers to be aware of and show consideration for people with whom they come into contact. However, we do not believe that the claim that ETS is a cause of lung cancer, heart disease and chronic pulmonary diseases in non-smokers has been convincingly demonstrated or that a reliable causal link between ETS exposure and chronic diseases has been established.Philip Morris USA (site accessed on November 19, 2006)
Public health officials have concluded that secondhand smoke from cigarettes causes disease, including lung cancer and heart disease, in non-smoking adults, as well as causes conditions in children such as asthma, respiratory infections, cough, wheeze, otitis media (middle ear infection) and Sudden Infant Death Syndrome. In addition, public health officials have concluded that secondhand smoke can exacerbate adult asthma and cause eye, throat and nasal irritation.R.J. Reynolds Tobacco Company (site accessed on November 19, 2006)
Philip Morris USA believes that the public should be guided by the conclusions of public health officials regarding the health effects of secondhand smoke in deciding whether to be in places where secondhand smoke is present, or if they are smokers, when and where to smoke around others. Particular care should be exercised where children are concerned, and adults should avoid smoking around them.
We also believe that the conclusions of public health officials concerning environmental tobacco smoke are sufficient to warrant measures that regulate smoking in public places. We also believe that where smoking is permitted, the government should require the posting of warning notices that communicate public health officials' conclusions that secondhand smoke causes disease in non-smokers.
RJRT believes that individuals should rely on the conclusions of the U.S. Surgeon General, the Centers for Disease Control and other public health and medical officials when making decisions regarding smoking.
These initial bans have grown in scope, with countries (such as Ireland, the UK, Australia), jurisdictions (like New York State, Washington State, Ohio, Pennsylvania, and Arkansas in the U.S.) now prohibiting smoking in public buildings as well as establishments such as restaurants and clubs. Many office buildings contain specially ventilated smoking areas; some are required by law to provide them.
The state of Hawaii recently passed a bill making it illegal to smoke in any public place or within 20 feet of an entrance or ventilation shaft intake of a building.
Some regions and local governments have banned smoking in all workplaces, in taxicabs, and in ventilated smoking rooms or enclosed smoking shelters such as those found in front of hospitals.
Even in countries traditionally seen as nations of smokers , opinion polls have shown support for bans, with 70% of those in France supporting a ban.
In the first 18 months after the town of Pueblo, Colorado enacted a smoking ban in 2003, hospital admissions for heart attacks dropped 27%. Admissions in neighboring towns without smoking bans showed no change. Raymond Gibbons, M.D., American Heart Association president said, "The decline in the number of heart attack hospitalizations within the first year and a half after the non-smoking ban that was observed in this study is most likely due to a decrease in the effect of secondhand smoke as a triggering factor for heart attacks.