Passive smoking

Passive smoking is the inhalation of smoke, called secondhand smoke (SHS) or environmental tobacco smoke (ETS), from tobacco products used by others. It occurs when tobacco smoke permeates any environment, causing its inhalation by people within that environment. Exposure to secondhand tobacco smoke causes disease, disability, and death. Currently, the health risks of secondhand smoke are a matter of scientific consensus, and these risks have been a major motivation for smoking bans in workplaces and indoor public places, including restaurants, bars and night clubs, as well as some open public spaces.

Passive smoking has played a central role in the debate over the harms and regulation of tobacco products. Since the early 1970s, the tobacco industry has viewed public concern over secondhand smoking as a serious threat to its business interests. Harm to bystanders was perceived as a motivator for stricter regulation of tobacco products. Despite the industry's awareness of the harms of secondhand smoke as early as the 1980s, the tobacco industry coordinated a scientific controversy with the aim of forestalling regulation of their products.

Effects
Secondhand smoke causes many of the same diseases as direct smoking, including cardiovascular diseases, lung cancer, and respiratory diseases. These diseases include:


 * Cancer:
 * General: overall increased risk; reviewing the evidence accumulated on a worldwide basis, the International Agency for Research on Cancer concluded in 2004 that "Involuntary smoking (exposure to secondhand or 'environmental' tobacco smoke) is carcinogenic to humans."
 * Lung cancer: the effect of passive smoking on lung cancer has been extensively studied. A series of studies from the USA from 1986–2003, the UK in 1998,  Australia in 1997 and internationally in 2004 have consistently shown a significant increase in relative risk among those exposed to passive smoke.
 * Breast cancer: The California Environmental Protection Agency concluded in 2005 that passive smoking increases the risk of breast cancer in younger, primarily premenopausal women by 70% and the US Surgeon General has concluded that the evidence is "suggestive," but still insufficient to assert such a causal relationship. In contrast, the International Agency for Research on Cancer concluded in 2004 that there was "no support for a causal relation between involuntary exposure to tobacco smoke and breast cancer in never-smokers."
 * Renal cell carcinoma (RCC): A recent study shows an increased RCC risk among never smokers with combined home/work exposure to passive smoking.
 * Passive smoking does not appear to be associated with pancreatic cancer.
 * Brain tumor: The risk in children increases significantly with higher amount of passive smoking, even if the mother doesn't smoke, thus not restricting risk to prenatal exposure during pregnancy.
 * Ear, nose, and throat: risk of ear infections.
 * Secondhand smoke exposure is associated with hearing loss in non-smoking adults.
 * Circulatory system: risk of heart disease, reduced heart rate variability, higher heart rate.
 * Epidemiological studies have shown that both active and passive cigarette smoking increase the risk of atherosclerosis.
 * Lung problems:
 * Risk of asthma.
 * Cognitive impairment and dementia: Exposure to secondhand smoke may increase the risk of cognitive impairment and dementia in adults 50 and over.
 * During pregnancy:
 * Low birth weight, part B, ch. 3.
 * Premature birth, part B, ch. 3 (Note that evidence of the causal link is only described as "suggestive" by the US Surgeon General in his 2006 report. )
 * Recent studies comparing women exposed to Environmental Tobacco Smoke and non-exposed women, demonstrate that women exposed while pregnant have higher risks of delivering a child with congenital abnormalities, longer lengths, smaller head circumferences, and low birth weight.
 * General:
 * Worsening of asthma, allergies, and other conditions.
 * Risk to children
 * Sudden infant death syndrome (SIDS). In his 2006 report, the US Surgeon General concludes: "The evidence is sufficient to infer a causal relationship between exposure to secondhand smoke and sudden infant death syndrome."
 * Asthma
 * Lung infections
 * More severe illness with bronchiolitis, and worse outcome
 * Increased risk of developing tuberculosis if exposed to a carrier
 * Allergies
 * Crohn's disease.
 * Learning difficulties, developmental delays, and neurobehavioral effects. Animal models suggest a role for nicotine and carbon monoxide in neurocognitive problems.
 * An increase in tooth decay (as well as related salivary biomarkers) has been associated with passive smoking in children.
 * Increased risk of middle ear infections.
 * Skin Disorder
 * Childhood exposure to Environmental Tobacco Smoke is associated with an increased risk of the development of adult-onset Atopic dermatitis.
 * Overall increased risk of death in both adults, where it is estimated to kill 53,000 nonsmokers per year, making it the 3rd leading cause of preventable death in the U.S. and in children. Another research financed by the Swedish National Board of Health and Welfare and Bloomberg Philanthropies found that passive smoking causes about 603,000 death a year, which represents 1% of the world's death.

Evidence
Epidemiological studies show that non-smokers exposed to secondhand smoke are at risk for many of the health problems associated with direct smoking.

In 1992, the Journal of the American Medical Association published a review of available evidence on 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. The absolute risk increase of heart disease due to ETS was 2.2%, while the attributable risk percent was 23%.

Research using more exact 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. Evidence also shows that inhaled sidestream smoke, the main component of secondhand smoke, is about four times more toxic than mainstream smoke. This fact has been known to the tobacco industry since the 1980s, though it kept its findings secret. Some scientists believe that the risk of passive smoking, in particular the risk of developing coronary heart diseases, may have been substantially underestimated.

A minority of epidemiologists find it hard to understand how environmental tobacco smoke, which is far more dilute than actively inhaled smoke, could have an effect that is such a large fraction of the added risk of coronary heart disease among active smokers. 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. Passive smoking appears to be capable of precipitating the acute manifestations of cardio-vascular diseases (atherothrombosis) and may also have a negative impact on the outcome of patients who suffer acute coronary syndromes.

In 2004, 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:


 * Smoking by either parent, particularly by the mother, increases the risk of asthma in children.
 * The outlook for early childhood asthma is less favourable in smoking households.
 * Children with asthma who are exposed to smoking in the home generally have more severe disease.
 * Many adults with asthma identify ETS as a trigger for their symptoms.
 * Doctor-diagnosed asthma is more common among non-smoking adults exposed to ETS than those not exposed. Among people with asthma, higher ETS exposure is associated with a greater risk of severe attacks.

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 good observational evidence that smoke-free legislation reduces the number of hospital admissions for heart disease. In 2009 two studies in the United States confirmed the effectiveness of public smoking bans in preventing heart attacks. The first study, done at the University of California, San Francisco and funded by the National Cancer Institute, found a 15 percent decline in heart-attack hospitalizations in the first year after smoke-free legislation was passed, and 36 percent after three years. The second study, done at the University of Kansas School of Medicine, showed similar results. Overall, women, nonsmokers, and people under age 60 had the most heart attack risk reduction. Many of those benefiting were hospitality and entertainment industry workers.

Risk level
The International Agency for Research on Cancer of the World Health Organization concluded in 2004 that there was sufficient evidence that secondhand smoke caused cancer in humans. 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 level is higher if non-smokers spend many hours in an environment where cigarette smoke is widespread, such as a business where many employees or patrons are smoking throughout the day, or a residential care facility where residents smoke freely. The US Surgeon General, in his 2006 report, 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%.

Biomarkers
Environmental Tobacco Smoke can be evaluated either by directly measuring tobacco smoke pollutants found in the air or by using biomarkers, an indirect measure of exposure. As of 2005, Nicotine, cotinine, thiocyanates, and proteins are the most specific biological markers of tobacco smoke exposure.


 * Cotinine
 * Cotinine, the metabolite of Nicotine, is the preferred biomarker of Environmental Tobacco Smoke exposure. Typically, Cotinine is measured in the blood, saliva, and urine. Hair analysis has recently become a new, noninvasive measurement technique. Cotinine accumulates in hair during hair growth, which results in a measure of long-term, cumulative exposure to tobacco smoke.
 * Urinary cotinine levels have been a reliable biomarker of tobacco exposure and have been used as a reference in many epidemiological studies. However, cotinine levels found in the urine only reflect exposure over the preceding 48 hours. Cotinine levels of the skin, such as the hair and nails, reflect tobacco exposure over the previous three months and are a more reliable biomarker.
 * Cotinine is a much more reliable biomarker of Environmental Tobacco Smoke than surveys. Certain groups of people are reluctant to disclose their smoking status and exposure to tobacco smoke, especially pregnant women and parents of young children. This is due to their smoking being socially unacceptable. Also, recall of tobacco smoke exposure may be difficult. Cotinine measurements are therefore more reliable biomarkers.

In 2007, the Addictive Behaviors Journal found a positive correlation between secondhand tobacco smoke exposure and concentrations of nicotine and/or biomarkers of nicotine in the body. A significant amount of biological levels of nicotine from secondhand smoke exposure were equivalent to nicotine levels from active smoking and levels that are associated with behavior changes due to nicotine consumption.

Pathophysiology
A 2004 study 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 4,000 chemicals, including 69 known carcinogens. Of special concern are polynuclear aromatic hydrocarbons, tobacco-specific N-nitrosamines, and aromatic amines, such as 4-Aminobiphenyl, all known to be highly carcinogenic. Mainstream smoke, sidestream smoke, and secondhand smoke contain largely the same components, however the concentration varies depending on type of smoke. 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 produce more particulate-matter (PM) pollution than an idling low-emission diesel engine. In an experiment conducted by the Italian National Cancer Institute, three cigarettes were left smoldering, one after the other, in a 60 m³ garage with a limited air exchange. The cigarettes produced PM 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.

Pulmonary emphysema can be induced in rats through acute exposure to sidestream tobacco smoke (30 cigarettes per day) over a period of 45 days. Degranulation of mast cells contributing to lung damage has also been observed.

The term "third-hand smoke" was recently coined to identify the residual tobacco smoke contamination that remains after the cigarette is extinguished and secondhand smoke has cleared from the air. Preliminary research suggests that byproducts of thirdhand smoke may pose a health risk, though the magnitude of risk, if any, remains unknown.

In 2008, there were more than 161,000 deaths attributed to lung cancer in the United States. Of these deaths, an estimated 10% to 15% were caused by factors other than first-hand smoking; equivalent to 16,000 to 24,000 deaths annually. Slightly more than half of the lung cancer deaths caused by factors other than first-hand smoking were found in nonsmokers. Lung cancer in nonsmokers may well be considered one of the most common cancer mortalities in the United States. Clinical epidemiology of lung cancer has linked the primary factors closely tied to lung cancer in nonsmokers as exposure to second-hand tobacco smoke, carcinogens including radon, and other indoor air pollutants.

Opinion of public health authorities
There is widespread scientific consensus that exposure to secondhand smoke is harmful. The link between passive smoking and health risks is accepted by every major medical and scientific organization, including:


 * The World Health Organization : The governments of 168 nations have signed and currently 170 have ratified the World Health Organization Framework Convention on Tobacco Control, which states that "Parties recognize that scientific evidence has unequivocally established that exposure to tobacco smoke causes death, disease and disability."
 * The U.S. National Institutes of Health
 * The Centers for Disease Control
 * The United States Surgeon General
 * The U.S. National Cancer Institute
 * The United States Environmental Protection Agency
 * The California Environmental Protection Agency
 * The American Heart Association, American Lung Association, and American Cancer Society
 * The American Medical Association
 * The American Academy of Pediatrics
 * The Australian National Health and Medical Research Council
 * The United Kingdom Scientific Committee on Tobacco and Health



Public opinion
In the Tuileries Garden of Paris, Charles Vernier satirically illustrated a woman "taking a breath of fresh air" in 1860, entirely surrounded by male smokers. Second-hand smoke was viewed as an inconvenience.

Recent major surveys conducted by the U.S. National Cancer Institute and Centers for Disease Control have found widespread public belief that secondhand smoke is harmful. In both 1992 and 2000 surveys, more than 80% of respondents agreed with the statement that secondhand smoke was harmful. A 2001 study found that 95% of adults agreed that secondhand smoke was harmful to children, and 96% considered tobacco-industry claims that secondhand smoke was not harmful to be untruthful.

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".

Controversy over harm
As part of its attempt to prevent or delay tighter regulation of smoking, the tobacco industry funded a number of scientific studies and, where the results cast doubt on the risks associated with passive smoking, sought wide publicity for those results. The industry also funded libertarian and conservative think tanks, such as the Cato Institute in the United States and the Institute of Public Affairs in Australia which criticised both scientific research on passive smoking and policy proposals to restrict smoking. New Scientist and the European Journal of Public Health have identified these industry-wide coordinated activities as one of the earliest expressions of corporate denialism. Further, they state that the disinformation spread by the tobacco industry has created a tobacco denialism movement, sharing many characteristics of other forms of denialism, such as HIV-AIDS denialism.

Enstrom and Kabat
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. 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. Notably, the study had failed to identify a comparison group of "unexposed" persons.

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." In a US racketeering lawsuit against tobacco companies, the Enstrom and Kabat paper was cited by the US District Court as "a prime example of how nine tobacco companies engaged in criminal racketeering and fraud to hide the dangers of tobacco smoke." The Court found that the study had been funded and managed by the Center for Indoor Air Research, a tobacco industry front group tasked with "offsetting" damaging studies on passive smoking, as well as by Phillip Morris who stated that Enstrom's work was "clearly litigation-oriented." Enstrom has defended the accuracy of his study against what he terms "illegitimate criticism by those who have attempted to suppress and discredit it."

Gori
Gio Batta Gori, a tobacco industry spokesman and consultant  and an expert on risk utility and scientific research, 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."

Milloy
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 cited by Milloy focused on relative risk and epidemiological practices in studies of passive smoking. Milloy, who has a masters degree from the Johns Hopkins School of Hygiene and Public Health, 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.

World Health Organization controversy
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 of 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.

EPA lawsuit
In 1993, the United States Environmental Protection Agency (EPA) issued a report estimating that 3,000 lung cancer related deaths in the United States were caused by passive smoking annually.

Philip Morris, R.J. Reynolds Tobacco Company, and groups representing growers, distributors and marketers of tobacco took legal action, claiming that the EPA had manipulated this study and ignored accepted scientific and statistical practices.

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."

Tobacco-industry funding of research
The tobacco industry's role in funding scientific research on passive smoking has been controversial. A review of published studies found that tobacco-industry affiliation was strongly correlated with findings exonerating passive smoking; researchers affiliated with the tobacco industry were 88 times more likely than independent researchers to conclude that passive smoking was not harmful. In a specific example which came to light with the release of tobacco-industry documents, Philip Morris executives successfully encouraged an author to revise his industry-funded review article to downplay the role of secondhand smoke in sudden infant death syndrome. The 2006 U.S. Surgeon General's report criticized the tobacco industry's role in the scientific debate:

"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."

Tobacco industry response
The passive smoking issue poses a serious economic threat to the tobacco industry. It has broadened the definition of smoking beyond a personal habit to something with a social impact. In a confidential 1978 report, the tobacco industry described increasing public concerns about passive smoking as "the most dangerous development to the viability of the tobacco industry that has yet occurred." In United States of America v. Philip Morris et al., the District Court for the District of Columbia found that the tobacco industry "... recognized from the mid-1970s forward that the health effects of passive smoking posed a profound threat to industry viability and cigarette profits," and that the industry responded with "efforts to undermine and discredit the scientific consensus that ETS causes disease."

Accordingly, the tobacco industry have developed several strategies to minimize its impact on their business:


 * The industry has sought to position the passive smoking debate as essentially concerned with civil liberties and smokers' rights rather than with health, by funding groups such as FOREST.
 * Funding bias in research; in all reviews of the effects of passive smoking on health published between 1980 and 1995, the only factor associated with concluding that passive smoking is not harmful was whether an author was affiliated with the tobacco industry. However, not all studies that failed to find evidence of harm were by industry-affiliated authors.
 * Delaying and discrediting legitimate research (see for an example of how the industry attempted to discredit Hirayama's landmark study, and for an example of how it attempted to delay and discredit a major Australian report on passive smoking)
 * Promoting "good epidemiology" and attacking so-called junk science (a term popularised by industry lobbyist Steven Milloy): attacking the methodology behind research showing health risks as flawed and attempting to promote sound science . Ong & Glantz (2001) cite an internal Phillip Morris memo giving evidence of this as company policy
 * Creation of outlets for favorable research. In 1989, the tobacco industry established the International Society of the Built Environment, which published the peer-reviewed journal Indoor and Built Environment. This journal did not require conflict-of-interest disclosures from its authors. With documents made available through the Master Settlement, it was found that the executive board of the society and the editorial board of the journal were dominated by paid tobacco-industry consultants. The journal published a large amount of material on passive smoking, much of which was "industry-positive".

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."

Position of major tobacco companies
The positions of major tobacco companies on the issue of passive smoking is somewhat varied. In general, tobacco companies have continued to focus on questioning the methodology of studies showing that passive smoking is harmful. Some (such as British American Tobacco and Philip Morris) acknowledge the medical consensus that passive smoking carries health risks, while others continue to assert that the evidence is inconclusive. Imperial Tobacco describes secondhand smoke as "annoying" and "unpleasant", but denies any associated health risks. Several tobacco companies advocate the creation of smoke-free areas within public buildings as an alternative to outright smoking bans.

US racketeering lawsuit against tobacco companies
On September 22, 1999, the U.S. Department of Justice filed a racketeering lawsuit against Philip Morris and other major cigarette manufacturers. Almost 7 years later, on August 17, 2006 U.S. District Court Judge Gladys Kessler found that the Government had proven its case and that the tobacco company defendants had violated the Racketeer Influenced Corrupt Organizations Act (RICO). In particular, Judge Kessler found that PM and other tobacco companies had: The ruling found that tobacco companies undertook joint efforts to undermine and discredit the scientific consensus that passive smoking causes disease, notably by controlling research findings via paid consultants. The ruling also concluded that tobacco companies continue today to fraudulently deny the health effects of ETS exposure.
 * conspired to minimize, distort and confuse the public about the health hazards of smoking;
 * publicly denied, while internally acknowledging, that secondhand tobacco smoke is harmful to nonsmokers, and
 * destroyed documents relevant to litigation.

On May 22, 2009, a three-judge panel of the Washington, D.C. U.S. Court of Appeals unanimously upheld the lower court's 2006 ruling.

Smoking bans
As a consequence of the health risks associated with passive smoking, smoking bans in indoor public places, including restaurants, cafés, and nightclubs have been introduced in a number of jurisdictions, at national or local level, as well as some outdoor open areas. 1 Ireland was the first country in the world to institute an outright national ban on smoking in all indoor workplaces on 29 March 2004. Since then, many others have followed suit. The countries which have ratified the WHO Framework Convention on Tobacco Control (FCTC) have a legal obligation to implement effective legislation "for protection from exposure to tobacco smoke in indoor workplaces, public transport, indoor public places and, as appropriate, other public places." (Article 8 of the FCTC ) The parties to the FCTC have further adopted Guidelines on the Protection from Exposure to Secondhand Smoke which state that "effective measures to provide protection from exposure to tobacco smoke ... require the total elimination of smoking and tobacco smoke in a particular space or environment in order to create a 100% smoke free environment."

Opinion polls have shown considerable support for bans. In June 2007, a survey of 15 countries found 80% approval of smoking bans. A survey in France, reputedly a nation of smokers, showed 70% supporting a ban.

Effects
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, and the decline in heart attacks in Pueblo was attributed to the smoking ban.

In April, 2010 the Canadian Medical Association Journal published a study evaluating the effects of a 10-year, three-stage smoking ban in Toronto. The study found that during the implementation of a restaurant smoking ban, hospital admissions for cardiovascular conditions declined by 39%, and admissions for respiratory conditions declined by 33%. No significant reductions in hospital admissions occurred in other cities which did not have smoking bans. The authors concluded that the study justified further efforts to reduce public exposure to tobacco smoke. In May 2006, Ontario instituted a comprehensive province-wide ban on smoking which extended the restrictions to all cities and municipalities in Ontario. However, not all researchers agree that this was a causal relationship, and a 2009 study of many smoking bans in the United States disagreed with these conclusions.

In 2001, a systematic review for the Guide to Community Preventative Services acknowledged strong evidence of the effectiveness of smoke-free policies and restrictions in reducing expose to environmental tobacco smoke. A follow up to this review, identified the evidence on which the effectiveness of smoking bans reduced the prevalence of tobacco use. Articles published until 2005, were examined to further support this evidence. The examined studies provided sufficient evidence that smoke-free policies reduce tobacco use among workers when implemented in worksites or by communities.

While a number of studies funded by the tobacco industry have claimed a negative economic impact of smoking bans, no independently funded research has shown any such impact. A 2003 review reported that independently funded, methodologically sound research consistently found either no economic impact or a positive impact from smoking bans.

Air nicotine levels were measured in Guatemalan bars and restaurants before and after an implemented smoking ban in 2009. Nicotine concentrations significantly decreased in both the bars and restaurants measured. Also, the employees support for a smoke-free workplace substantially increased in the post-ban survey compared to pre-ban survey. The result of this smoking ban provides a considerable more healthy work environment for the staff.

Public opinion
Recent surveys taken by the Society for Research on Nicotine and Tobacco demonstrates supportive attitudes of the public, towards smoke-free policies in outdoor areas. A vast majority of the public supports restricting smoking in various outdoor settings. The respondents reasons for supporting the polices were for varying reasons such as, litter control, establishing positive smoke-free role models for youth, reducing youth opportunities to smoke, and avoiding exposure to secondhand smoke.

Alternative forms
Alternatives to smoking bans have also been proposed as a means of harm reduction, particularly in bars and restaurants. For example, critics of bans cite studies suggesting ventilation as a means of reducing tobacco smoke pollutants and improving air quality. Ventilation has also been heavily promoted by the tobacco industry as an alternative to outright bans, via a network of ostensibly independent experts with often undisclosed ties to the industry. However, not all critics have connections to the industry.

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) officially concluded in 2005 that while completely isolated smoking rooms do eliminate the risk to nearby non-smoking areas, smoking bans are the only means of completely eliminating health risks associated with indoor exposure. They further concluded that no system of dilution or cleaning was effective at eliminating risk. The U.S. Surgeon General and the European Commission Joint Research Centre have reached similar conclusions. The implementation guidelines for the WHO Framework Convention on Tobacco Control states that engineering approaches, such as ventilation, are ineffective and do not protect against secondhand smoke exposure. However, this does not necessarily mean that such measures are useless in reducing harm, only that they fall short of the goal of reducing exposure completely to zero.

Others have suggested a system of tradable smoking pollution permits, similar to the cap-and-trade pollution permits systems used by the Environmental Protection Agency in recent decades to curb other types of pollution. This would guarantee that a portion of bars/restaurants in a jurisdiction will be smoke free, while leaving the decision to the market.

In other animals
Multiple studies have been conducted to determine the carcinogenicity of environmental tobacco smoke to animals. These studies typically fall under the categories of simulated environmental tobacco smoke, administering condensates of sidestream smoke, or observational studies of cancer among pets.

To simulate environmental tobacco smoke, scientists expose animals to sidestream smoke, that which emanates from the cigarette's burning cone and through its paper, or a combination of mainstream and sidestream smoke. The IARC monographs conclude that mice with prolonged exposure to simulated environmental tobacco smoke, that is 6hrs a day, 5 days a week, for five months with a subsequent 4 month interval before dissection, will have significantly higher incidence and multiplicity of lung tumors than with control groups.

The IARC monographs concluded that sidestream smoke condensates had a significantly higher carcinogenic effect on mice than did mainstream smoke condensates.

Observational studies
Secondhand smoke is popularly 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 linked the occurrence of feline oral cancer to exposure to environmental tobacco smoke through an overexpression of the p53 gene. Another study conducted at the same universities 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. The number of smokers within the home, the number of packs smoked in the home per day, and the amount of time that the dog spent within the home had no effect on the dog's risk for lung cancer.

Animal nicotine poisoning
Animals like dogs, cats, squirrels, and other small animals are affected by not only second-hand smoke inhalation, but also nicotine poisoning. Domestic pets, especially dogs, usually fall ill when owners leave nicotine products like cigarette butts, chewing tobacco, or nicotine gum within reach of the animal. Littered cigarette butts from smokers are a problem for small animals that mistake them for food if they find them on sidewalks or trashcans. Cigarette butts are the remains of a cigarette after smoking which contain the filter which is meant to contain tar, particles, and toxins from the cigarette such as ammonia, arsenic, benzene, turpentine and other toxins.