What is the effect of secondhand smoke on asthma and allergies

A study by the International Agency for Research on Cancer of the World Health Organization concluded that non-smokers are exposed to the same carcinogens as athletic smokers. Sidestream smoke contains more than 4, chemicals, including 69 known carcinogens. Of special concern are polynuclear aromatic hydrocarbons, tobacco-specific N-nitrosamines, and aromatic amines, such as 4-aminobiphenyl, every 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.[2] Several well-established carcinogens own been shown by the tobacco companies’ own research to be present at higher concentrations in sidestream smoke than in mainstream smoke.[]

Secondhand smoke 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 60m³ garage with a limited air exchange. The cigarettes produced PM pollution exceeding outdoor limits, as well as PM concentrations up to fold that of the idling engine.[]

Secondhand 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.[] Secondhand smoke is also associated with impaired vasodilation among adult nonsmokers.[] Secondhand smoke exposure also affects platelet function, vascular endothelium, and myocardial exercise tolerance at levels commonly found in the workplace.[]

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 by-products of third-hand smoke may pose a health risk,[] though the magnitude of risk, if any, remains unknown.

In October , it was reported that Christus St.

What is the effect of secondhand smoke on asthma and allergies

Frances Cabrini Hospital in Alexandria, Louisiana would seek to eliminate third-hand smoke beginning in July , and that employees whose clothing smelled of smoke would not be allowed to work. This prohibition was enacted because third-hand smoke poses a special harm for the developing brains of infants and little children.[]

In , there were more than , deaths attributed to lung cancer in the United States.

What is the effect of secondhand smoke on asthma and allergies

Of these deaths, an estimated 10% to 15% were caused by factors other than first-hand smoking; equivalent to 16, to 24, 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 non-smokers 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 non-smokers as exposure to secondhand tobacco smoke, carcinogens including radon, and other indoor air pollutants.[]

Public opinion

Recent major surveys conducted by the U.S.

National Cancer Institute and Centers for Disease Control own found widespread public awareness that secondhand smoke is harmful. In both and surveys, more than 80% of respondents agreed with the statement that secondhand smoke was harmful. A 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 Gallup poll found that 56% of respondents felt that secondhand smoke was «very harmful», a number that has held relatively steady since Another 29% believe that secondhand smoke is «somewhat harmful»; 10% answered «not too harmful», while 5% said «not at every harmful».[]

Opinion of public health authorities

There is widespread scientific consensus that exposure to secondhand smoke is harmful.[3] The link between passive smoking and health risks is accepted by every major medical and scientific organisation, including:


Secondhand smoke causes numerous of the same diseases as direct smoking, including cardiovascular diseases, lung cancer, and respiratory diseases.[1][2][8] These diseases include:

  • Cancer:
  • Circulatory system: risk of heart disease,[17][18] reduced heart rate variability.[19]
    1. Lung problems:
    2. Passive smoking is strongly associated with an increased risk of stroke, and this increased risk is disproportionately high at low levels of exposure.[21]
    3. Epidemiological studies own shown that both athletic and passive cigarette smoking increase the risk of atherosclerosis.[20]
    4. Cognitive impairment and dementia: Exposure to secondhand smoke may increase the risk of cognitive impairment and dementia in adults 50 and over.[26] Children exposed to secondhand smoke show reduced vocabulary and reasoning skills when compared with non-exposed children as well as more general cognitive and intellectual deficits.[27]
    5. Mental health: Exposure to secondhand smoke is associated with an increased risk of depressive symptoms.[28]
    6. During pregnancy:
  • Lung problems:
  • Cognitive impairment and dementia: Exposure to secondhand smoke may increase the risk of cognitive impairment and dementia in adults 50 and over.[26] Children exposed to secondhand smoke show reduced vocabulary and reasoning skills when compared with non-exposed children as well as more general cognitive and intellectual deficits.[27]
  • Mental health: Exposure to secondhand smoke is associated with an increased risk of depressive symptoms.[28]
  • During pregnancy:
  • General:
    1. Risk of carrying Neisseria meningitidis or Streptococcus pneumoniae.[15]
    2. Type 2 diabetes.[37][38][39] It remains unclear whether the association between passive smoking and diabetes is causal.[40]
    3. Worsening of asthma, allergies, and other conditions.[35] A systematic review and meta-analysis found that passive smoking was associated with a slightly increased risk of allergic diseases among children and adolescents; the evidence for an association was weaker for adults.[36]
    4. A possible increased risk of periodontitis.[41]
    5. Overall increased risk of death in both adults, where it is estimated to kill 53, nonsmokers per year, making it the 3rd leading cause of preventable death in the U.S,[42][43] and in children.[44] The World Health Organization states that passive smoking causes about , deaths a year, and about 1% of the global burden of disease.[45] As of , passive smoking causes about , deaths a year, which is about 1/8 of every deaths caused by smoking.[46]
    6. Skin conditions: A systematic review and meta-analysis found that passive smoking was associated with a higher rate of atopic dermatitis.[47]

    Risk to children

    1. Prenatal and childhood passive smoke exposure does not appear to increase the risk of inflammatory bowel disease.[63]
    2. Learning difficulties, developmental delays, executive function problems,[64] and neurobehavioral effects.[65][66] Animal models propose a role for nicotine and carbon monoxide in neurocognitive problems.[57]
    3. Sudden baby death syndrome (SIDS).[48] In his report, the US Surgeon General concludes: «The evidence is sufficient to infer a causal relationship between exposure to secondhand smoke and sudden baby death syndrome.»[49] Secondhand smoking has been estimated to be associated with SIDS deaths in the United States annually.[50]
    4. Impaired respiratory function and slowed lung growth[59]
    5. Asthma.[51][52][53] Secondhand smoke exposure is also associated with an almost doubled risk of hospitalization for asthma exacerbation among children with asthma.[54]
    6. Miscarriage: a meta-analysis found that maternal secondhand smoke exposure increased the risk of miscarriage by 11%.[72]
    7. An increase in tooth decay (as well as related salivary biomarkers) has been associated with passive smoking in children.[67]
    8. Maternal passive smoking increases the risk of non-syndromic orofacial clefts by 50% among their children.[62]
    9. Invasive meningococcal disease.[15][70]
    10. Allergies[61]
    11. Increased risk of middle ear infections.[57][68][69]
    12. Maternal exposure to secondhand smoke exposure during pregnancy is associated with an increased risk of neural tube defects.[71]
    13. Sleep disordered breathing: Most studies own found a significant association between passive smoking and sleep disordered breathing in children, but further studies are needed to determine whether this association is causal.[74]
    14. Lung infections,[55][56][57] also including more severe illness with bronchiolitis[58] and bronchitis,[59] and worse outcome,[58] as well as increased risk of developing tuberculosis if exposed to a carrier.[60] In the United States, it is estimated that secondhand smoke has been associated with between , and , lower respiratory tract infections in infants and children under 18 months of age, resulting in between 7, and 15, hospitalizations each year.[50]
    15. Anesthesia complications and some negative surgical outcomes.[73]
    16. Adverse effects on the cardiovascular system of children.[75]


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

    Most of the research has come from studies of nonsmokers who are married to a smoker. Those conclusions are also backed up by further studies of workplace exposure to smoke.[76][77]

    In , a review estimated that secondhand smoke exposure was responsible for 35, to 40, deaths per year in the United States in the early s.[78] The absolute risk increase of heart disease due to ETS was %, while the attributable risk percent was 23%. A meta-analysis found that secondhand smoke exposure increased the risk of heart disease by a quarter,[79] and two meta-analyses reached similar conclusions.[80][81]

    Evidence 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 s, though it kept its findings secret.[82][83][84][85] Some scientists believe that the risk of passive smoking, in specific the risk of developing coronary heart diseases, may own been substantially underestimated.[86]

    In , a meta-analysis on the relationship between secondhand smoke exposure and lung cancer concluded that such exposure caused lung cancer.

    The increase in risk was estimated to be 24% among non-smokers who lived with a smoker.[87] In , Copas and Shi reported that there was clear evidence of publication bias in the studies included in this meta-analysis. They further concluded that after correcting for publication bias, and assuming that 40% of every studies are unpublished, this increased risk decreased from 24% to 15%.[88] This conclusion has been challenged on the basis that the assumption that 40% of every studies are unpublished was «extreme».[2] In , Takagi et al.

    reanalyzed the data from this meta-analysis to account for publication bias and estimated that the relative risk of lung cancer among those exposed to secondhand smoke was , slightly lower than the original estimate.[89] A meta-analysis found a relative risk of for lung cancer among men exposed to secondhand smoke, and a relative risk of among those exposed to it at work.[90] Another meta-analysis confirmed the finding of an increased risk of lung cancer among women with spousal exposure to secondhand smoke the following year.

    What is the effect of secondhand smoke on asthma and allergies

    It found a relative risk of lung cancer of for women exposed to secondhand smoke from their spouses.[91] A meta-analysis noted that «the association between exposure to secondhand smoke and lung cancer risk is well established.»[92]

    A minority of epidemiologists own found it hard to understand how secondhand smoke, which is more diluted than actively inhaled smoke, could own an effect that is such a large part of the added risk of coronary heart disease among athletic smokers.[93][94] One proposed explanation is that secondhand smoke is not simply a diluted version of «mainstream» smoke, but has a diverse composition with more toxic substances per gram of entire particulate matter.[93] Passive smoking appears to be capable of precipitating the acute manifestations of cardio-vascular diseases (atherothrombosis) and may also own a negative impact on the outcome of patients who suffer acute coronary syndromes.[95]

    In , the International Agency for Research on Cancer (IARC) of the World Health Organization (WHO) reviewed every 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 second-hand 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.[2]

    Subsequent meta-analyses own confirmed these findings.[96][97]

    The National Asthma Council of Australia cites studies showing that secondhand smoke is probably the most significant indoor pollutant, especially around young children:[98]

    1. The outlook for early childhood asthma is less favourable in smoking households.
    2. Children with asthma who are exposed to smoking in the home generally own more severe disease.
    3. Smoking by either parent, particularly by the mom, increases the risk of asthma in children.
    4. Many adults with asthma identify ETS as a trigger for their symptoms.
    5. 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, exposure to secondhand smoke has been estimated to cause between 3,[99] and 5, premature deaths per year, with the larger figure cited by Prime Minister Dominique de Villepin during his announcement of a nationwide smoke-free law: «That makes more than 13 deaths a day. It is an unacceptable reality in our country in terms of public health.»[]

    There is excellent observational evidence that smoke-free legislation reduces the number of hospital admissions for heart disease.[][]

    Risk level

    The International Agency for Research on Cancer of the World Health Organization concluded in that there was sufficient evidence that secondhand smoke caused cancer in humans.[2] Those who work in environments where smoke is not regulated are at higher risk.

    Workers particularly at risk of exposure include those in installation repair and maintenance, construction and extraction, and transportation.[]

    The US Surgeon General, in his report, estimated that living or working in a put where smoking is permitted increases the non-smokers’ risk of developing heart disease by 25–30% and lung cancer by 20–30%.[] In the U.S., smokers that own not quit successfully own a risk of lung cancer about 20 times higher than that of never smokers.[][]


    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.

    Carbon monoxide monitored through breath, nicotine, cotinine, thiocyanates, and proteins are the most specific biological markers of tobacco smoke exposure.[][] Biochemical tests are a much more dependable biomarker of secondhand smoke exposure than surveys.

    What is the effect of secondhand smoke on asthma and allergies

    Certain groups of people are reluctant to reveal 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.

    What is the effect of secondhand smoke on asthma and allergies

    Also, it may be hard for individuals to recall their exposure to tobacco smoke.[]

    A study in 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. Significant biological levels of nicotine from secondhand smoke exposure were equivalent to nicotine levels from athletic smoking and levels that are associated with behaviour changes due to nicotine consumption.[]


    Cotinine, the metabolite of nicotine, is a biomarker of secondhand smoke exposure.

    What is the effect of secondhand smoke on asthma and allergies

    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 own been a dependable biomarker of tobacco exposure and own been used as a reference in numerous epidemiological studies. However, cotinine levels found in the urine reflect exposure only 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 dependable biomarker.[]

    Carbon monoxide (CO)

    Carbon monoxide monitored via breath is also a dependable biomarker of secondhand smoke exposure as well as tobacco use. With high sensitivity and specificity, it not only provides an precise measure, but the test is also non-invasive, highly reproducible, and low in cost.

    What is the effect of secondhand smoke on asthma and allergies

    Breath CO monitoring measures the concentration of CO in an exhalation in parts per million, and this can be directly correlated to the blood CO concentration (carboxyhemoglobin).[] Breath CO monitors can also be used by emergency services to identify patients who are suspected of having CO poisoning.

    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 secondhand smoke, sought wide publicity for those results.

    The industry also funded libertarian and conservative ponder 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 own 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 numerous characteristics of other forms of denialism, such as HIV-AIDS denialism.[][]

    Industry-funded studies and critiques

    Levois and Layard

    In , Levois and Layard, both tobacco industry consultants, published two analyses in the journal Regulatory Toxicology and Pharmacology regarding the association between spousal exposure to secondhand smoke and heart disease.

    Both of these papers reported no association between secondhand smoke and heart disease.[][] These analyses own been criticized for failing to distinguish between current and previous smokers, despite the fact that previous smokers, unlike current ones, are not at a significantly increased risk of heart disease.[5][]


    Steven Milloy, the «junk science» commentator for Fox News and a previous Philip Morris consultant,[][] claimed that «of the 19 studies» on passive smoking «only 8— slightly more than 42%— reported statistically significant increases in heart disease incidence..»[]

    Another component of criticism cited by Milloy focused on relative risk and epidemiological practices in studies of passive smoking.

    Milloy, who has a master’s 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 own 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 consent to the standards proposed by Philip Morris et al.[]

    Enstrom and Kabat

    A study by James Enstrom and Geoffrey 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, coronary heart disease (CHD), or chronic obstructive pulmonary disease, 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 dependable 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 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 athletic 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 Middle for Indoor Air Research,[] a tobacco industry front group tasked with «offsetting» damaging studies on passive smoking, as well as by Philip Morris who stated that Enstrom’s work was «clearly litigation-oriented.»[] A paper in Tobacco Control argued that the disclosure section in the Enstrom and Kabat BMJ paper, although it met the journal’s requirements, «does not reveal the full extent of the relationship the authors had with the tobacco industry.»[]

    In , Enstrom and Kabat published a meta-analysis of studies regarding passive smoking and coronary heart disease in which they reported a extremely feeble association between passive smoking and heart disease mortality.[] They concluded that exposure to secondhand smoke increased the risk of death from CHD by only 5%, although this analysis has been criticized for including two previous industry-funded studies that suffered from widespread exposure misclassification.[5]


    Gio Batta Gori, a tobacco industry spokesman and consultant[][][] and an expert on risk utility and scientific research, wrote in the libertarianCato Institute’s magazine Regulation that «of the 75 published studies of ETS and lung cancer, some 70% did not report statistically significant differences of risk and are moot.

    Roughly 17% claim an increased risk and 13% imply a reduction of risk.»[]

    World Health Organization controversy

    A study 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 , 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 favorite press and were in fact extremely 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, and concluded the authors found «no association between childhood exposure to ETS and lung cancer risk» but «did discover feeble evidence of a dose–response relationship between risk of lung cancer and exposure to spousal and workplace ETS.»[] An accompanying editorial summarized:

    When every the evidence, including the significant 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 (by Elisa Ong and Stanton Glantz) 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 trade 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.[]

    Tobacco-industry funding of research

    The tobacco industry’s role in funding scientific research on secondhand smoke has been controversial.[] A review of published studies found that tobacco-industry affiliation was strongly correlated with findings exonerating secondhand smoke; researchers affiliated with the tobacco industry were 88 times more likely than independent researchers to conclude that secondhand smoke 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 baby death syndrome.[] The 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 , at which Philip Morris proposed to set up a team of scientists, organized by company lawyers, to «carry out work on ETS to hold the controversy alive.»[] Every 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 numerous scientists on an international basis to hold the ETS controversy alive.»[]

    Tobacco industry response

    Measures to tackle secondhand smoke pose a serious economic threat to the tobacco industry, having broadened the definition of smoking beyond a personal habit to something with a social impact.

    In a confidential report, the tobacco industry described increasing public concerns about secondhand smoke 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 mids 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.»[3]

    Accordingly, the tobacco industry own developed several strategies to minimise the impact on their business:

    1. Funding bias in research;[7] in every reviews of the effects of secondhand smoke on health published between and , the only factor associated with concluding that secondhand smoke is not harmful was whether an author was affiliated with the tobacco industry.[] However, not every studies that failed to discover evidence of harm were by industry-affiliated authors.
    2. Delaying and discrediting legitimate research (see[7] for an example of how the industry attempted to discredit Takeshi Hirayama’s landmark study, and[] for an example of how it attempted to delay and discredit a major Australian report on passive smoking)
    3. The industry has sought to position the secondhand smoke debate as essentially concerned with civil liberties and smokers’ rights rather than with health, by funding groups such as FOREST.[]
    4. 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 () cite an internal Phillip Morris memo giving evidence of this as company policy.[]

    5. Creation of outlets for favourable research. In , 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 quantity 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 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 own 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 own fraudulently denied that ETS causes disease.»[]

    EPA lawsuit

    In , the United States Environmental Protection Agency (EPA) issued a report estimating that 3, 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 , 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 reveal significant findings and reasoning…»

    In , the EPA successfully appealed this decision to the United States Court of Appeals for the Fourth Circuit.

    What is the effect of secondhand smoke on asthma and allergies

    The EPA’s appeal was upheld on the preliminary grounds that their report had no regulatory weight, and the earlier finding was vacated.[]

    In , 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.»[]

    Position of major tobacco companies

    The positions of major tobacco companies on the issue of secondhand smoke is somewhat varied.

    In general, tobacco companies own continued to focus on questioning the methodology of studies showing that secondhand smoke is harmful. Some (such as British American Tobacco and Philip Morris) acknowledge the medical consensus that secondhand smoke carries health risks, while others continue to assert that the evidence is inconclusive. Several tobacco companies advocate the creation of smoke-free areas within public buildings as an alternative to comprehensive smoke-free laws.[]

    US racketeering lawsuit against tobacco companies

    On September 22, , 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, 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).[3] In specific, Judge Kessler found that PM and other tobacco companies had:

    1. conspired to minimize, distort and confuse the public about the health hazards of smoking;
    2. publicly denied, while internally acknowledging, that secondhand tobacco smoke is harmful to nonsmokers, and
    3. destroyed documents relevant to litigation.

    The ruling found that tobacco companies undertook joint efforts to undermine and discredit the scientific consensus that secondhand smoke causes disease, notably by controlling research findings via paid consultants.

    The ruling also concluded that tobacco companies were fraudulently continuing to deny the health effects of ETS exposure.[3]

    On May 22, , a three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit unanimously upheld the lower court’s ruling.[][][]