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, exposure to secondhand smoke 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 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 good observational evidence that smoke-free legislation reduces the number of hospital admissions for heart disease. exposure and risk levels 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. 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. much research has come from studies of nonsmokers who are married to a smoker. 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%. similarly, children who are exposed to environmental tobacco smoke are shown to experience a range of adverse effects and a higher risk of becoming smokers later in life. the who has identified reduction of exposure to environmental tobacco smoke as key element for actions to encourage healthy child development. the us centers for disease control and prevention monitors the extent of and trends in exposure to environmental tobacco smoke by measuring serum cotinine in national health surveys. the prevalence of secondhand smoke exposure among u.s. nonsmokers declined from 87.5% in 1988 to 25.2% in 2014. however, nearly half of blacks and the poor were exposed in 2014. interventions to reduce environmental tobacco smoke a systematic review compared smoking control programmes and their effects on smoke exposure in children. the review distinguishes between community-based, ill-child and healthy-child settings and the most common types of interventions were counselling or brief advice during clinical visits. the review did not find superior outcomes for any intervention, and the authors caution that evidence from adult settings may not generalise well to children. biomarkers breath co monitor displaying carbon monoxide concentration of an exhaled breath sample (in ppm) with corresponding percent concentration of carboxyhemoglobin displayed below 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 reliable biomarker of secondhand smoke exposure 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, it may be difficult for individuals to recall their exposure to tobacco smoke. a 2007 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 active smoking and levels that are associated with behaviour changes due to nicotine consumption. cotinine cotinine, the metabolite of nicotine, is a biomarker of secondhand 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 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 reliable biomarker. carbon monoxide (co) carbon monoxide monitored via breath is also a reliable biomarker of secondhand smoke exposure as well as tobacco use. with high sensitivity and specificity, it not only provides an accurate measure, but the test is also non-invasive, highly reproducible, and low in cost. 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. pathophysiology a 2004 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 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. 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 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. 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 2011, it was reported that christus st. frances cabrini hospital in alexandria, louisiana, would seek to eliminate third-hand smoke beginning in july 2012, 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 danger for the developing brains of infants and small children. 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 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. 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 organisation, including: world health organization u.s. national institutes of health centers for disease control united states surgeon general u.s. national cancer institute united states environmental protection agency california environmental protection agency american heart association, american lung association, and american cancer society american medical association american academy of pediatrics australian national health and medical research council united kingdom scientific committee on tobacco and health public opinion recent major surveys conducted by the u.s. national cancer institute and centers for disease control have found widespread public awareness 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 secondhand smoke, 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 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 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 philip morris who stated that enstrom's work was "clearly litigation-oriented". a 2005 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 2006, enstrom and kabat published a meta-analysis of studies regarding passive smoking and coronary heart disease in which they reported a very weak 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. gori gio batta gori, a tobacco industry spokesman