Passive smoking: summary of new findings from California EPA report

Friday 17 October 1997

ASH/ Press releases/


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Press release17 October 1997 ASH
Action on Smoking
and Health



Environmental tobacco smoke (ETS) is a major indoor air pollutant. ETSis a complex mixture of chemicals generated during the burning and smoking of tobaccoproducts. Chemicals present in tobacco smoke include toxins and carcinogens such asformaldehyde, benzene and hydrogen cyanide. The US Environmental Protection Agency hasclassified ETS as a class A (known human) carcinogen.

The scientific evidence of a causal relationship between environmentaltobacco smoke (passive smoking) and diseases such as lung cancer, childhood asthma, andlower respiratory tract infections is now firmly established. A review of the scientificliterature by the State of California has confirmed previous findings and has alsorevealed that ETS is causally associated with a number of conditions for which there hadnot previously been sufficient evidence to make such an association.

The report by the Californian Office of Environmental Health HazardAssessment also gives data on the incidence of specific diseases caused by passivesmoking. Using this data, it is possible to give an approximate calculation of the numberof cases attributable to passive smoking that can be expected in the UK. Despite anincreasing number of restrictions on smoking in public places and an increased awarenessof the health consequences, exposure to passive smoking continues to be a major publichealth concern. This is especially true for children, who are more sensitive to therespiratory effects of passive smoking. For children, the home remains the single mostimportant location for exposure to passive smoking. A study by the Health EducationAuthority has shown that over half (55 per cent) of 11-15 year olds live in householdswhere at least one person smokes.

Scientific evidence of the health consequences of passive smoking

Since the early 1980s, when the evidence of the health impact ofpassive smoking began to emerge, a number of comprehensive reviews of the effects ofpassive smoking have been published. These include:

The UK Independent Scientific Committee on Smoking and Health reportedin 1988 that the risk of lung cancer in nonsmokers exposed to passive smoking was in theorder of 10% to 30%, that is, from about 10 to 11-13 per 100,000 per year. This means thatseveral hundred of the 40,000 lung cancer deaths every year may be attributable to passivesmoking.

In addition, the US Environmental Protection Agency, the NationalResearch Council and the 1986 Report of the US Surgeon General found ETS exposure to becausally linked with respiratory illnesses, including lung cancer, childhood asthma andlower respiratory tract infections.

New findings from the California review

Scientific knowledge about the effects of ETS has grown considerablysince the publication of the above reviews. The State of California therefore undertook abroad review of the health impact of ETS. The report also presents an overview of themeasurements of ETS exposure and of the prevalence of ETS exposure in California andacross the USA. On the basis of the data provided in this report, it is possible toextrapolate approximate data for corresponding health outcomes in the UK population. (seeannex 1)

The OEHHA report shows for example that ETS is an independent riskfactor for:

  • Sudden Infant Death Syndrome
  • Asthma induction and exacerbation in children
  • Nasal sinus cancer
  • Acute and chronic heart disease morbidity
  • Heart disease mortality

In addition, the report has found suggestive evidence of a causalassociation between ETS exposure and:

  • Spontaneous abortion
  • Cervical cancer
  • Exacerbation of cystic fibrosis


Specific findings

  • Sudden Infant Death Syndrome (Cot death)

Numerous studies have demonstrated an increased risk of sudden infantdeath syndrome (SIDS) in infants of mothers who smoke. Until recently, it has not beenpossible to separate the effects of postnatal ETS exposure from those of prenatal exposureto maternal active smoking. Recent epidemiological studies have now demonstrated that postnatalETS exposure is an independent cause of SIDS.

  • Asthma

There is now compelling evidence that ETS is a risk factor for inductionof new cases of asthma as well as for increasing the severity of disease amongchildren with established asthma.

  • Nasal sinus cancer

Consistent associations between ETS and nasal sinus cancer have beendemonstrated, presenting strong evidence that ETS exposure increases the risk of nasalsinus cancers in nonsmoking adults. Further study is needed to determine the magnitudeof the risk.

  • Acute and chronic heart disease morbidity and mortality

ETS exposure from spousal smoking has been identified as a risk factorfor coronary heart disease mortality in nonsmokers. For nonsmokers exposed to spousal ETScompared to nonsmokers not exposed, the risk of CHD mortality is increased by a factor of1.3. For the UK, this means that up to 12,000 nonsmokers are at risk of CHD as a resultof breathing in their spouse’s tobacco smoke.



ETS or passive smoking causes a number of fatal and non-fatal healtheffects. Heart disease, mortality, sudden infant death syndrome, and lung and nasal sinuscancer have been causally linked to ETS exposure. Serious effects on the young includechildhood induction and exacerbation, bronchitis and pneumonia, middle ear infection,chronic respiratory symptoms, and low birth weight. In adults, acute and chronic heartdisease is causally associated with ETS exposure. While the relative health risks aresmall compared to those from active smoking because the diseases are common the overallhealth impact is large. Based on the California findings, it is estimated that there atleast 2 million incidences of illnesses caused by passive smoking every year in the UK.In view of the considerable health impact of passive smoking, particularly on the young,measures to restrict smoking in indoor environments should be a major public healthobjective.



October 1997


Contact Clive Bates, Director (020) 7739 5902
Amanda Sandford, Communications Director (020) 7739 5902

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