Table 4

Effects of varying key assumptions on estimates of future mortality caused by second hand smoke (SHS)

Assumption Alternative conditions Effect on number of future deaths per year
1. SHS raises risk of stroke death (RR for men 2.1, for women 1.7)SHS does not affect the risk of dying from strokeDecreased by 26% (new n=243.2)
2. Best estimate RR from meta-analyses or original papersUpper 95% confidence limit of all RRsIncreased by 52% (n=490.4)
Lower 95% confidence limit of all RRsDecreased by 46% (n=174.6)
3. Ex-smokers susceptible to effects of SHS Ex-smokers not susceptible to effects of SHS: proportion of deaths among never smokers: heart disease 0.22 (males), 0.28 (females)12; stroke 0.3113 Decreased by 45% (n=180.0)
4. Current smokers not susceptible to SHSRegard all deaths from lung cancer, heart disease, and stroke as influenced by SHSIncreased by 87% (n=606.8)
5. Workplace exposure to SHS affects risk of heart disease beyond age 65Workplace exposure to SHS does not affect risk beyond age 65 Decreased by 6% (n=306.4)
6. Exposure to SHS at work excludes exposures at tea and lunch breaks,
pe = 0.135
Exposure at work defined as “more than 1 cigarette per day smoked around you at work, including lunch and tea breaks”, pe=0.356 (males), 0.246 (females)9 Increased by 16% (n=390.5)
7. No change in future exposures to SHSPrevalence of SHS exposure reduced by: 50% in the home; 90% at workDecreased by 55% (n=146.0)
8. Effect of exposure to SHS at home is independent of exposure at workExposure to SHS at work does not add to risk of disease in those exposed also at home (effectively, prevalence of exposure at work reduced by 20%)Decreased by 4% (n=312.3)
  • RR, relative risk.