Table 3

Change in the prevalence of work related sensitisation, upper respiratory symptoms, lower respiratory symptoms and work disability for the different intervention scenarios

ScenarioDisease statePrevalence
Change*2.5% CI
Covenant interventionWork related sensitisation−13%−17% to −10%
Upper respiratory symptoms−6%−8% to −3%
Lower respiratory symptoms−13%−16% to −10%
Work disabling asthmatic symptoms−13%−29% to +3%
Continuation of covenantWork related sensitisation−21%−26% to −17%
Upper respiratory symptoms−14%−17% to −10%
Lower respiratory symptoms−25%−30% to −20%
Work disabling asthmatic symptoms−24%−38% to −12%
Hygienic interventionWork related sensitisation−21%−25% to −17%
Upper respiratory symptoms−21%−26% to −16%
Lower respiratory symptoms−46%−52% to −40%
Work disabling asthmatic symptoms−46%−57% to −33%
Health surveillance intervention (I)Work related sensitisation3%−1% to 8%
Upper respiratory symptoms−4%−8% to 0%
Lower respiratory symptoms−31%−40% to −22%
Work disabling asthmatic symptoms−30%−45% to −15%
Health surveillance intervention (II)Work related sensitisation−2%−6% to 2%
Upper respiratory symptoms18%7% to 28%
Lower respiratory symptoms−58%−66% to −50%
Work disabling asthmatic symptoms−59%−71% to −45%
Pre-employment screeningWork related sensitisation−21%−31% to −13%
Upper respiratory symptoms−14%−23% to −4%
Lower respiratory symptoms−18%−26% to −6%
Work disabling asthmatic symptoms−16%−35% to 4%
  • * Difference between pre- and post-intervention period over a 20-year period.

  • For work disabling asthma the figures reflect the change in onset of new cases; since disabled workers leave the workforce in the year they become disabled no prevalence figures can be estimated for this stage.