EMERGENCY HOSPITAL ADMISSIONS FOR RESPIRATORY DISORDERS ATTRIBUTABLE TO SUMMER TIME OZONE EPISODES IN GREAT-BRITAIN

Background - There is accumulating evidence from various countries, in cluding the UK, that ground level ozone concentrations are associated with increased daily hospital admissions for respiratory diseases. Thi s paper estimates the impact of ozone episodes on daily hospital admis sions for respiratory disease in Great Britain by combining locally ba sed exposure-response relationships with mapped estimates of ozone exp osure for the population in the summers of 1993 and 1995. Methods - Fo r the given years the available ozone measurements were used to constr uct maps of ozone concentrations for each day. The population exposed to a given concentration of ozone on a particular day was calculated f rom census data using a geographical information system. The additiona l hospital admissions for respiratory disease were then estimated usin g a regression coefficient for London. Results - It is estimated that 0.10% (a total of 184) and 0.35% (a total of 643) of hospital admissio ns for respiratory disorders during the summers of 1993 and 1995, resp ectively, can be attributed to levels of ozone above 50 ppb (the recom mended air quality standard for the UK). A sensitivity analysis for 19 95 found that, if no threshold is assumed, the estimate is increased b y about twenty fold (6% of admissions attributable). Conclusions - The additional hospital admissions for respiratory disease attributable t o ozone are very small in both absolute and relative terms if a thresh old of 50 ppb is assumed, but this estimate is very sensitive to thres hold assumptions.