Health burdens of surface ozone in the UK for a range of future scenarios

摘要

Exposure to surface ozone (O_3), which is influenced by emissions of precursor chemical species, meteorology and population distribution, is associated with excess mortality and respiratory morbidity. In this study, the EMEP-WRF atmospheric chemistry transport model was used to simulate surface O_3 concentrations at 5 km horizontal resolution over the British Isles for a baseline year of 2003. for three anthropogenic emissions scenarios for 2030, and for a + 5℃ increase in air temperature on the 2003 baseline. Deaths brought forward and hospitalisation burdens for 12 UK regions were calculated from population-weighted daily maximum 8-hour O_3.The magnitude of changes in annual mean surface O_3 over the UK for +5℃ temperature (+1.0 to +1.5 ppbv, depending on region) was comparable to those due to inter-annual meteorological variability (-1.5 to +1.5 ppbv) but considerably less than changes due to precursor emissions changes by 2030 (- 3.0 to + 3.5 ppbv, depending on scenario and region). Including population changes in 2030, both the 'current legislation' and 'maximum feasible reduction' scenarios yield greater O_3-attributable health burdens than the 'high' emission scenario: +28%, +22%, and +16%. respectively, above 2003 baseline deaths brought forward (11,500) and respiratory hospital admissions (30,700), using O_3 exposure over the full year and no threshold for health effects. The health burdens are greatest under the 'current legislation' scenario because O_3 concentrations increase as a result of both increases in background O_3 concentration and decreases in UK NO_X emissions. For the + 5℃ scenario, and no threshold (and not including population increases), total UK health burden increases by 500 premature deaths (4%) relative to the 2003 baseline. If a 35 ppbv threshold for O_3 effects is assumed, health burdens are more sensitive to the current legislation and + 5 ℃ scenarios, although total health burdens are roughly an order of magnitude lower. In all scenarios, the assumption of a threshold increases the proportion of health burden in the south and east of the UK compared with the no threshold assumption. The study highlights that the total, and geographically-apportioned, O_3-attributable health burdens in the UK are highly sensitive to the future trends of hemispheric, regional and local emissions of O_3 precursors, and to the assumption of a threshold for O_3 effect.