PEHRU, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK.
Occup Environ Med. 2010 Oct;67(10):699-707. doi: 10.1136/oem.2009.051714. Epub 2010 Aug 25.
Acute associations between mortality and ozone are largely accepted, though recent evidence is less conclusive. Evidence on ozone-heat interaction is sparse. We assess effects of ozone, heat, and their interaction, on mortality in Britain.
Acute effects of summer ozone on mortality were estimated using data from 15 conurbations in England and Wales (May-September, 1993-2003). 2-day means of daily maximum 8-h ozone were entered into case series analyses, controlling for particulate matter with aerodynamic diameter of <10 μm, natural cubic splines of temperature, and other factors. Heat effects were estimated, comparing adjusted mortality rates at 97.5th and 75th percentiles of 2-day mean temperature. A separate model employed interaction terms to assess whether ozone effects increased on 'hot days' (where 2-day mean temperature exceeded the whole-year 95th percentile). Other heat metrics, and non-linear ozone effects, were also examined.
Adverse ozone and heat effects occurred in nearly all conurbations. The mean mortality rate ratio for heat effect across conurbations was 1.071 (1.050-1.093). The mean ozone rate ratio was 1.003 per 10 μg/m(3) ozone increase (95% CI 1.001 to 1.005). On 'hot days' the mean ozone effect reached 1.006 (1.002-1.009) per 10 μg/m(3), though ozone-heat interaction was significant in London only. On substituting maximum for mean temperature, the overall ozone effect reduced to null, though evidence remained of effects on hot days, particularly in London. An estimated ozone effect threshold was below current guidelines in 'mean temperature' models.
While heat showed robust effects on summer mortality, estimates for ozone depended upon the modelling of temperature. However, there was some evidence that ozone effects were worse on hot days, whichever temperature measure was used.
尽管最近的证据不太确定，但人们普遍接受死亡率与臭氧之间存在急性关联。关于臭氧-热相互作用的证据很少。我们评估了臭氧、高温及其相互作用对英国死亡率的影响。
使用英格兰和威尔士 15 个城市群（1993 年至 2003 年 5 月至 9 月）的数据，估计夏季臭氧对死亡率的急性影响。将每日最大 8 小时臭氧的 2 天平均值纳入病例系列分析，控制了空气动力学直径<10μm 的颗粒物、温度的自然立方样条以及其他因素。通过比较 2 天平均温度的第 97.5 百分位和第 75 百分位的调整死亡率来估计高温的影响。另一个模型采用交互项来评估臭氧效应是否在“热天”（2 天平均温度超过全年第 95 百分位）增加。还检查了其他高温指标和非线性臭氧效应。
几乎所有城市群都出现了不利的臭氧和高温影响。各城市群高温效应的平均死亡率比为 1.071（1.050-1.093）。臭氧的平均比率为每增加 10μg/m3 臭氧增加 1.003（95%CI 1.001 至 1.005）。在“热天”，臭氧的平均效应达到每增加 10μg/m3 增加 1.006（1.002-1.009），尽管伦敦的臭氧-热相互作用仅具有统计学意义。在使用最高温度代替平均温度时，整体臭氧效应降至零，但在“热天”仍有证据表明存在影响，尤其是在伦敦。估计的臭氧效应阈值低于目前“平均温度”模型中的指南。
虽然高温对夏季死亡率有明显影响，但臭氧的估计取决于温度的建模。然而，无论使用哪种温度测量方法，都有一些证据表明臭氧在热天的影响更严重。
