Yorifuji Takashi, Suzuki Etsuji, Kashima Saori
Department of Human Ecology, Graduate School of Environmental and Life Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
Environ Health. 2014 Aug 13;13:67. doi: 10.1186/1476-069X-13-67.
Epidemiological studies have shown adverse effects of short-term exposure to air pollution on respiratory disease outcomes; however, few studies examined this association on an hourly time scale. We evaluated the associations between hourly changes in air pollution and the risk of respiratory disease in the elderly, using the time of the emergency call as the disease onset for each case.
We used a time-stratified case-crossover design. Study participants were 6,925 residents of the city of Okayama, Japan, aged 65 or above who were taken to hospital emergency rooms between January 2006 and December 2010 for onset of respiratory disease. We calculated city-representative hourly average concentrations of air pollutants from several monitoring stations. By using conditional logistic regression models, we estimated odds ratios per interquartile-range increase in each pollutant by exposure period prior to emergency call, adjusting for hourly ambient temperature, hourly relative humidity, and weekly numbers of reported influenza cases aged ≥60.
Suspended particulate matter (SPM) exposure 24 to <72 hours prior to the onset and ozone exposure 48 to <96 hours prior to the onset were associated with the increased risk of respiratory disease. For example, following one interquartile-range increase, odds ratios were 1.05 (95% confidence interval: 1.01, 1.09) for SPM exposure 24 to <48 hours prior to the onset and 1.13 (95% confidence interval: 1.04, 1.23) for ozone exposure 72 to <96 hours prior to the onset. Sulfur dioxide (SO2) exposure 0 to <24 hours prior to onset was associated with the increased risk of pneumonia and influenza: odds ratio was 1.07 per one interquartile-range increase (95% confidence interval: 1.00, 1.14). Elevated risk for pneumonia and influenza of SO2 was observed at shorter lags (i.e., 8-18 hours) than the elevated risks for respiratory disease of SPM or ozone. Overall, the effect estimates for chronic obstructive pulmonary disease and allied conditions were equivocal.
This study provides further evidence that hourly changes in air pollution exposure increase the risks of respiratory disease, and that SO2 may be related with more immediate onset of the disease than other pollutants.
流行病学研究表明，短期接触空气污染会对呼吸道疾病产生不良影响；然而，很少有研究在小时时间尺度上考察这种关联。我们以每个病例的急救电话时间作为疾病发病时间，评估了空气污染的每小时变化与老年人呼吸道疾病风险之间的关联。
我们采用了时间分层病例交叉设计。研究参与者为日本冈山市65岁及以上的6925名居民，他们在2006年1月至2010年12月期间因呼吸道疾病发作被送往医院急诊室。我们根据多个监测站的数据计算了具有城市代表性的空气污染物每小时平均浓度。通过使用条件逻辑回归模型，我们估计了在急救电话前每个暴露时间段内，每种污染物每增加一个四分位数间距的比值比，并对每小时的环境温度、每小时的相对湿度以及每周报告的≥60岁流感病例数进行了调整。
发病前24至<72小时的悬浮颗粒物（SPM）暴露以及发病前48至<96小时的臭氧暴露与呼吸道疾病风险增加有关。例如，在增加一个四分位数间距后，发病前24至<48小时的SPM暴露的比值比为1.05（95%置信区间：1.01，1.09），发病前72至<96小时的臭氧暴露的比值比为1.13（95%置信区间：1.04，1.23）。发病前0至<24小时的二氧化硫（SO₂）暴露与肺炎和流感风险增加有关：每增加一个四分位数间距的比值比为1.07（95%置信区间：1.00，1.14）。观察到SO₂导致肺炎和流感的风险升高的滞后时间（即8 - 18小时）比SPM或臭氧导致呼吸道疾病风险升高的滞后时间更短。总体而言，慢性阻塞性肺疾病及相关病症的效应估计不明确。
本研究进一步证明，空气污染暴露的每小时变化会增加呼吸道疾病风险，并且SO₂可能比其他污染物与疾病的发病更为直接相关。
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