Short-term exposure to air pollutants has been extensively related to daily mortality, however most of the evidence comes from studies conducted in major cities, and little is known on the extent of the spatial heterogeneity in the effects within areas including both urban and non-urban settings. We aimed to investigate the short-term association of air pollutants with daily cause-specific mortality in the Stockholm county, and to test whether an association exists also outside the metropolitan area. We used a spatiotemporal random forest model to predict daily concentrations of fine and inhalable particulate matter (PM_2.5 and PM₁₀), nitrogen dioxide (NO₂) and ozone (O₃) at 1-km spatial resolution over Sweden for 2005–2016. We collected data on daily mortality for each small area for market statistics (SAMS) of the Stockholm county, to which we matched daily exposures to air pollutants and air temperature. We applied a case-crossover design to investigate the short-term association between the four pollutants and mortality from non-accidental, cardiovascular and respiratory causes. We compared the associations in and out the Stockholm urban area, by SAMS population density and across the 26 municipalities of the county. We found weak effects of most air pollutants on cause-specific mortality in the full year analysis, with estimates much larger and significant only during the warmer months (April to September): non-accidental mortality increased by 4.58% (95% confidence interval – 95% CI: 0.89%, 8.41%) and by 2.21% (95% CI: 0.71%, 3.73%) per 10 μg/m³ increase in lag 0–1 PM_2.5 and O₃, respectively. Associations were in general higher in the Stockholm city and in SAMS with high population density. When comparing the 26 municipalities, we didn't detect a significant heterogeneity in the short-term associations with air pollutants. In conclusion, we found a suggestion of a harmful role of air pollution also in non-urban areas, but the study was underpowered to draw firm conclusions. We consider this study as a pilot to investigate the spatial heterogeneity of the association between daily air pollution and mortality at the national level in Sweden.

短期暴露于空气污染物与每日死亡率有着广泛的关系，但是，大多数证据来自在主要城市进行的研究，而对于城市和非城市地区内影响的空间异质性程度知之甚少城市环境。我们旨在调查斯德哥尔摩县空气污染物与每日特定原因死亡率的短期关联，并检验在大都市区以外是否也存在这种关联。我们使用时空随机森林模型来预测精细和可吸入颗粒物（PM _2.5和PM ₁₀），二氧化氮（NO ₂）和臭氧（O ₃）的日浓度）在2005-2016年间在瑞典的1公里空间分辨率上。我们收集了斯德哥尔摩县每个小区域的每日死亡率数据，以用于斯德哥尔摩县的市场统计（SAMS），并将其与空气污染物和气温的每日暴露进行匹配。我们采用病例交叉设计来研究四种污染物与非意外，心血管和呼吸系统原因造成的死亡率之间的短期关联。我们通过SAMS人口密度以及该县26个市镇比较了斯德哥尔摩市区内外的关联。在全年分析中，我们发现大多数空气污染物对特定原因死亡率的影响微弱，只有在较温暖的月份（4月至9月），估计的影响才大得多且显着：非意外死亡率增加了4.58％（95％置信区间– 95％CI：0.89％，8.41％）和2。³滞后分别增加0–1 PM _2.5和O ₃。斯德哥尔摩市和人口密集的SAMS中的协会一般较高。在比较26个城市时，我们在与空气污染物的短期关联中未发现显着的异质性。总之，我们发现在非城市地区也存在空气污染的有害作用，但这项研究不足以得出明确的结论。我们认为这项研究是在瑞典国家一级研究每日空气污染与死亡率之间关系的空间异质性的先驱。