Shin Hwashin Hyun, Owen James G, Mitchell Kimberly Megan, Smith-Doiron Marc, Dehghani Parvin
Environmental Health Science and Research Bureau, Health Canada, 269 Laurier Ave. W., Ottawa, ON, K1A 0K9, Canada.
Department of Mathematics and Statistics, Queen's University, Kingston, ON, Canada.
BMC Public Health. 2025 Mar 31;25(1):1217. doi: 10.1186/s12889-025-22339-6.
Nitrogen dioxide (NO) is a highly reactive gas produced mainly from burning fossil fuels. Exposure to NO has been shown to impact public health worldwide. However, spatial and temporal variations in its effects by season, age, and sex have been underexamined.
We conducted an ecological time-series study based on about 20 million people (52% of Canadians in 2012) in three regions (Western, Central and Eastern Canada) over 17 years (1996-2012). We collected hourly NO concentrations and temperatures, and daily counts of non-accidental all-cause, circulatory-, and respiratory-related hospitalizations, including more specific causes: ischemic heart disease, other heart disease, cerebrovascular disease, influenza/pneumonia, and chronic lower respiratory disease. We first estimated city-specific risks, applying over-dispersed generalized Poisson models, and then regional and national risks for each season, age-group, and sex using Bayesian hierarchical models. We also applied Sen's test to detect linear trends in annual regional and national risks.
We found significant NO effects by cause, season, age, sex, and linear trend. For circulatory hospitalization, only Western Canada showed significant adverse effects for non-seniors (≤ 65) (1.7% with 95% credible interval of 0.3-3.2% per 10 ppb increase in NO), and for males for more specific cause, ischemic heart disease (2.3%, 0.1-4.5%). Regional differences were observed for circulatory but not respiratory hospitalizations. For example, the Western and Eastern regions were at significantly higher risk of circulatory hospitalization but not the Central region: 1.6% (0.2-3.0%) for the Western region; 2.0% (0.6-3.4%) for the Eastern region; and 0.8% (-0.3-2.0%) for the Central region. In particular, the Western region had a much higher risk of cerebrovascular disease hospitalization: 2.8% (1.1-4.6%) for the Western region; 0.1% (-3.0-3.1%) for the Central region; and 0.0% (-3.4-3.5%) for the Eastern region. However, no other regional differences were observed for other causes. Overall, there were noticeable increases in regional differences over time, particularly in the later years.
This study indicates harmful NO effects on acute hospitalizations year-round: circulatory causes (cold season) and respiratory causes (warm season). Future work is warranted to investigate potential causes of observed regional differences using more community-related information such as socioeconomic status, health-care accessibility, and others.
二氧化氮（NO）是一种主要由燃烧化石燃料产生的高活性气体。已表明接触二氧化氮会对全球公众健康产生影响。然而，其影响在季节、年龄和性别方面的时空变化尚未得到充分研究。
我们基于17年（1996 - 2012年）间加拿大三个地区（西部、中部和东部）约2000万人（占2012年加拿大人的52%）开展了一项生态时间序列研究。我们收集了每小时的二氧化氮浓度和温度，以及非意外全因、循环系统相关和呼吸系统相关住院的每日计数，包括更具体的病因：缺血性心脏病、其他心脏病、脑血管疾病、流感/肺炎和慢性下呼吸道疾病。我们首先应用过度分散的广义泊松模型估计特定城市的风险，然后使用贝叶斯分层模型估计每个季节、年龄组和性别的区域和国家风险。我们还应用森氏检验来检测年度区域和国家风险的线性趋势。
我们发现二氧化氮的影响在病因、季节、年龄、性别和线性趋势方面具有显著性。对于循环系统住院，仅加拿大西部地区显示非老年人（≤65岁）有显著不良影响（二氧化氮每增加10 ppb，风险为1.7%，95%可信区间为0.3 - 3.2%），对于男性，更具体的病因缺血性心脏病有显著影响（2.3%，0.1 - 4.5%）。在循环系统住院方面观察到区域差异，但呼吸系统住院方面未观察到。例如，西部地区和东部地区循环系统住院风险显著更高，而中部地区则不然：西部地区为1.6%（0.2 - 3.0%）；东部地区为2.0%（0.6 - 3.4%）；中部地区为0.8%（ - 0.3 - 2.0%）。特别是，西部地区脑血管疾病住院风险要高得多：西部地区为2.8%（1.1 - 4.6%）；中部地区为0.1%（ - 3.0 - 3.1%）；东部地区为0.0%（ - 3.4 - 3.5%）。然而，其他病因未观察到其他区域差异。总体而言，随着时间推移，区域差异有明显增加，尤其是在后期。
本研究表明二氧化氮全年对急性住院有有害影响：循环系统病因（寒冷季节）和呼吸系统病因（温暖季节）。有必要开展进一步研究，利用更多与社区相关的信息，如社会经济地位、医疗可及性等，来调查观察到的区域差异的潜在原因。
