Centre for Environmental and Occupational Health Research, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa.
Centre for Environmental and Occupational Health Research, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa; Division of Occupational Medicine, University of Cape Town, Cape Town, South Africa.
Environ Res. 2020 Jul;186:109606. doi: 10.1016/j.envres.2020.109606. Epub 2020 Apr 27.
No previous epidemiological study has investigated the combined association of long-term ambient nitrogen dioxide (NO) and particulate matter of diameter size-2.5 (PM) exposure with asthma outcomes among schoolchildren in Africa.
This study investigated the independent and co-pollutant association of long-term exposures to ambient air pollutants on asthma-associated outcomes in a cohort of schoolchildren in the Western Cape Province of South Africa.
A total of 590 grade-4 schoolchildren residing in four informal settlements were studied. Spirometry and fractional exhaled nitric-oxide (FeNO) measurements were conducted, including a standardized questionnaire administered to caregivers at baseline and 12-months follow-up. Annual NO and PM levels were estimated for each child's home using land-use regression modelling. Single- and two-pollutant models were constructed to assess the independent and co-pollutant association of both air pollutants (NO and PM) on new cases of asthma-associated outcomes adjusting-for host characteristics, indoor exposures and study area.
The annual average concentration of PM and NO were 10.01μg/m and 16.62μg/m respectively, across the four study areas, and were below the local Standards of 20μg/m and 40μg/m, for both pollutants, respectively. In the two-pollutant-adjusted models, an interquartile range (IQR) increase of 14.2μg/m in NO was associated with an increased risk of new onset of ocular-nasal symptoms (adjusted odds ratio-aOR: 1.63, 95% CI: 1.01-2.60), wheezing (aOR: 3.57, 95% CI: 1.18-10.92), more than two or more asthma symptom score (aOR: 1.71, 95% CI: 1.02-2.86), and airway inflammation defined as FeNO > 35 ppb (aOR: 3.10, 95% CI: 1.10-8.71), independent of PM exposures.
This study provided evidence that ambient NO levels below local standards and international guidelines, independent of PM exposure, increases new cases of asthma-associated outcomes after 12-months.
以前没有流行病学研究调查过长期环境二氧化氮（NO）和直径 2.5 微米颗粒物（PM）暴露与非洲学童哮喘结果之间的联合关联。
本研究调查了长期暴露于环境空气污染物对南非西开普省一个学童队列中哮喘相关结局的独立和共同污染物关联。
共有 590 名居住在四个非正规住区的四年级学生参与了研究。在基线和 12 个月随访时，对学生进行了肺活量测定和呼出气一氧化氮（FeNO）测量，同时向照顾者发放了标准化问卷。使用土地利用回归模型为每个孩子的家庭估算了年度 NO 和 PM 水平。构建了单污染物和双污染物模型，以评估两种空气污染物（NO 和 PM）对新的哮喘相关结局的独立和共同污染物关联，同时调整了宿主特征、室内暴露和研究区域。
四个研究区域的 PM 和 NO 年平均浓度分别为 10.01μg/m 和 16.62μg/m，均低于当地 20μg/m 和 40μg/m 的标准，分别为两种污染物。在双污染物调整模型中，NO 增加 14.2μg/m 的四分位间距（IQR）与眼部-鼻部症状新发病例（调整后的优势比-aOR：1.63，95%可信区间：1.01-2.60）、喘息（aOR：3.57，95%可信区间：1.18-10.92）、哮喘症状评分大于等于两次或更多（aOR：1.71，95%可信区间：1.02-2.86）以及 FeNO 大于 35 ppb 定义的气道炎症（aOR：3.10，95%可信区间：1.10-8.71）的风险增加相关，而与 PM 暴露无关。
本研究提供了证据表明，在低于当地标准和国际指南的环境 NO 水平下，与 PM 暴露无关，可在 12 个月后增加新的哮喘相关结局。
