Division of Environmental Health Sciences, Wadsworth Center, New York State Department of Health, Empire State Plaza, Albany, NY 12237, United States; Department of Environmental Health Sciences, School of Public Health, University at Albany, Albany, NY, United States.
Department of Community Health Sciences, The Aga Khan University, Karachi, Pakistan.
Sci Total Environ. 2024 Sep 10;942:173403. doi: 10.1016/j.scitotenv.2024.173403. Epub 2024 Jun 4.
With 24 million inhabitants and 6.6 million vehicles on the roads, Karachi, Pakistan ranks among the world's most polluted cities due to high levels of fine particulate matter (PM). This study aims to investigate PM mass, seasonal and temporal variability, chemical characterization, source apportionment, and health risk assessment at two urban sites in Karachi. Samples were analyzed using ion chromatography and dual-wavelength optical transmissometer for various inorganic components (anions, cations, and trace elements) and black carbon (BC). Several PM pollution episodes were frequently observed, with annual mean concentrations at Kemari (140 ± 179 μg/m) and Malir (95 ± 40.9 μg/m) being significantly above the World Health Organization's guidelines of 5 μg/m. Chemical composition at both sites exhibited seasonal variability, with higher pollution levels in winter and fall and lower concentrations in summer. The annual average BC concentrations were 4.86 ± 5.29 μg/m and 4.52 ± 3.68 μg/m, respectively. A Positive Matrix Factorization (PMF) analysis identified 5 factors, crustal, sea salt, vehicular exhaust, fossil-fuel combustion, and industrial emission. The health risk assessment indicated a higher number of deaths in colder seasons (fall and winter) at the Kemari (328,794 and 287,814) and Malir (228,406 and 165,737) sites and potential non-carcinogenic and carcinogenic risks to children from metals. The non-carcinogenic risk of PM bound Pb, Fe, Zn, Mn, Cr, Cu and Ni via inhalation exposure were within the acceptable level (<1) for adults. However, potential non-carcinogenic and carcinogenic health risk posed by Pb and Cr through inhalation were observed for children. The findings exhibit critical levels of air pollution that exceed the safe limits in Karachi, posing significant health risks to children and sensitive groups. Our study underscores the urgent need for effective emission control strategies and policy interventions to mitigate these air pollution risks.
卡拉奇是巴基斯坦的一个拥有 2400 万居民和 660 万辆汽车的城市，由于细颗粒物 (PM) 水平较高，它被列为世界上污染最严重的城市之一。本研究旨在调查卡拉奇两个城区的 PM 质量、季节性和时间变化、化学特征、源解析和健康风险评估。使用离子色谱法和双波长光透射计分析样品，以测量各种无机成分（阴离子、阳离子和微量元素）和黑碳 (BC)。经常观察到几个 PM 污染事件，Kemari（140±179μg/m）和 Malir（95±40.9μg/m）的年平均浓度明显高于世界卫生组织规定的 5μg/m。两个站点的化学成分均表现出季节性变化，冬季和秋季污染水平较高，夏季浓度较低。年平均 BC 浓度分别为 4.86±5.29μg/m 和 4.52±3.68μg/m。正定矩阵因子分析 (PMF) 识别出 5 种因子，分别为地壳、海盐、机动车尾气、化石燃料燃烧和工业排放。健康风险评估表明，Kemari（328,794 和 287,814）和 Malir（228,406 和 165,737）站点在较冷的季节（秋季和冬季）死亡人数较多，并且金属对儿童存在潜在的非致癌和致癌风险。通过吸入暴露，PM 结合 Pb、Fe、Zn、Mn、Cr、Cu 和 Ni 的非致癌风险对成年人低于可接受水平（<1）。然而，通过吸入，Pb 和 Cr 对儿童的非致癌和致癌健康风险仍然存在。研究结果表明，卡拉奇的空气污染程度严重超标，对儿童和敏感群体构成重大健康风险。我们的研究强调了迫切需要采取有效的排放控制策略和政策干预措施，以减轻这些空气污染风险。
