Kinney Patrick L, Gichuru Michael Gatari, Volavka-Close Nicole, Ngo Nicole, Ndiba Peter K, Law Anna, Gachanja Anthony, Gaita Samuel Mwaniki, Chillrud Steven N, Sclar Elliott
Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, 722 West 168th St., New York, NY 10032, USA,
Environ Sci Policy. 2011 Jun;14(4):369-378. doi: 10.1016/j.envsci.2011.02.005.
Motor vehicle traffic is an important source of particulate pollution in cities of the developing world, where rapid growth, coupled with a lack of effective transport and land use planning, may result in harmful levels of fine particles (PM(2.5)) in the air. However, a lack of air monitoring data hinders health impact assessments and the development of transportation and land use policies that could reduce health burdens due to outdoor air pollution. To address this important need, a study of traffic-related PM(2.5) was carried out in the city of Nairobi, Kenya, a model city for sub-Saharan Africa, in July 2009. Sampling was carried out using portable filter-based air samplers carried in backpacks by technicians on weekdays over two weeks at several sites in and around Nairobi ranging from high-traffic roadways to rural background. Mean daytime concentrations of PM(2.5) ranged from 10.7 at the rural background site to 98.1 μg/m(3) on a sidewalk in the central business district. Horizontal dispersion measurements demonstrated a decrease in PM(2.5) concentration from 128.7 to 18.7 μg/m(3) over 100 meters downwind of a major intersection in Nairobi. A vertical dispersion experiment revealed a decrease from 119.5 μg/m(3) at street level to 42.8 μg/m(3) on a third-floor rooftop in the central business district. Though not directly comparable to air quality guidelines, which are based on 24-hour or annual averages, the urban concentrations we observed raise concern with regard to public health and related policy. Taken together with survey data on commuting patterns within Nairobi, these results suggest that many Nairobi residents are exposed on a regular basis to elevated concentrations of fine particle air pollution, with potentially serious long-term implications for health.
在发展中世界的城市里，机动车交通是颗粒物污染的一个重要来源。在这些城市中，快速增长加上缺乏有效的交通和土地利用规划，可能导致空气中有害水平的细颗粒物（PM2.5）。然而，缺乏空气监测数据阻碍了健康影响评估以及交通和土地利用政策的制定，而这些政策本可减轻室外空气污染造成的健康负担。为满足这一重要需求，2009年7月在肯尼亚内罗毕市开展了一项与交通相关的PM2.5研究，内罗毕是撒哈拉以南非洲的一个典型城市。采样工作由技术人员在工作日背着基于滤膜的便携式空气采样器进行，为期两周，地点位于内罗毕及其周边的多个地方，从交通繁忙的道路到农村背景地区。白天PM2.5的平均浓度范围从农村背景地区的10.7 μg/m³到中央商务区人行道上的98.1 μg/m³。水平扩散测量表明，在内罗毕一个主要十字路口下风100米处，PM2.5浓度从128.7 μg/m³降至18.7 μg/m³。一项垂直扩散实验显示，在中央商务区，街道水平的浓度从119.5 μg/m³降至三楼屋顶的42.8 μg/m³。虽然我们观察到的城市浓度不能直接与基于24小时或年平均值的空气质量指南相比较，但这些浓度引发了对公众健康和相关政策的担忧。结合内罗毕通勤模式的调查数据，这些结果表明，许多内罗毕居民经常暴露于高浓度的细颗粒物空气污染中，这可能对健康产生潜在的严重长期影响。
