Assessing health risks associated with exposure to household and ambient air pollution in rural and urban China

空气污染是全世界健康不良的一个重要原因。在中国和许多其他发展中国家尤其如此，在这些国家，由于交通和工业活动的增加，室外空气污染正在恶化。此外，在农村地区，许多人仍然使用固体燃料（如木材、木炭或煤）做饭和取暖，在家中产生有害烟雾和其他有毒物质。虽然我们知道空气污染在人口层面上导致死亡和疾病，但由于缺乏准确的信息，我们无法完全了解其确切程度。要可靠地估计空气污染造成的疾病风险，需要测量个人接触空气污染及其随后的疾病后果（即新疾病的发病和死亡）。我们建议利用中国嘉道里生物样本库（CKB）来解决这一知识差距，这是一项大型研究，2004- 2008年从中国10个不同的城市和农村地区招募了50万名男性和女性，详细跟踪疾病结果，作为研究空气污染对健康影响的资源。这代表了一种有效的方法，避免了需要单独进行昂贵的研究来开展这项工作。以这种方式使用CKB需要改进现有的空气污染数据。与许多其他大规模流行病学研究一样，CKB并没有直接单独测量实际的空气污染水平，而是依赖于参与者报告他们用于烹饪或取暖的燃料类型以及他们居住的频率或距离主干道的远近。由于个人在不同地点从事不同活动的时间不同，这可能是对个人空气污染的不准确衡量。理想的情况是实时测量每个人呼吸的空气中的污染物浓度。然而，这在一项涉及50万参与者的研究中是不切实际的，因此挑战在于以具有成本效益的方式估算暴露量。该提案是一个试点项目，旨在测试和评估测量个人暴露于家庭和环境空气污染的不同方法。在这个项目中，我们将要求来自2个农村地区和1个城市地区的300名CKB参与者携带一个小型可穿戴监视器，记录一年中温暖季节和寒冷季节两个5天的颗粒污染物浓度。此外，我们将要求他们记录他们正在做什么活动（例如做饭、上下班）、持续时间和地点，以便我们了解他们接触的污染有多少来自室内或室外环境。由于要求每个参与者佩戴监测器可能既困难又昂贵，我们还将测试使用地面监测网络的数据并辅以卫星遥感技术来估计个人空气污染是否足够。在环绕地球运行的众多卫星中，有两颗携带着传感器，可以探测穿过大气的红外光，从而测量空气中的颗粒物。利用卫星和地面监测仪的信息，我们将绘制一幅更完整的空气污染地图。我们将在苏州测试和优化这种新方法，苏州是一个城市CKB站点，已经有很好的地面污染监测数据覆盖。根据研究参与者的居住地址，我们可以使用这张空气污染地图来估计个人的环境暴露水平。我们将利用这些信息进行分析，调查苏州市空气污染对参与者健康的影响。这项建议将提供重要的新理解和经验，以规划一个涉及所有50万CKB参与者的更大项目。我们的最终目标是收集可靠的暴露和疾病结果数据，以准确了解中国空气污染对健康的影响。

Air pollution is an important cause of ill-health worldwide. This is particularly the case in China and many other developing countries, in which outdoor air pollution is worsening due to increased traffic and industrial activities. Furthermore, many people still use solid fuels (e.g. wood, charcoal or coal) for cooking and heating in rural areas, generating harmful smoke and other toxic substances inside the home. Although we know that air pollution causes death and illness at the population level, the exact extent is not fully understood because accurate information is lacking. Reliable estimation of the disease risks arising from air pollution requires measurements of individual exposures to air pollution and their subsequent disease outcomes (i.e. onset of new diseases and death). We propose to address this knowledge gap using the China Kadoorie Biobank (CKB), a large study of 500,000 men and women recruited from 10 diverse urban and rural areas in China in 2004-08 with detailed tracking of disease outcomes as a resource to study the health effects of air pollution. This represents an efficient approach that avoids the need to generate a separate expensive study to conduct this work. Use of CKB in this way requires improvements to existing air pollution data. As in many other large scale epidemiological studies, CKB did not directly measure actual air pollution levels individually, but relied on participants to report information on the type of fuel they use for cooking or heating and how often, or how close to a main road they live. Since individuals spend a varying amount of time in different locations doing various activities, this may be inaccurate measure of individual air pollution. The ideal would be to measure in real time the pollutant concentrations in the air breathed by each person individually. However, this will be impractical in a study of 0.5 million participants, so the challenge is to achieve estimates of exposure in a cost-effective manner. This proposal represents a pilot project to test and assess different methods of measuring individual exposure to household and ambient air pollution.In this project we will ask 300 CKB participants from 2 rural and 1 urban regions to carry a small wearable monitor with them to record particle pollutant concentration for two 5 day periods in both warm and cool seasons of the year. In addition, we will ask them to note what activity (e.g. cooking, commuting) they are doing, the duration and the location, so that we can understand how much of their pollution exposure comes from indoor or outdoor environments. Because it could be difficult and expensive to ask each participant to wear a monitor, we will also test whether it is sufficient to estimate individual air pollution by using data from ground monitoring networks, supplemented by satellite remote sensing technology. Two of the many satellites orbiting Earth carry sensors that detect infrared light transmitted through the atmosphere, providing a measure of airborne particulate matter. Using information from satellites and ground monitors, we will create a more complete map of air pollution. We will test and optimise this new approach in Suzhou, an urban CKB site that already has good coverage of ground-based pollution monitoring data. Based on the residential addresses of study participants, we can use this air pollution map to estimate an individual's ambient exposure level. We will use this information to carry out an analysis to investigate the health effects of air pollution in Suzhou participants. This proposal will provide important new understanding and experience needed to plan a larger project involving all 0.5 million participants in CKB. Ultimately we aim to collect reliable exposure and disease outcome data to accurately understand the impact of air pollution on health in China.