Exposure to airborne particles is a risk factor of many short- and long-term health effects. Most epidemiological studies include estimates of exposure to ambient particles, however, people living in developed countries spend most of their time indoors. This work presents an analysis of a field campaign of simultaneous measurements of indoor-to-outdoor particle number concentrations (PNCs) in Israel. Fine and coarse PNCs were continuously measured using Dylos DC1700 devices from October 2016 to October 2017. The median outdoor PNC was always higher than the indoor PNC in all the five sampling locations. Outdoor fine PNCs peak during the night and experience a trough in the afternoon. The median of the fine indoor-to-outdoor PNC ratio (IOR) was 0.83, with an inter quartile range (IQR) of 0.59. The median of the coarse IOR was 0.70, with an IQR of 0.77. Lower IORs were experienced at night than during the day, with a daily peak (IOR >1) around noon. Information about the IOR in different regions and seasons may help epidemiologists and policy makers understand the true health effects of particulate air pollution, and correct their exposure estimations such that they account for indoor exposure as well.

中文翻译：

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以色列室内/室外粒子数浓度比的预测因子

暴露在空气中的颗粒是许多短期和长期健康影响的危险因素。大多数流行病学研究都包括对周围颗粒物暴露的估计，但是，发达国家的人们大部分时间都在室内度过。这项工作提出了一项对以色列室内到室外颗粒物浓度同时测量的野外运动的分析。从2016年10月至2017年10月，使用Dylos DC1700设备连续测量了精细和粗略的PNC。在所有五个采样位置中，室外PNC的中值始终高于室内PNC。户外优质PNC在夜间达到顶峰，在下午经历低谷。优良的室内外PNC比（IOR）的中位数为0.83，四分位间距（IQR）为0.59。粗略IOR的中位数为0.70，IQR为0。77.晚上的IOR比白天的要低，中午时分的每日峰值（IOR> 1）。有关不同地区和季节的IOR的信息可以帮助流行病学家和政策制定者了解颗粒物空气污染的真实健康影响，并更正其暴露估算，以便他们也考虑室内暴露。