Quantifying the equivalency factor between PM-absorbance and EC mass concentration – converting the “old” exposure proxy in large health studies to the new metric for diesel soot

IF 2.9 4区环境科学与生态学 Q3 ENVIRONMENTAL SCIENCES

Air Quality Atmosphere and Health Pub Date : 2025-05-06 DOI:10.1007/s11869-025-01741-4

Harry ten Brink, Gerard Hoek, Regina Hitzenberger

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引用次数: 0

Abstract

The light absorbance of PM-samples on PTFE filters is often used as a measure for exposure to diesel soot in large-scale health studies. Absorbance is a synonym for the optical parameter “absorption coefficient” (AbsC). The formal exposure measure for diesel soot is the mass concentration of the light absorbing species of PM, viz. elemental carbon (EC). In the central health effects study by Janssen et al. [2011] a relation between AbsC and EC is presented, however with an overall uncertainty of 2.5. In the present study, we started with an analysis of the measuring approach of light absorption according to ISO-9835 [ISO, 1993]. Following this procedure, absorption is probed in reflection and expressed in the ratio of the intensity of light reflected from/by a clean and a loaded filter. The AbsC is the logarithm of this ratio (which is known as optical depth) scaled to the volume of air sampled and loaded filter area. We first critically reanalysed the studies used by Janssen et al. [2011] in which the equivalency factor between absorbance and EC concentration was given. We found a good linear relationship when we selected only those data points for which the optical density (OD) was within the proper limits of 0.05 and 2.0. We then analysed which methods had been used to obtain EC data in those studies (and also more recent ones) and selected only those studies where EC had been determined with an official reference approach, i.e. the USreference method NIOSH-5400. The overall relation of EC mass concentration in µg m⁻³ and AbsC in units of 10^–5 m⁻¹ was 0.8 (R² = 0.92), or 1.0 according to the EU-reference method EUSAAR2-TOT with a factor of 1.25 between US and EU reference EC values. This highly improved estimate of equivalence factors between AbsC and EC might be used to translate the results of existing health effects studies (based on AbsC) to studies using current EC monitoring data (as prescribed in EU-guidelines for air quality) to investigate the possible health effects at a given EC level.

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量化pm吸光度与EC质量浓度之间的等效因子——将大型健康研究中的“旧”暴露代理转换为柴油烟尘的新度量

在大规模的健康研究中，聚四氟乙烯过滤器上的pm样品的光吸收率经常被用作柴油烟灰暴露的测量。吸光度是光学参数“吸收系数”（AbsC）的同义词。柴油烟尘的正式暴露量是PM的吸光物质即单质碳（EC）的质量浓度。在Janssen等人[2011]的中心健康影响研究中，提出了AbsC和EC之间的关系，但总体不确定性为2.5。在本研究中，我们首先根据ISO-9835 [ISO， 1993]分析了光吸收的测量方法。按照这个程序，吸收是在反射中探测的，并以从干净的过滤器和负载的过滤器反射的光强度之比表示。AbsC是该比率（称为光学深度）的对数，按比例缩放到空气采样和加载过滤面积的体积。我们首先批判性地重新分析了Janssen等人[2011]使用的研究，其中给出了吸光度和EC浓度之间的等效系数。当我们只选择光密度（OD）在0.05和2.0的适当范围内的数据点时，我们发现了良好的线性关系。然后，我们分析了在这些研究（以及最近的研究）中使用哪些方法获得EC数据，并仅选择了那些使用官方参考方法（即美国参考方法NIOSH-5400）确定EC的研究。µg m−3的EC质量浓度与10-5 m−1单位的AbsC的总体关系为0.8 (R2 = 0.92)，根据欧盟参考方法EUSAAR2-TOT为1.0，美国和欧盟参考EC值之间的系数为1.25。这一高度改进的对有机碳和有机碳等效系数的估计可用于将现有健康影响研究的结果（基于有机碳）转化为使用当前有机碳监测数据（按照欧盟空气质量指南的规定）的研究，以调查在给定的有机碳水平下可能产生的健康影响。

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来源期刊

Air Quality Atmosphere and Health ENVIRONMENTAL SCIENCES-

CiteScore

8.80

自引率

2.00%

发文量

146

审稿时长

>12 weeks

期刊介绍： Air Quality, Atmosphere, and Health is a multidisciplinary journal which, by its very name, illustrates the broad range of work it publishes and which focuses on atmospheric consequences of human activities and their implications for human and ecological health. It offers research papers, critical literature reviews and commentaries, as well as special issues devoted to topical subjects or themes. International in scope, the journal presents papers that inform and stimulate a global readership, as the topic addressed are global in their import. Consequently, we do not encourage submission of papers involving local data that relate to local problems. Unless they demonstrate wide applicability, these are better submitted to national or regional journals. Air Quality, Atmosphere & Health addresses such topics as acid precipitation; airborne particulate matter; air quality monitoring and management; exposure assessment; risk assessment; indoor air quality; atmospheric chemistry; atmospheric modeling and prediction; air pollution climatology; climate change and air quality; air pollution measurement; atmospheric impact assessment; forest-fire emissions; atmospheric science; greenhouse gases; health and ecological effects; clean air technology; regional and global change and satellite measurements. This journal benefits a diverse audience of researchers, public health officials and policy makers addressing problems that call for solutions based in evidence from atmospheric and exposure assessment scientists, epidemiologists, and risk assessors. Publication in the journal affords the opportunity to reach beyond defined disciplinary niches to this broader readership.