Long term monitoring of organic source indicators on a daily basis at the aerosol field station of the Helmholtz Zentrum München at Augsburg City: Application for epidemiological research
J. Schnelle-Kreis (HMGU / CMA), A. Peters (HMGU / EPI), H.-E. Wichmann (HMGU / EPI), U. Küpper (HMGU / EPI), J. Orasche (HMGU / CMA), G. Seibert (HMGU / CMA), R. Zimmermann (UR / HMGU)
- Fig. 1: Aerosol Field Station of the HMGU at Augsburg University of Applied Sciences. In the foreground the measuring container of the Institute of Epidemiology can be seen. In the background is the measuring container of the cooperation group “Complex Molecular Analytics.”
Numerous epidemiological studies have shown associations between atmospheric particulate matter and cardiovascular mortality and morbidity. Most notably, these studies investigate the effects of fine (< 2.5 microns) and ultrafine (< 0.1 microns) particles in the air. The concentration of these particles in the air could directly be related to heart rate variability, blood pressure and inflammatory markers. Cardiovascular diseases are frequently associated with symptoms like shortness of breath, chest pain or the avoidance of physical activity caused by heart problems. While these cardiorespiratory symptoms may occur frequently and significantly reduce the quality of life of those affected, the impact of these particles has largely been overlooked in epidemiological investigations.
The EU-funded ULTRA study (Exposure and Risk Assessment for Fine and Ultrafine Particles in Ambient Air) reported an association between the appearance of several cardiorespiratory symptoms and the mass concentration of fine particles. However, it is unclear which particle properties are responsible for the observed effects.
The objective of other epidemiological studies was to identify various source-specific fractions that are responsible for health effects, using the elemental composition of the particles. These studies indicate that in particular, particles from combustion processes and traffic emissions may have a major impact on human health. However, the source identification based on the analysis of inorganic components bears many uncertainties. A significantly improved source apportionment, especially for combustions aerosols may be achieved by selectively analysing the organic aerosol constituents. For example, traffic emissions (in particular unburned lubrication oil) and the combustion of coal can be distinguished by patterns in the substance group of hopanes. Direct health effects of hopanes, however, have not been verified. By contrast, the clearly carcinogenic polycyclic aromatic hydrocarbons (PAHs) are suited only to a limited degree for the characterization of various sources of combustion aerosols.
Given the documented similarities of the mechanisms promoting the development of cancer and atherosclerosis, it is assumed that PAHs can also have cardiovascular effects. Animal experiments have revealed that benzo[a]pyrene may possibly accelerate atherosclerosis by triggering inflammatory processes. To what extent PAHs are involved in short-term effects of particles on the cardiovascular system has not yet been investigated.
To provide a basis for epidemiological studies and to improve the source identification on the basis of organic compounds in aerosol, daily PM2.5 samples of particulate matter have been collected since late summer 2002 at the aerosol field station of the HMGU (Fig. 1). For the analysis of the samples, a method was developed to routinely carry out the quantification of more than 200 organic components on a daily basis. The direct Thermal Desorption Gas Chromatography – Time-of-Flight Mass Spectrometry (TD-GC-TOFMS) is used to determine non-polar to moderately polar and non-volatile to semi-volatile organic compounds ([SV]OC) in the samples. The primary objective of the project is to identify the major sources of the organic components of particular matter. With the aid of the so-called positive matrix factorization, different combustion processes (traffic; domestic heating with wood, coal and fuel oil), debris of plants and photo oxidation of aerosol constituents could be identified as relevant sources.
- Fig. 2: Associations between the cardiovascular symptoms „chest pain“ (upper), “Avoidance of physical activity” (middle) and shortness of breath (lower) and concentrations of PAHs and selected hopanes on the same day (lag0) until three days after exposure (lag3)
The EU-funded AIRGENE study (Air pollution and Inflammatory Response in myocardial infarction survivors: Gene-Environment interaction in a high risk group) examines, among others, the impact of hopanes and PAHs on cardiovascular symptoms of heart attack survivors. The avoidance of physical activity due to heart problems increased on the day of exposure in correlation with most of the hopanes from traffic emissions and with the PAHs (e.g., 10% per 1.08 ng m-3 increase in benzo[a]anthracen, 95% confidence interval (CI) 2%-19%). The symptom decreased significantly with a lag of one or tow days, respectively (Fig. 2). A more frequent occurrence of shortness of breath was associated with most of the hopanes and all PAHs three days after exposure (e.g., 10% per 0.21 ng m-3 increase in 17α(H),21β(H)-30-norhopane, 95% CI 2%-19%). Yet the results are also indicative of an immediate decrease in shortness of breath in association with several PAHs and of a delayed decrease by one or two days, in association with hopanes (Fig. 2). The results did not show an association between the appearance of chest pain and hopane or PAH concentration.
To what extent hopanes and/or PAHs are involved in the observed effects or whether they are only indicators of other particle properties not listed here could not yet be clarified in this study. For this purpose, further studies are required. They will be carried out within the framework of program-oriented funding (POF II) in the project area NanoHealth and will be supported by third-party funds.
