Blood markers of inflammation and coagulation and exposure to airborne particles in employees in the Stockholm underground

¹ Dept. Public Health, Karolinska Institutet, Sweden
² Dept. Occupational and Environmental Health, Stockholm Centre for Public Health, Sweden
³ Institute of Environmental Medicine, Karolinska Institutet, Sweden

^* To whom correspondence should be addressed. E-mail: carolina.bigert{at}sll.se.

Accepted 14 December 2007

	Abstract

Objectives: Although associations have been found between levels of ambient airborne particles and cardiovascular disease (CVD) in the general population, little is known about possible cardiovascular effects from high exposure to particles prevailing in underground railway systems. This led us to investigate risk markers for CVD in employees exposed to particles in the Stockholm underground system.

Methods: Seventy-nine workers in the Stockholm underground were investigated between November 2004 and March 2005. All were non-smokers in the age range 25–50; 54 were men and 25 were women. Three exposure groups were delineated: 29 platform workers with high exposure to particles, 29 train drivers with medium exposure, and 21 ticket sellers with low exposure (control group). A baseline blood sample was taken after two days of vacation, and a second sample after two working days, for analysis of levels of plasminogen activator inhibitor-1 (PAI-1), high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), fibrinogen, von Willebrand factor and factor VII. We investigated changes in plasma concentrations between sample 1 and sample 2, and differences in average concentrations between the groups.

Results: No changes between sample 1 and 2 were found that could be attributed to the particle exposure. However, the highly exposed platform workers were found to have higher plasma concentrations of PAI-1 and hs-CRP than the ticket sellers and train drivers. This suggests that there could be a long-term inflammatory effect of the particle exposure. These differences remained for PAI-1 in the comparison between platform workers and ticket sellers after adjusting for body mass index (BMI).

Conclusions: Employees who were highly exposed to airborne particles in the Stockholm underground tended to have elevated levels of risk markers of CVD relative to employees with low exposure. However, the differences observed cannot be linked to the particle exposure as such with certainty.

Keywords: air pollutants, cardiovascular, haematological effects, occupation, subway

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