Health Effects of Ultrafine Particles – Systematic Literature Research of Epidemiologic Studies and its Transferability to the German Context

Up to now, regulations on the concentration of ultrafine particles (UFP; particles with a diameter of less than 100 nm) are lacking. In contrast to larger particles, UFPs originate from different sources and vary with regard to their chemical composition and physical reactivity. Due to their small size, inhaled UFPs may enter into alveoli and are even capable to penetrate cell membranes. Consequently, UFPs may pass into the blood system, overcome the placental barrier, and finally diffuse into all organ systems, including the brain and nervous system. Toxicological studies suggest that UFPs contribute to the development and progression of various diseases (HEI 2013).

Epidemiological evidence for health effects of UFPs, in comparison to that for larger particles, is scarce. Nevertheless, numerous studies have been published in the last decade. Several expert committees have reviewed and interpreted the epidemiological evidence base concerning UFPs (HEI 2013 (Health Effects Institute, Boston), WHO 2013), and the expert commission of the HEI and of the WHO concluded that scientific studies suggest harmful effects of UFPs on health. However, particularly in terms of epidemiologic studies, the evidence base was not sufficient to recommend regulations on UFP exposure concentrations. Recently published epidemiologic studies now make it necessary to reevaluate the evidence base on the health effects of UFPs.


  • To conduct a systematic literature search and review of articles addressing adverse health effects of UFPs.
  • To evaluate the role of co-pollutant adjustment in the available literature.
  • To evaluate the transferability of the results to the German situation.

Study design

Systematic review accoring to PRISMA guidelines

FundingUmweltbundesamt FKZ 00377 7205
Duration31.1.2017 – 31.01.2018
TeamBarbara Hoffmann (PI), Simone Ohlwein, Anna Buschka
External collaboratorsRon Kappeler, Nino Künzli (Swiss TPH)

Main report

Ohlwein S, Hoffmann B, Kappeler R, Joss MK, Künzli N. Health Effects of Ultrafine Particles - Systematic literature search and the potential transferability of the results to the German setting; 2018. UMWELT & GESUNDHEIT; 05/2018.


  • Ohlwein S, Kappeler R, Kutlar Joss M, Künzli N, Hoffmann B. Health effects of ultrafine particles: a systematic literature review update of epidemiological evidence. Int J Public Health. 2019;64(4):547-559. doi:10.1007/s00038-019-01202-7.


  • Health Effects Institute. Understanding the Health Effects of Ambient Ultrafine Particles. Boston, Massachusetts; 2013. HEI Perspectives; 3.

  • WHO. Review of evidence on health aspects of air pollution – REVIHAAP Project: Technical Report; 2013.


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