Fine particle components and health--a systematic review and meta-analysis of epidemiological time series studies of daily mortality and hospital admissions

J Expo Sci Environ Epidemiol. 2015 Mar-Apr;25(2):208-14. doi: 10.1038/jes.2014.63. Epub 2014 Sep 17.


Short-term exposure to fine particle mass (PM) has been associated with adverse health effects, but little is known about the relative toxicity of particle components. We conducted a systematic review to quantify the associations between particle components and daily mortality and hospital admissions. Medline, Embase and Web of Knowledge were searched for time series studies of sulphate (SO4(2-)), nitrate (NO3(-)), elemental and organic carbon (EC and OC), particle number concentrations (PNC) and metals indexed to October 2013. A multi-stage sifting process identified eligible studies and effect estimates for meta-analysis. SO4(2-), NO3(-), EC and OC were positively associated with increased all-cause, cardiovascular and respiratory mortality, with the strongest associations observed for carbon: 1.30% (95% CI: 0.17%, 2.43%) increase in all-cause mortality per 1 μg/m(3). For PNC, the majority of associations were positive with confidence intervals that overlapped 0%. For metals, there were insufficient estimates for meta-analysis. There are important gaps in our knowledge of the health effects associated with short-term exposure to particle components, and the literature also lacks sufficient geographical coverage and analyses of cause-specific outcomes. The available evidence suggests, however, that both EC and secondary inorganic aerosols are associated with adverse health effects.

Publication types

  • Meta-Analysis
  • Review
  • Systematic Review

MeSH terms

  • Aerosols / adverse effects
  • Air Pollutants / adverse effects*
  • Air Pollution / adverse effects
  • Carbon / adverse effects
  • Cardiovascular Diseases / mortality*
  • Databases, Factual
  • Hospitalization
  • Humans
  • Lung Diseases / mortality*
  • Nitrates / adverse effects
  • Particle Size
  • Particulate Matter / adverse effects*
  • Sulfates / adverse effects
  • Time Factors


  • Aerosols
  • Air Pollutants
  • Nitrates
  • Particulate Matter
  • Sulfates
  • Carbon