title: Systemic effects of controlled exposure to diesel exhaust: a meta-analysis from randomized controlled trials.
abstract: Ambient air pollution is associated with adverse cardiovascular events. This meta-analysis aimed to investigate the short-term association between air pollution and cardiovascular effects on healthy volunteers.
  
  
  
  We searched databases to identify randomized trials with controlled human exposures to either of two models for studying ambient particulate matter: diesel-exhaust or concentrated ambient particles. Estimates of size effect were performed using standardized mean difference (SMD). Heterogeneity was assessed with I2statistics. Outcomes were vascular function estimated by forearm blood flow (FBF), blood pressure, heart rate, and blood analysis.
  
  
  
  Database searches yielded 17 articles (n = 342) with sufficient information for meta-analyses. High levels of heterogeneity for the some outcomes were analyzed using random-effects model. The pooled effect estimate showed that short-term exposure to air pollution impaired FBF response from 2.7 to 2.5 mL/100 mL tissue/min (SMD 0.404; p = .006). There was an increase in 5000 platelet/mm3following pollution exposure (SMD 0.390; p = .050) but no significant differences for other outcomes.
  
  
  
  Controlled human exposures to air pollution are associated with the surrogates of vascular dysfunction and increase in platelet count, which might be related to adverse cardiovascular events. Given the worldwide prevalence of exposure to air pollution, these findings are relevant for public health. KEY MESSAGES Controlled exposure to air pollution impairs vasomotor response, which is a surrogate for adverse cardiovascular events. This is the first meta-analysis from randomized clinical trials showing short-term association between air pollution and cardiovascular effects on healthy volunteers. Given the worldwide prevalence of exposure to air pollution, this finding is important for public health.
authors.affiliation: a Department of Heart Failure , Heart Institute (InCor), University of Sao Paulo Medical School , Sao Paulo , Brazil.
authors.forename: Jefferson Luis
authors.initials: JL
authors.lastname: Vieira
authors.affiliation: b Department of Cardiology, Baylor College of Medicine , Houston , TX , USA.
authors.forename: Francisco Yuri
authors.initials: FY
authors.lastname: Macedo
authors.affiliation: c Department of Cardiology , Pima Heart Institute , Tucson , AZ , USA.
authors.forename: Alexandre Miguel
authors.initials: AM
authors.lastname: Benjo
authors.affiliation: a Department of Heart Failure , Heart Institute (InCor), University of Sao Paulo Medical School , Sao Paulo , Brazil.
authors.forename: Guilherme V
authors.initials: GV
authors.lastname: Guimarães
authors.affiliation: d Department of Cardiology , Heart and Failure Transplant, Mount Sinai Hospital , New York , NY , USA.
authors.forename: Johanna Paola
authors.initials: JP
authors.lastname: Contreras
authors.affiliation: a Department of Heart Failure , Heart Institute (InCor), University of Sao Paulo Medical School , Sao Paulo , Brazil.
authors.forename: Edimar A
authors.initials: EA
authors.lastname: Bocchi
mesh_terms: D000293:Adolescent; D000328:Adult; D000397:Air Pollution / Q000009:adverse effects*; D002318:Cardiovascular Diseases / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D052638:Particulate Matter / Q000506:poisoning*; D016032:Randomized Controlled Trials as Topic; D001335:Vehicle Emissions / Q000506:poisoning*; D055815:Young Adult
chemical_list: D052638:Particulate Matter; D001335:Vehicle Emissions
keywords: Air pollution; cardiovascular diseases; meta-analysis