title: Particulate matter air pollution and ambient temperature: opposing effects on blood pressure in high-risk cardiac patients.
abstract: OBJECTIVE
  Fine particulate matter air pollution (PM2.5) and extreme temperatures have both been associated with alterations in blood pressure (BP). However, few studies have evaluated their joint haemodynamic actions among individuals at high risk for cardiovascular events.
  
  
  METHODS
  We assessed the effects of short-term exposures during the prior week to ambient PM2.5 and outdoor temperature levels on resting seated BP among 2078 patients enrolling into a cardiac rehabilitation programme at the University of Michigan (from 2003 to 2011) using multiple linear regression analyses adjusting for age, sex, BMI, ozone and the same-day alternate environmental factor (i.e. PM2.5 or temperature).
  
  
  RESULTS
  Mean PM2.5 and temperature levels were 12.6 ± 8.2 μg/m and 10.3 ± 10.4°C, respectively. Each standard deviation elevation in PM2.5 concentration during lag days 4-6 was associated with significant increases in SBP (2.1-3.5 mmHg) and DBP (1.7-1.8 mmHg). Conversely, higher temperature levels (per 10.4°C) during lag days 4-6 were associated with reductions in both SBP (-3.6 to -2.3 mmHg) and DBP (-2.5 to -1.8 mmHg). There was little evidence for consistent effect modification by other covariates (e.g. demographics, seasons, medication usage).
  
  
  CONCLUSIONS
  Short-term exposures to PM2.5, even at low concentrations within current air quality standards, are associated with significant increases in BP. Contrarily, higher ambient temperatures prompt the opposite haemodynamic effect. These findings demonstrate that both ubiquitous environmental exposures have clinically meaningful effects on resting BP among high-risk cardiac patients.
authors.affiliation: aDepartment of Life, Health and Environmental Sciences, Division of Internal Medicine and Nephrology, University of L'Aquila, L'Aquila, Italy bDivision of Cardiovascular Medicine cDepartment of Biostatistics, School of Public Health dDepartment of Environmental Health Sciences, University of Michigan, Ann Arbor eAir Quality Division, Michigan, Department of Environmental Quality, Lansing, Michigan, USA.
authors.forename: Paolo
authors.initials: P
authors.lastname: Giorgini
authors.forename: Melvyn
authors.initials: M
authors.lastname: Rubenfire
authors.forename: Ritabrata
authors.initials: R
authors.lastname: Das
authors.forename: Theresa
authors.initials: T
authors.lastname: Gracik
authors.forename: Lu
authors.initials: L
authors.lastname: Wang
authors.forename: Masako
authors.initials: M
authors.lastname: Morishita
authors.forename: Robert L
authors.initials: RL
authors.lastname: Bard
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Jackson
authors.forename: Craig A
authors.initials: CA
authors.lastname: Fitzner
authors.forename: Claudio
authors.initials: C
authors.lastname: Ferri
authors.forename: Robert D
authors.initials: RD
authors.lastname: Brook
mesh_terms: D000368:Aged; D000393:Air Pollutants; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000503:physiopathology; D003430:Cross-Sectional Studies; D004781:Environmental Exposure / Q000032:analysis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D052638:Particulate Matter; D012307:Risk Factors; D013696:Temperature
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter