title: Short-term increase in particulate matter blunts nocturnal blood pressure dipping and daytime urinary sodium excretion.
abstract: Short-term exposure to ambient particulate matter with aerodynamic diameters<10 µm were found to be positively associated with blood pressure. Yet, little information exists regarding the association between particles and circadian rhythm of blood pressure. Hence, we analyzed the association of exposure to particulate matter with aerodynamic diameters<10 µm on the day of examination and ≤7 days before with ambulatory blood pressure and with sodium excretion in 359 adults from the general population using multiple linear regression. After controlling for potential confounders, a 10-µg/m3 increase in particulate matter with aerodynamic diameters<10 µm levels was associated with nighttime systolic blood pressure (β=1.32 mm Hg 95% CI, 0.06-2.58 mm Hg at lag 0; P=0.04), nighttime diastolic blood pressure (0.72 mm Hg 95% CI, 0.03-1.42 mm Hg at lag 2; P=0.04), nocturnal systolic blood pressure dipping (-0.96 mm Hg 95% CI, -1.89 to -0.03 mm Hg at lag 0; P=0.044), and daytime urinary sodium excretion (-0.05 log-mmol/min 95% CI, -0.10 to -0.01 log-mmol/min at lag 0; P=0.027) but not with nighttime sodium excretion. The associations with blood pressure rapidly diminished with increasing lag days, and the associations with daytime sodium excretion were maximal with particulate matter with aerodynamic diameters<10 µm in exposures 2 to 5 days before. The associations of short-term increases in particulate matter with aerodynamic diameters<10 µm with higher nighttime blood pressure and blunted systolic blood pressure dipping were preceded by associations with reduced ability of the kidney to excrete sodium during daytime. The underlying mechanism linking air pollution to increased cardiovascular risk may include disturbed circadian rhythms of renal sodium handling and blood pressure.
authors.affiliation: Institute of Social and Preventive Medicine, Department of Medicine, Lausanne University Hospital, Biopôle 2, Route de la Corniche 10, CH-1010 Lausanne, Switzerland.
authors.forename: Dai-Hua
authors.initials: DH
authors.lastname: Tsai
authors.forename: Michael
authors.initials: M
authors.lastname: Riediker
authors.forename: Grégoire
authors.initials: G
authors.lastname: Wuerzner
authors.forename: Marc
authors.initials: M
authors.lastname: Maillard
authors.forename: Pedro
authors.initials: P
authors.lastname: Marques-Vidal
authors.forename: Fred
authors.initials: F
authors.lastname: Paccaud
authors.forename: Peter
authors.initials: P
authors.lastname: Vollenweider
authors.forename: Michel
authors.initials: M
authors.lastname: Burnier
authors.forename: Murielle
authors.initials: M
authors.lastname: Bochud
mesh_terms: D000328:Adult; D000368:Aged; D000393:Air Pollutants / Q000633:toxicity*; D001794:Blood Pressure / Q000502:physiology*; D018660:Blood Pressure Monitoring, Ambulatory; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D052638:Particulate Matter; D012964:Sodium / Q000652:urine*
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D012964:Sodium