Association of Ozone Exposure With Cardiorespiratory Pathophysiologic Mechanisms in Healthy Adults

Abstract

IMPORTANCE Exposure to ozone has been associated with cardiovascular mortality, but the underlying biological mechanisms are not yet understood.OBJECTIVE To examine the association between ozone exposure and cardiopulmonary pathophysiologic mechanisms. DESIGN, SETTING, AND PARTICIPANTSA longitudinal study involving 89 healthy adult participants living on a work campus in Changsha City, China, was conducted from December 1, 2014, to January 31, 2015. This unique quasiexperimental setting allowed for better characterization of air pollutant exposure effects because the participants spent most of their time in controlled indoor environments. Concentrations of indoor and outdoor ozone, along with the copollutants particulate matter, nitrogen dioxide, and sulfur dioxide, were monitored throughout the study period and then combined with time-activity information and filtration conditions of each residence and office to estimate 24-hour and 2-week combined indoor and outdoor mean exposure concentrations. Associations between each exposure measure and outcome measure were analyzed using single-pollutant and 2-pollutant linear mixed models controlling for ambient temperature, secondhand smoke exposure, and personal-level time-varying covariates.MAIN OUTCOMES AND MEASURES Biomarkers indicative of inflammation and oxidative stress, arterial stiffness, blood pressure, thrombotic factors, and spirometry were measured at 4 sessions. RESULTSOf the 89 participants, 25 (28%) were women and the mean (SD) age was 31.5 (7.6) years. The 24-hour ozone exposure concentrations ranged from 1.4 to 19.4 parts per billion (ppb), corresponding to outdoor concentrations ranging from 4.3 to 47.9 ppb. Within this range, in models controlling for a second copollutant and other potential confounders, a 10-ppb increase in 24-hour ozone was associated with mean increases of 36.3% (95% CI, 29.9%-43.0%) in the level of platelet activation marker soluble P-selectin, 2.8% (95% CI, 0.6%-5.1%) in diastolic blood pressure, 18.1% (95% CI, 4.5%-33.5%) in pulmonary inflammation markers fractional exhaled nitric oxide, and 31.0% (95% CI, 0.2%-71.1%) in exhaled breath condensate nitrite and nitrate as well as a −9.5% (95% CI, −17.7% to −1.4%) decrease in arterial stiffness marker augmentation index. A 10-ppb increase in 2-week ozone was associated with increases of 61.1% (95% CI, 37.8%-88.2%) in soluble P-selectin level and 126.2% (95% CI, 12.1%-356.2%) in exhaled breath condensate nitrite and nitrate level. Other measured biomarkers, including spirometry, showed no significant associations with either 24-hour ozone or 2-week ozone exposures.CONCLUSIONS AND RELEVANCE Short-term ozone exposure at levels not associated with lung function changes was associated with platelet activation and blood pressure increases, suggesting a possible mechanism by which ozone may affect cardiovascular health.

Combined use of an electrostatic precipitator and a high-efficiency particulate air filter in building ventilation systems: Effects on cardiorespiratory health indicators in healthy adults

“…Based on the same field study, we previously evaluated associations between pollutant exposures and biomarker outcomes. 6 We found significant associations of either 24-hour O 3 exposure or 2-week O 3 exposure with a biomarker of platelet activation (plasma-soluble P-selectin) and systolic blood pressure, suggesting that O 3 exposure may increase cardiovascular disease risk via blood pro-coagulation and blood pressure increases. The aim of this study was to examine the impact of temporarily removing either ESPs alone or both ESPs and HEPA filters from the 3-part (F8-ESP-HEPA) air-handling systems on cardiorespiratory function and biomarkers reflecting cardiorespiratory pathophysiology.…”

Impact of Obesity and Ozone on the Association Between Particulate Air Pollution and Cardiovascular Disease and Stroke Mortality Among US Adults

“…105 In another study, short-term ozone exposure was linked to BP. 106 Moreover, 2 previous studies found that ozone exposure was negatively (beneficially) or not associated with BP, 80,107 but a recent study has reported a positive association between ozone and both systolic and diastolic BP measurements at slightly higher exposure concentrations. 108…”

Ozone in urban China: Impact on mortalities and approaches for establishing indoor guideline concentrations

“…It might be argued that indoor ozone exposure, although substantial, occurs at concentrations below a “health threshold.” However, recent studies do not support the presence of a threshold for short‐term mortality nor for adverse cardiorespiratory indicators …”

“…However, recent studies do not support the presence of a threshold for shortterm mortality 2,49 nor for adverse cardiorespiratory indicators. 50 When indoors, humans are exposed not only to ozone, but also to products of ozone-initiated chemistry. 20,23,36,[51][52][53][54][55][56][57][58][59][60][61][62][63][64] Some of these products (eg, hydroxyl radicals, hydrogen peroxide, organic peroxides, formaldehyde, dicarbonyls, secondary organic aerosols) potentially contribute to the total mortality associated with long-term exposure to ozone as evaluated using measured or modeled outdoor ozone concentrations.…”