Associations between short-term exposure to fine particulate matter (PM_2.5) and cardiovascular diseases (CVDs) have been well documented worldwide. PM_2.5 has very complex chemical compositions and it was thus crucial to determine which constituents dominate the effects of PM_2.5 on the cardiovascular system. However, investigations of the cardiovascular effects of specific constituents are scarce and limited to a small fraction of constituents, especially in developing countries.

An increasing number of studies have attempted to elucidate the time courses during which PM_2.5 exposure causes adverse cardiovascular outcomes. … As the largest developing country in the world, China is facing enormous public health challenges due to severe air pollution problems and the heavy burden of CVDs. We therefore designed this longitudinal study in Shanghai, China, to explore the short-term associations of PM_2.5 constituents on blood inflammation and coagulation, and further, to deduce which constituents are most deleterious to the cardiovascular system. Elderly patients with chronic obstructive pulmonary disease (COPD) were selected because they are hypothesized to be susceptible to the adverse cardiovascular effects of air pollutants as they have a higher deposition of particles and an inherent inflammatory state.

—Liu et al.

The research team examined the associations between 10 constituents and 10 circulating biomarkers in a panel of 28 urban residents with 4 repeated measurements in Shanghai.

During the study period 27 May to 5 July 2014), the researchers obtained real-time (hourly) concentrations of PM_2.5 and its constituents from a fixed-site monitor located on the rooftop of a 5-story building.

They linked environmental and health data by the time of blood sampling. All biomarker measurements were natural log-transformed to improve the normality before statistical analyses. They incorporated several covariates as fixed-effect terms in the analysis: (1) an indicator variable of “week” of blood collections to exclude any unknown weekly time trends; (2) an indicator variable of “day of the week” to control for the potential day-of-week effects; (3) the moving average of mean temperature and relative humidity on the current day and previous 3 days to adjust for the confounding effects of weather conditions; and (4) individual characteristics, such as age, gender, body mass index, education, and the 152 history of morbidities. A random intercept was introduced to account for the within-subject correlations due to repeated measurements.

We found significant associations between PM_2.5 and all cytokines, and these associations were restricted within 24 hours. We further identified some constituents, including OC, EC, SO₄², NO₃^-, and NH₄⁺, have more robust associations with blood inflammation or coagulation than the remaining 5 constituents. Our findings were generally insensitive to the adjustment for gaseous pollutants.

—Liu et al.

Resources

• Cong Liu, Jing Cai, Liping Qiao, Hongli Wang, Wenxi Xu, Huichu Li, Zhuohui Zhao, Renjie Chen, and Haidong Kan (2017) “The Acute Effects of Fine Particulate Matter Constituents on Blood Inflammation and Coagulation” Environmental Science & Technology doi: 10.1021/acs.est.7b00312