Mortality Risk Associated with Short-Term Exposure to Particulate Matter in China: Estimating Error and Implication

Abstract

Most previous studies used a specific size of particulate matter (PM x ) for dosimetry estimation when determining particulate matter (PM)-associated risk, which precluded the impact of other sizes of PM. Here, we used a multiple-path particle dosimetry model to determine the deposition of PM in human airways and further estimated the associated mortality risk in 205 cities in China. Results showed that the fractions of PM 1 , PM 1−2.5 , and coarse PM (PM 2.5−10 ) deposited in the tracheobronchial (TB) and pulmonary airways were estimated in ranges of 11.06−12.83, 19.9−26.37, and 5.35−9.81%, respectively. Each 10 μg/ m 3 increase in deposited PM was significantly associated with a nationwide increment of 1.12% (95% confidence interval, CI, 0.77− 1.49%) for total nonaccidental mortality. Short-term exposure to PM during 2014−2017 resulted in a nationwide mortality of 98 826 cases/ year, with contributions from PM 1 , PM 1−2.5 , coarse PM of 37.7, 43.1, and 19.2%, respectively. Our study demonstrated that the estimated mortality counts may be associated with the coefficient of variation of dosimetry estimations. In addition, we revealed the caution should be exercised when interpreting PM x -associated risk and further reinforced the importance of size distribution in relevant research.

Inhalation Bioaccessibility and Risk Assessment of Metals in PM2.5 Based on a Multiple-Path Particle Dosimetry Model in the Smelting District of Northeast China

“…The MPPD model could provide the most realistic conditions for the study population in terms of anatomy and physiology and quantify the total deposition volume and regional deposition volume of each generation of airways, and could more clearly understand the deposition rate of particulate matter in the human respiratory tract. Compared with the in vivo model, it has higher accuracy and is more convenient, and has been widely used to simulate airway deposition [ 19 , 20 , 64 ]. However, factors such as exposure scenarios, physiological input parameters, age, and gender may lead to differences in deposition fraction; thus, it is necessary to consider lung models under different conditions and parameter selection [ 19 , 64 , 65 ].…”

“…Therefore, in this study, the children were divided into 2–23 years old, and the adults were 23–96 years old. The functional residual capacity (FRC) of children and adults was calculated using a formula, which was related to the height of children, the age and height of adults [ 20 , 68 ]. The heights of different age groups were determined according to existing studies [ 69 , 70 , 71 ].…”

“…The heights of different age groups were determined according to existing studies [ 69 , 70 , 71 ]. The breath frequency, upper respiratory tract volume, and tidal volume of the population were based on existing studies [ 20 , 70 ]. Particles were assumed to be spherical with a density of 1.0 g·cm −3 [ 19 , 22 , 64 ].…”

“…When PM 2.5 enters the respiratory system, it will deposit in the head (above the pharynx), the trachea bronchus, and the pulmonary region [ 19 , 20 , 21 ]. The results of exposure experiments validate that the smaller the size of PM, the easier it is to deposit in the pulmonary region.…”

“…Only 30% of the gold nanoparticles are deposited in the tracheal epithelium, which may quickly excrete with the movement of cilia. PM deposited in the pulmonary region may stay for one to several days [ 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. The studies proved that the metal nanoparticles deposited in the pulmonary region were still partially undissolved after 24 h, and the water-soluble metal ions could be cleared faster in the pulmonary region.…”