Health effects of PM2.5 on children and health burden and associated economic burden of PM2.5 in Ho Chi Minh City, Vietnam

Ambient fine particulate matter (PM2.5) is a growing issue in Ho Chi Minh City (HCMC), the most populous province in Vietnam. Study on the adverse health effects, particularly on children, caused by exposure to PM2.5 has still been sparse in the city. This study aimed to evaluate the health effects of PM2.5 on children and estimate the burdens of PM2.5, including health and associated economic burdens, among the whole population in HCMC, Vietnam.The study collected the daily PM2.5 concentrations from the United State Consulate in HCMC and the Vietnam National University in HCMC (two fixed monitoring stations) from 2016 – 2019. The health database was collected from hospitals and commune health stations. First, the study collected computerized records of children hospitalized by acute lower respiratory infections – ALRI (61,204 records) and asthma (11,223 records) in all pediatric hospitals. The generalized linear models with the family of quasi-Poisson distribution were used to determine the association between daily exposure to PM2.5 and hospital admissions for respiratory diseases (ALRI, asthma). Second, the study collected data from 163,868 women with singleton pregnancies from three maternity hospitals in HCMC. Linear regression and logistic regression were employed to determine the association between exposure to PM2.5 and birth weight (BW), preterm birth (PTB), and term low birth weight (LBW). The adverse effects of PM2.5 were estimated during five different periods of PM2.5 exposure, including the first month of pregnancy, the first trimester, the second trimester, the third trimester, and the entire pregnancy.Third, 28,837 deaths recorded in 2019 were analyzed to calculate the death rate. The Environmental Benefits Mapping and Analysis Program - Community Edition (BenMAP-CE) was applied to estimate the health and economic benefits in three controlling scenarios of annual average PM2.5 concentration in 2019. The three scenarios were rolling back to the World Health Organization's annual average Air Quality Guideline values of 5 µg/m3 (guideline value in 2021) and 10 µg/m3 (guideline value in 2005 which becomes Interim Target 4 of 2021 WHO Air Quality Guideline), and the Vietnamese annual average standard of 25 µg/m3.The study found that the mean of daily average PM2.5 concentration in HCMC from 2016-2019 was 28.0 µg/m3, exceeding the Vietnamese standard and the WHO guidelines. Each 10 µg/m3 increase in PM2.5 posed an excess risk of 1.86% (95% CI: 0.24% ~ 3.52%) ALRI admission after six days of exposure (lag6). Exposure to PM2.5 resulted in more hospital admissions in male children and the age group from 2 to under 5 years old than in females and the age group one or under, respectively. Similarly, ambient PM2.5 is associated with hospital admissions for asthma among children under 5 years old. The excess risk of hospital admission was 3.86% (95% CI: 0.44%~7.4%) per 10 μg/m3 increase in PM2.5 level (4-day average exposure), females are sensitive than males and age group from 2-5 are more vulnerable than the age group 1 or under.The study also indicated that prenatal exposure to PM2.5 decreased BW and increased the risk of PTB. Each 10 µg/m3 increase in PM2.5 during the second trimester lowered with 11.8 g the BW (95% confident interval - CI: 5.2 – 18.3) and increased with 23.1% the risk of PTB (Odds ratio – OR = 1.23, 95%CI: 1.14 – 1.34). However, the association between maternal exposure to PM2.5 and the risk of term LBW was not statistically significant.Applying the BenMAP-CE, the pooled number of avoided deaths of all causes were 3,785 (1,179-6,335), 3,195 (982-5,468), and 1,300 (384-2,386) for three scenarios, respectively. The associated economic benefits were $ 0.8-6.2, $ 0.6-5.4, and $ 0.2-2.3 billion, respectively.Overall, the study findings show that the annual average concentration of PM2.5 in HCMC exceeded the Air Quality Guideline of the World Health Organization and significantly contributed to increasing respiratory diseases among children. Additionally, maternal exposure to PM2.5 shows a risk of a decrease in BW and the risk of PTB. Meanwhile, controlling PM2.5 greatly benefits health and the economy; thus, the city should have action plans for mitigating the PM2.5 pollution.