The Association between Air Pollution and Outpatient and Inpatient Visits in Shenzhen, China

Association between short-term exposure to ambient air pollutants and the risk of hospital visits for acute upper respiratory tract infections among adults: a time-series study in Ningbo, China

OBJECTIVES

Acute upper respiratory tract infections (AURTIs) are prevalent in the general population. However, studies on the association of short-term exposure to air pollution with the risk of hospital visits for AURTIs in adults are limited. This study aimed to explore the short-term exposure to air pollutants among Chinese adults living in Ningbo.

METHODS

Quasi-Poisson time serious regressions with distributed lag non-linear models (DLNM) were applied to explore the association between ambient air pollution and AURTIs cases. Patients ≥ 18 years who visit three hospitals, being representative for urban, urban-rural junction and rural were included in this retrospective study.

RESULTS

In total, 104,441 cases with AURTIs were enrolled in hospital during 2015-2019. The main results showed that particulate matter with an aerodynamic diameter less than 2.5 μm (PM2.5), nitrogen dioxide (NO2) and nitrogen dioxide (SO2), were positively associated to hospital visits for AURTIs, except for nitrogen dioxide (O3), which was not statistically significant. The largest single-lag effect for PM2.5 at lag 8 days (RR = 1.02, 95%CI: 1.08-1.40), for NO2 at lag 13 days (RR = 1.03, 95%CI: 1.00-1.06) and for SO2 at lag 5 days (RR = 1.27, 95%CI: 1.08-1.48), respectively. In the stratified analysis, females, and young adults (18-60 years) were more vulnerable to PM2.5 and SO2 and the effect was greater in rural areas and urban-rural junction.

CONCLUSIONS

Exposure to ambient air pollution was significantly associated with hospital visits for AURTIs. This study provides epidemiological evidence for policymakers to control better air quality and establish an enhanced system of air pollution alerts.

An association between PM2.5 and pediatric respiratory outpatient visits in four Chinese cities

BACKGROUND

The effects of exposure to particulate matter with aerodynamic diameter less than 2.5 μm (PM_2.5) on children's respiratory system were investigated in numerous epidemiological literatures. However, studies on the association between PM_2.5 and pediatric outpatient visits for respiratory diseases, especially considering the multicenter studies were limited in China.

OBJECTIVES

To study the association between the short-term exposure to PM_2.5 and the number of children's outpatient visits for respiratory diseases in four Chinese cities as well as the pooled health effects.

METHODS

Data of pediatric outpatient visits for respiratory diseases (RD, ICD: J00-J99) from representative hospitals in Shijiazhuang (SJZ), Xi'an (XA), Nanjing (NJ) and Guangzhou (GZ) in China from 2015 to 2018 were collected and the air quality data for the same period were collected from environmental protection departments. Generalized additive model (GAM) with quasi-Poisson regression was conducted to analyze the effects of PM_2.5 on the number of pediatric outpatient visits in each city. Single-day lag model (lag0 to lag7) and moving average lag model (lag01 and lag07) were used to examine the lag effects and cumulative effects. Random-effects meta-analysis was used to pool the estimated risks of four cities. The interactions between PM_2.5 and temperature were also explored.

RESULTS

The average daily/total outpatient visits for RD, in SJZ, XA, NJ and GZ from 2015 to 2018 were 854.2/1,245,384, 2353.9/3,439,025, 1267.2/1,851,438 and 1399.5/2,044,740 respectively. The percentages of acute upper respiratory infections (URD, ICD: J00-J06) and other acute lower respiratory infections (LRD, ICD: J20-J22) in RD were 33%, 13% (SJZ), 43%, 32% (XA), 26%, 21% (NJ) and 54%, 26% (GZ). The largest pooled estimates of single-day lag effects for RD, URD, and LRD were at lag0, lag0 and lag1. Every 10 μg/m³ increase in PM_2.5 concentration was associated with a 0.46% (95%CI: 0.21%-0.70%), 0.50% (95%CI: 0.19%-0.81%) and 0.42% (95%CI: 0.06%-0.79%) increased number of outpatient visits significantly. While max cumulative effects which were all at lag 07 were 1.10% (95%CI: 0.46%-1.74%), 0.96% (95%CI: 0.20%-1.73%) and 1.06% (95%CI: 0.12%-2.00%). Less polluted cities (GZ and NJ) showed greater city-specific excess risks, but the excess risks significantly decreased after adjusting for NO₂ in two-pollutant models. Generally, PM_2.5 showed larger health hazards on lower temperature days.

CONCLUSIONS

Our study showed that exposure to the ambient PM_2.5 was associated with the increase of the number of outpatient visits with pediatric respiratory diseases in four Chinese cities. The health effects of PM_2.5 may not be independent of other air pollutants and could be modified by temperature.

Ambient air pollution and risk of respiratory infection among adults: evidence from the multiethnic study of atherosclerosis (MESA)

BACKGROUND

Air pollution may affect the risk of respiratory infection, though research has focused on uncommon infections or infections in children. Whether ambient air pollutants increase the risk of common acute respiratory infections among adults is uncertain, yet this may help understand whether pollutants influence spread of pandemic respiratory infections like COVID-19.

OBJECTIVE

To estimate the association between ambient air pollutant exposures and respiratory infections in adults.

METHODS

During five study examinations over 12 years, 6536 participants in the multiethnic study of atherosclerosis (MESA) reported upper respiratory tract infections, bronchitis, pneumonia or febrile illness in the preceding 2 weeks. Using a validated spatiotemporal model, we estimated residential concentrations of ambient PM2.5, NOx and NO2 for the 2-6 weeks (short-term) and year (long-term) prior to each examination.

RESULTS

In this population aged 44-84 years at baseline, 10%-32% of participants reported a recent respiratory infection, depending on month of examination and study region. PM2.5, NOx and NO2 concentrations over the prior 2-6 weeks were associated with increased reporting of recent respiratory infection, with risk ratios (95% CIs) of 1.04 (1.00 to 1.09), 1.15 (1.10 to 1.20) and 1.21 (1.10 to 1.33), respectively, per increase from 25th to 75th percentile in residential pollutant concentration.

CONCLUSION

Higher short-term exposure to PM2.5 and traffic-related pollutants are associated with increased risk of symptomatic acute respiratory infections among adults. These findings may provide an insight into the epidemiology of COVID-19.

Associations of short-term exposure to air pollution and emergency department visits for pediatric asthma in Shanghai, China

There is limited evidence regarding the relationship between air pollution and pediatric asthma in developing countries. This study aimed to investigate the association between short-term exposure to ambient air pollutants and pediatric asthma emergency department (ED) visits in Shanghai, China. We collected data on six criteria air pollutants (PM_2.5, PM₁₀, NO₂, SO₂, CO, and O₃) and daily ED visits for pediatric asthma patients from 66 hospitals in Shanghai from 2016 to 2018. The generalized additive model combined with polynomial distributed lag model was applied to explore the associations. We fitted two-pollutant models and stratified the analyses by sex, age, and season. In total, we identified 108,817 emergency department visits for pediatric asthma. A 10 μg/m³ increase in the concentrations of PM_2.5, NO₂, SO₂, and O₃ was significantly associated with increased risks of pediatric asthma ED visits, with relative risk of pediatric asthma of 1.011 [95% confidence interval (CI): 1.002, 1.021], 1.030 (95%CI: 1.017, 1.043), 1.106 (95%CI: 1.041, 1.174), and 1.009 (95%CI: 1.001, 1.017), respectively. The associations of NO₂ remained robust in the two-pollutant models. There were stronger associations for older children (6-18 years) and in warm seasons. The concentration-response curves for pediatric asthma and PM_2.5, NO₂, SO₂, and O₃ were steeper at lower and moderate concentrations but became flatter at higher concentrations. This analysis provided evidence that short-term exposure to air pollutants (PM_2.5, NO₂, SO₂, and O₃) could increase the risk of asthma exacerbations among children, and health benefits would be gained from improved air quality.

Impacts of AOD Correction and Spatial Scale on the Correlation between High-Resolution AOD from Gaofen-1 Satellite and In Situ PM2.5 Measurements in Shenzhen City, China

Satellite-derived aerosol optical depth (AOD) is widely used to estimate surface PM2.5 concentrations. Most AOD products have relatively low spatial resolutions (i.e., ≥1 km). Consequently, insufficient research exists on the relationship between high-resolution (i.e., <1 km) AOD and PM2.5 concentrations. Taking Shenzhen City, China as the study area, we derived AOD at the 16-m spatial resolution for the period 2015–2017 based on Gaofen-1 (GF-1) satellite images and the Dark Target (DT) algorithm. Then, we extracted AOD at spatial scales ranging from 40 m to 5000 m and applied vertical and humidity corrections. We analyzed the correlation between AOD and PM2.5 concentrations, and the impacts of AOD correction and spatial scale on the correlation. It was found that the DT-derived GF-1 AOD at different spatial scales had statistically significant correlations with surface PM2.5 concentrations, and the AOD corrections strengthened the correlations. The correlation coefficients (R) between AOD at different spatial scales and PM2.5 concentrations were 0.234–0.329 and 0.340–0.423 before and after AOD corrections, respectively. In spring, summer, autumn, and winter, PM2.5 concentrations had the best correlations with humidity-corrected AOD, uncorrected AOD, vertical and humidity-corrected AOD, and uncorrected AOD, respectively, indicating a distinct seasonal variation of the aerosol characteristics. At spatial scales of 1–5 km, AOD at finer spatial scales generally had higher correlations with PM2.5 concentrations. However, at spatial scales <1 km, the correlations fluctuated irregularly, which could be attributed to scale mismatches between AOD and PM2.5 measurements. Thus, 1 km appears to be the optimum spatial scale for DT-derived AOD to maximize the correlation with PM2.5 concentrations. It is also recommended to aggregate very high-resolution DT-derived AOD to an appropriate medium resolution (e.g., 1 km) before matching them with in situ PM2.5 measurements in regional air pollution studies.

Characteristics and Trends of Ambient Ozone and Nitrogen Oxides at Urban, Suburban, and Rural Sites from 2011 to 2017 in Shenzhen, China

The emissions of nitrogen oxides (NOx) decreased under China’s air quality control policies. However, concern remains regarding the response of ozone (O3) in the metropolitan areas. The characteristics and trends of ambient O3 and NOx in Shenzhen were investigated during the 2011–2017 period. Both the human population and vegetation are exposed to higher O3 at suburban and rural sites than at the urban site. The O3 weekend effect is significant (p = 0.062) at the urban site, with O3 levels 1.19 ppb higher on Sunday than on weekdays. Solar radiation, precipitation, and relative humidity are the most relevant meteorological factors that affect O3 daily variations. Wind speed is the least relevant factor, but wind direction is related to the presence of high O3 air concentrations. Both 1-h and 8-h O3 exhibit an increase, opposite to the trend of NOx. A slight decline in O3 occurs in autumn at less urbanized sites. The increase in O3 is more prevalent and rapid in the winter at more urbanized sites. This can be due to the transport of increased O3 from northern China, as well as a lowered O3 titration effect with NOx reduction. O3 increases fastest at the urban site, with an estimated rate of 4.3% (95% confidence intervals (CIs): 0.96, 8.25) per year (p < 0.05) for 8-h O3 and 2.5% (95% CIs: −0.46, 6.12) per year (p > 0.1) for 1-h O3, posing greater human health risks to areas with high population density.

The Effect of PM2.5 from Household Combustion on Life Expectancy in Sub-Saharan Africa

Household fuel combustion, especially using solid combustibles (biomass and fossil fuels), for cooking and other activities produces emissions that contribute to concentrations of indoor as well as outdoor air pollutants such as particulate matter with diameter smaller than 2.5 μm (PM_2.5) that deteriorate health and likely affect life expectancy (LEX). This study investigates the impact of PM_2.5 from household combustion on LEX considering several covariates while controlling for ambient PM_2.5 generated by other sectors. The generalized method of moments (GMM) model and the panel cointegration model were applied to a dataset of 43 Sub-Saharan Africa (SSA) countries over the time period of 1995–2010. Both approaches provide similar results indicating that household PM_2.5 is significantly and negatively associated with higher aggregate LEX in the long-run, and, to a greater degree for female’s. Also, among the control variables, PM_2.5 from the transport sector has a greater influence on male’s LEX. Thus, efforts should be combined to reduce household PM_2.5 since lower levels are associated with increased LEX.