Particulate air pollution in Ho Chi Minh city and risk of hospital admission for acute lower respiratory infection (ALRI) among young children

How air pollution fuels respiratory infections in children: current insights

Background

Air pollution is a significant global health concern, particularly for younger children who are especially susceptible to its adverse effects. Pollutants such as particulate matter (PM), nitrogen oxides (NO and NO₂), sulfur dioxide (SO2), ozone (O3), and carbon monoxide (CO) are associated with increased risks of upper respiratory tract infections (URTI) and lower respiratory tract infections (LRTI). While this association is well-documented, there are critical gaps in understanding the magnitude of these risks, the roles of specific pollutants, and the influence of age, sex, and exposure duration.

Methods

To confirm the relationship between air pollution and respiratory tract infections in children and to identify areas for further research on reducing pollution-related respiratory damage, a literature review was conducted using the MEDLINE/PubMed database for studies published from January 2000 to December 2024. Eligible studies included randomized controlled trials, cohort studies, and meta-analyses focusing on the relationship between air pollution and respiratory infections in children. Studies were grouped by pollutant type, exposure timing, and infection type.

Results

The literature analysis confirmed that pollution significantly increases the risk of URTI and LRTI in children, with infants and young children being the most vulnerable. Potential mechanisms for the development of respiratory tract pollution-related diseases include the promotion of oxidative stress, induction of inflammatory responses, deregulation of the immune system, and genetic alterations. Prenatal exposure significantly alters respiratory tract development, increasing the risk of LRTI and acute otitis media (AOM) early in life. Both short-term and long-term postnatal exposures can cause severe and recurrent LRTIs, reducing quality of life and leading to frequent hospitalizations and early death. However, the available data do not allow for precise definition of the magnitude of the risk, the individual and combined roles of specific pollutants, and the influence of factors such as age, sex, duration, and site of exposure on the development and severity of respiratory infections. Inconsistent findings on pollutant combinations and specific diseases like otitis media highlight the need for further research.

Conclusion

Air pollution is a major risk factor for respiratory infections in children, both prenatal and postnatal exposure can have significant negative impact. However, present knowledge is inadequate to develop effective preventive and therapeutic measures. Further studies are needed to minimize these cultural limits. In particular, it is necessary to delve deeper into how the various pollutants circulate, how they interact with each other, and how they are influenced by climate change and other environmental drivers. Results of these key researches can be translate into clinical and public health practice capable to help protect and improve children's environmental health.

The mediating effect of air pollution on the association between meteorological factors and influenza-like illness in China

PURPOSE

Although numerous studies have explored the complex relationship between air pollution, meteorological factors and respiratory infections, evidence for a mediating effect of air pollutants being involved in the association between meteorological factors and Influenza-like illness (ILI) is limited.

METHODS

Correlations among ILI cases, air pollutants and meteorological factors were examined with Pearson correlation analyses. Further, we formulated six candidate mediation models to explore the mediating effect of air pollutant on the association between meteorological factors and ILI infections.

RESULTS

The meteorological factors minimum temperature/maximum humidity moderated by maximum humidity/minimum temperature and pressure directly affect ILI infections, and that some of meteorological factors can also indirectly affect them through air pollutants. Increases in maximum humidity and minimum temperature can directly reduce the numbers of ILI cases, or indirectly reduce them by reducing the concentration of air pollutants.

CONCLUSION

When the haze with low temperature, low humidity is forecasted by the meteorological agency, the environmental protection departments can take effective control measures to reduce the concentration of air pollutants, and public health departments should advocate human behavioral changes in order to mitigate and control ILI prevalence.

The burden of acute respiratory infection attributable to fine particulate matter brought by dust storms among children under 5 years of age in low- and middle-income countries

BACKGROUND

Long-term exposure to fine particulate matter brought by dust storms (dust PM2.5) poses a significant risk to children's health, particularly those in low- and middle-income countries (LMICs). To quantify the impact of dust PM2.5 on children, current research focuses on acute respiratory infection (ARI) as a key health outcome, given its significant contribution to child mortality. However, the relationship used to evaluate the disease burden is mainly based on the total PM2.5 concentration, neglecting the specific effect of dust PM2.5 distinct from other PM2.5.This study aimed to develop a dust-specific exposure-response function (ERF) of ARI in children <5 years of age (U5-ARI) for future risk assessments.

METHOD

We combined population data derived from the Demographic and Health Survey covering 53 LMICs, with environmental data, including the gridded concentration of dust PM2.5. ARI in children <5 years of age (U5-ARI) was the outcome of interest, which was defined by a standard questionnaire-based method. The dust PM2.5 exposure was derived from the integration of two well-recognized datasets, and matched to each participant at the community level. We analyzed the linear association between the annual average dust PM2.5 concentration and the odds of U5-ARI with logistic regression and fixed effects after adjusting for multiple covariates. We also used the spline method to develop a dust-specific ERF. Based on the function, we estimated the burden of dust-associated U5-ARI across 100 LMICs and compared it with the results from two well-established functions of total PM2.5 mass.

RESULTS

The analysis of 1,223,118 children showed that a 10 μg/m3 increase in dust PM2.5 was associated with a 7.43% (95% confidence interval [CI]: 4.77-10.15%) increase in the odds of U5-ARI. The spline model indicated that the risk of U5-ARI increased monotonically and linearly with dust PM2.5 concentration with no evident effect threshold. In 2017, based on the dust-specific ERF, across the 100 LMICs, the number of dust-associated U5-ARI was estimated to be 159,000 (95% CI: 153,000-165,000), which was consistently higher than the estimates from ERFs based on total PM2.5 mass (142,000 [95% CI: 97,000-181,000] or 114,000 [95% CI: 80,000-153,000]). The long-term dust PM2.5 exposure contributed to 12-13% of all the children affected by U5-ARI between 2000 and 2017. The geographic hotspots were the arid and populous areas of South Asia and Africa.

CONCLUSION

This study provides critical insight into the association between long-term exposure to dust PM2.5 and the health of children in LMICs, highlighting the need for specific ERFs to distinguish the adverse effects of different PM2.5 components. Personal protection during sand dust storms can be an effective intervention to safeguard the respiratory health of children.

Long-term air pollution exposure and the risk of primary graft dysfunction after lung transplantation

BACKGROUND

Primary graft dysfunction (PGD) contributes substantially to both short- and long-term mortality after lung transplantation, but the mechanisms that lead to PGD are not well understood. Exposure to ambient air pollutants is associated with adverse events during waitlisting for lung transplantation and chronic lung allograft dysfunction, but its association with PGD has not been studied. We hypothesized that long-term exposure of the lung donor and recipient to high levels of ambient air pollutants would increase the risk of PGD in lung transplant recipients.

METHODS

Using data from 1428 lung transplant recipients and their donors enrolled in the Lung Transplant Outcomes Group observational cohort study, we evaluated the association between the development of PGD and zip-code-based estimates of long-term exposure to 6 major air pollutants (ozone, nitrogen dioxide, sulfur dioxide, carbon monoxide, particulate matter 2.5, and particulate matter 10) in both the lung donor and the lung recipient. Exposure estimates used daily EPA air pollutant monitoring data and were based on the geographic centroid of each subject's residential zip code. Associations were tested in both univariable and multivariable models controlling for known PGD risk factors.

RESULTS

We did not find strong associations between air pollutant exposures in either the donor or the recipient and PGD.

CONCLUSIONS

Exposure to ambient air pollutants, at the levels observed in this study, may not be sufficiently harmful to prime the donor lung or the recipient to develop PGD, particularly when considering the robust associations with other established PGD risk factors.

Impacts of short-term exposure to ambient air pollutants on outpatient visits for respiratory diseases in children: a time series study in Yichang, China

BACKGROUND

There is growing evidence that the occurrence and severity of respiratory diseases in children are related to the concentration of air pollutants. Nonetheless, evidence regarding the association between short-term exposure to air pollution and outpatient visits for respiratory diseases in children remains limited. Outpatients cover a wide range of disease severity, including both severe and mild cases, some of which may need to be transferred to inpatient treatment. This study aimed to quantitatively evaluate the impact of short-term ambient air pollution exposure on outpatient visits for respiratory conditions in children.

METHODS

This study employed data of the Second People's Hospital of Yichang from January 1, 2016 to December 31, 2023, to conduct a time series analysis. The DLNM approach was integrated with a generalized additive model to examine the daily outpatient visits of pediatric patients with respiratory illnesses in hospital, alongside air pollution data obtained from monitoring stations. Adjustments were made for long-term trends, meteorological variables, and other influencing factors.

RESULTS

A nonlinear association was identified between PM2.5, PM10, O3, NO2, SO2, CO levels and the daily outpatient visits for respiratory diseases among children. All six pollutants exhibit a hysteresis impact, with varying durations ranging from 4 to 6 days. The risks associated with air pollutants differ across various categories of children's respiratory diseases; notably, O3 and CO do not show statistical significance concerning the risk of chronic respiratory conditions. Furthermore, the results of infectious respiratory diseases were similar with those of respiratory diseases.

CONCLUSIONS

Our results indicated that short-term exposure to air pollutants may contribute to an increased incidence of outpatient visits for respiratory illnesses among children, and controlling air pollution is important to protect children's health.

Estimating the burden of diseases attributed to PM2.5 using the AirQ + software in Mashhad during 2016-2021

The study used the AirQ + software developed by the World Health Organization (WHO) to evaluate the health impacts associated with long-term exposure to PM2.5 in Mashhad, Iran. For this purpose, we analyzed the daily average concentrations of PM2.5 (with a diameter of 2.5 micrometers or less) registered by the air quality monitoring stations from 2016 to 2021. The levels of PM2.5 surpassed the Air Quality Guidelines (AQG) limit value of 5 µg/m3 (annual value) established by WHO. The findings revealed that the burden of mortality (from all-natural causes) at people above 30 years old associated with PM2.5 exposures was 2093 [95% confidence interval [CI]: 1627-2314] deaths in 2016 and 2750 [95% CI: 2139-3038] deaths in 2021. In general, the attributable mortality from specific causes of deaths (e.g., COPD (chronic obstructive pulmonary diseases), IHD (ischemic heart diseases) and stroke) in people above 25 years old increased between the years, but the mortality from lung cancer was stable at 46 [95% CI: 33-59] deaths in 2016 and 48 [95% CI: 34-61] deaths in 2021. The attributable mortality from ALRI (Acute Lower Respiratory Infection) in children below 5 years old increased between the years. We also found differences in mortality cases from IHD and stroke among the age groups and between the years 2016 and 2021. It was concluded that burden of disease methodologies are suitable tools for regional and national policymakers, who must take decisions to prevent and to control air pollution and to analyze the cost-effectiveness of interventions.

Research on the cascading mechanism of "urban built environment-air pollution-respiratory diseases": a case of Wuhan city

Background

Most existing studies have only investigated the direct effects of the built environment on respiratory diseases. However, there is mounting evidence that the built environment of cities has an indirect influence on public health via influencing air pollution. Exploring the "urban built environment-air pollution-respiratory diseases" cascade mechanism is important for creating a healthy respiratory environment, which is the aim of this study.

Methods

The study gathered clinical data from 2015 to 2017 on patients with respiratory diseases from Tongji Hospital in Wuhan. Additionally, daily air pollution levels (sulfur dioxide (SO2), nitrogen dioxide (NO2), particulate matter (PM2.5, PM10), and ozone (O3)), meteorological data (average temperature and relative humidity), and data on urban built environment were gathered. We used Spearman correlation to investigate the connection between air pollution and meteorological variables; distributed lag non-linear model (DLNM) was used to investigate the short-term relationships between respiratory diseases, air pollutants, and meteorological factors; the impacts of spatial heterogeneity in the built environment on air pollution were examined using the multiscale geographically weighted regression model (MGWR).

Results

During the study period, the mean level of respiratory diseases (average age 54) was 15.97 persons per day, of which 9.519 for males (average age 57) and 6.451 for females (average age 48); the 24 h mean levels of PM10, PM2.5, NO2, SO2 and O3 were 78.056 μg/m3, 71.962 μg/m3, 54.468 μg/m3, 12.898 μg/m3, and 46.904 μg/m3, respectively; highest association was investigated between PM10 and SO2 (r = 0.762, p < 0.01), followed by NO2 and PM2.5 (r = 0.73, p < 0.01), and PM10 and PM2.5 (r = 0.704, p < 0.01). We observed a significant lag effect of NO2 on respiratory diseases, for lag 0 day and lag 1 day, a 10 μg/m3 increase in NO2 concentration corresponded to 1.009% (95% CI: 1.001, 1.017%) and 1.005% (95% CI: 1.001, 1.011%) increase of respiratory diseases. The spatial distribution of NO2 was significantly influenced by high-density urban development (population density, building density, number of shopping service facilities, and construction land, the bandwidth of these four factors are 43), while green space and parks can effectively reduce air pollution (R2 = 0.649).

Conclusion

Previous studies have focused on the effects of air pollution on respiratory diseases and the effects of built environment on air pollution, while this study combines these three aspects and explores the relationship between them. Furthermore, the theory of the "built environment-air pollution-respiratory diseases" cascading mechanism is practically investigated and broken down into specific experimental steps, which has not been found in previous studies. Additionally, we observed a lag effect of NO2 on respiratory diseases and spatial heterogeneity of built environment in the distribution of NO2.

Benefits of Short-term Premature Mortality Reduction Attributed to PM2.5 Pollution: A Case Study in Long an Province, Vietnam

PM2.5 pollution exposure is the leading cause of disease burden globally, especially in low- and middle-income countries, including Vietnam. Therefore, economic damage in this context must be quantified. Long An province in the Southern Key Economic (SKE) region was selected as a research area. This study aimed to evaluate PM2.5-related human health effects causing early deaths attributable to respiratory, cardiovascular, and circulatory diseases in all ages and genders. Health end-points and health impact estimation, economic loss model, groups of PM2.5 concentration data, data of exposed population, data of baseline premature mortality rate, and data of health impact functions were used. Hourly PM2.5 concentration data sets were generated specifically using the coupled Weather Research and Forecasting Model (WRF)/Community Multiscale Air Quality Modelling System (CMAQ) models. Daily PM2.5 pollution levels considered mainly in the dry season (from January to April 2018) resulted in 12.9 (95% CI - 0.6; 18.7) all-cause premature deaths per 100,000 population, of which 7.8 (95% CI 1.1; 7.1), 1.5 (95% CI - 0.2; 3.1), and 3.6 (95% CI - 1.5; 8.5) were due to respiratory diseases (RDs; 60.54%), cardiovascular diseases (CVDs; 11.81%), and circulatory system diseases (CSDs; 27.65%) per 100,000 population, respectively. The total economic losses due to acute PM2.5 exposure-related premature mortality cases reached 62.0 (95% CI - 2.7; 89.6) billion VND, equivalent to 8.3 (95% CI - 0.4; 12.0) million USD. The study outcomes contributed remarkably to the generation and development of data sources for effectively managing ambient air quality in Long An.

Short-term effects of air pollution on hospitalization for acute lower respiratory infections in children: a time-series analysis study from Lanzhou, China

BACKGROUND

Short-term exposure to air pollution is associated with acute lower respiratory infections (ALRI) in children. We investigated the relationship between hospitalization for ALRI in children and air pollutant concentrations from January 1, 2014 to December 31, 2020 in Lanzhou City.

METHODS

We collected data on air pollutant concentrations and children's hospitalization data during the study period. A time series regression analysis was used to assess the short-term effects of air pollutants on ALRI in children, and subgroup analyses and sensitivity analyses were performed.

RESULTS

A total of 51,206 children with ALRI were studied, including 40,126 cases of pneumonia and 11,080 cases of bronchiolitis. The results of the study revealed that PM2.5, PM10, SO2 and NO2 were significantly associated with hospitalization for ALRI in children aged 0-14 years. For each 10 µg/m3 increase in air pollutant concentration in lag0-7, the relative risk of ALRI hospitalization in children due to PM2.5, PM10, SO2 and NO2 increased by 1.089 (95%CI:1.075, 1.103), 1.018 (95%CI:1.014, 1.021), 1.186 (95%CI:1.154. 1.219) and 1.149 (95%CI:1.130, 1.168), respectively.

CONCLUSIONS

PM2.5, PM10, SO2 and NO2 short-term exposures were positively associated with ALRI, pneumonia and bronchiolitis hospitalizations in Lanzhou, China. Local governments should make efforts to improve urban ambient air quality conditions to reduce hospitalization rates for childhood respiratory diseases.

Indirect Methods to Determine the Risk of Damage to the Health of Firefighters and Children Due to Exposure to Smoke Emission from Burning Wood/Coal in a Controlled Environment

People are constantly exposed to particulate matter and chemicals released during fires. However, there are still few studies on gas and particulate emissions related to exposure to burning firewood and charcoal during forest fires, making it difficult to understand the effects on the health of the population. The objective of this study was to quantify the metal(loid)s present in the smoke from wood and charcoal fires through the deposition of metals in beef topside and pork loin, considering the routes of skin exposure, inhalation, and ingestion, contributing to the understanding of metals in the increase of the risks of cancer and mortality associated with firefighting and children. The concentrations of metals [aluminum (Al), chromium (Cr), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), molybdenum (Mo), vanadium (V), zinc (Zn)] and metalloids arsenic (As) were determined by inductively coupled plasma-mass spectrometry (ICP OES) after microwave digestion. Moreover, we assessed the associated risk regarding the elemental intake of these elements through the smoke, using the hazard quotient (HQ), hazard index (HI), Total Hazard Index (HIt), and carcinogenic risk (CR). All samples had results for HQ and HIt < 1, indicating a non-potential health risk. However, the carcinogenic risks posed by As and Cr via the three exposure pathways (except for inhalation exposure to children and adults, and by Cr via ingestion and inhalation for children and adults) exceeded the standard threshold. In conclusion, continuous exposure of firefighters or children to smoke from fires containing high concentrations of heavy metals such as As and Cr can be harmful to health. The study used animal tissues; thus, new methods must be developed to quantify the concentration of heavy metals deposited in human tissue when humans are exposed to smoke from fires.

Associations between air pollutant and pneumonia and asthma requiring hospitalization among children aged under 5 years in Ningbo, 2015-2017

Introduction

Exposure to ambient air pollutants is associated with an increased incidence of respiratory diseases such as pneumonia and asthma, especially in younger children. We investigated the relationship between rates of hospitalization of children aged under 5 years for pneumonia and asthma and the concentration of air pollutants in Ningbo between January 1, 2015 and August 29, 2017.

Methods

Data were obtained from the Ningbo Air Quality Data Real-time Publishing System and the big data platform of the Ningbo Health Information Center. A generalized additive model was established via logarithmic link function and utilized to evaluate the effect of pollutant concentration on lag dimension and perform sensitivity analysis.

Results

A total of 10,301 cases of pneumonia and 115 cases of asthma were identified over the course of this study. Results revealed that PM2.5, PM10, SO2 and NO2 were significantly associated with hospitalization for pneumonia and asthma in children under 5 years of age. For every 10-unit increase in lag03 air pollutant concentration, hospitalization for pneumonia and asthma due to PM2.5, PM10, SO2 and NO2 increased by 2.22% (95%CI: 0.64%, 3.82%), 1.94% (95%CI: 0.85%, 3.04%), 11.21% (95%CI: 4.70%, 18.10%) and 5.42% (95%CI: 3.07%, 7.82%), respectively.

Discussion

Adverse effects of air pollutants were found to be more severe in children aged 1 to 5 years and adverse effects due to PM2.5, PM10 and SO2 were found to be more severe in girls. Our findings underscore the need for implementation of effective public health measures to urgently improve air quality and reduce pediatric hospitalizations due to respiratory illness.

Air pollution and pediatric respiratory hospital admissions in Bursa, Turkey: A time series study

We aimed to investigate the relation between air pollution and the number of daily hospitalizations due to pneumonia, asthma, bronchitis in children aged 0-18 in Bursa city of Turkey, between the years 2013-2018. The daily values of air pollutants (PM10, SO2, NO2, NOx, CO, and O3) from 2013 until 2018, were obtained. Adjusted Quasi-Poisson regression models including distributed lags, controlled for climate variables were used for data analysis. Increases in SO2, ozone, PMs, and nitrogen oxides were associated with pneumonia hospitalizations, increases in SO2 NOx and PMs were associated with asthma hospitalizations, and increases in SO2 and ozone were associated with bronchitis hospitalizations. Male hospitalization was related with SO2, ozone, and NOx; while female hospitalization was only related with SO2. This study showed that short-term exposure to air pollution is associated with an increased risk of pneumonia, asthma, and bronchitis hospitalization among children in Bursa.

Mortality benefits of reduction fine particulate matter in Vietnam, 2019

Introduction and objectives

Studies assessing the health benefits of air pollution reduction in Vietnam are scarce. This study quantified the annual mortality burden due to PM_2.5 pollution in Vietnam above the World Health Organization recommendation for community health (AQG: 5 μg/m³) and the proposed National Technical Regulation on Ambient Air Quality (proposed QCVN: 15 μg/m³).

Methodology

This study applied a health impact assessment methodology with the hazard risk function for non-communicable diseases (NCDs) and lower respiratory infections (LRIs) in the Global Exposure Mortality Model (GEMM) to calculate attributable deaths, Years of Life lost, and Loss of Life expectancy at birth due to air pollution in the Vietnamese population above 25 years of age in 11 provinces. We obtained annual average PM_2.5 concentrations for Vietnam in 2019 at a 3x3 km grid modeled using Mixed Linear regression and multi-data sources. Population and baseline mortality data were obtained from administrative data system in Vietnam. We reported the findings at both the provincial and smaller district levels.

Results

Annual PM_2.5 concentrations in all studied provinces exceeded both the AQG and the proposed QCVN. The maximum annual number of attributable deaths in the studied provinces if they had complied with WHO air quality guidelines was in Ha Noi City, with 5,090 (95%CI: 4,253-5,888) attributable deaths. At the district level, the highest annual rate of attributable deaths if the WHO recommendation for community health had been met was 104.6 (95%CI: 87.0-121.5) attributable deaths per 100,000 population in Ly Nhan (Ha Nam province).

Conclusion

A much larger number of premature deaths in Vietnam could potentially be avoided by lowering the recommended air quality standard. These results highlight the need for effective clean air action plans by local authorities to reduce air pollution and improve community health.

Associations between air pollutants and risk of respiratory infection: patient-based bacterial culture in sputum

Air pollution is a crucial risk factor for respiratory infection. However, the relationships between air pollution and respiratory infection based on pathogen detection are scarcely explored in the available literature. We detected respiratory infections through patient-based bacterial culture in sputum, obtained hourly data of all six pollutants (PM_2.5, PM₁₀, SO₂, NO, CO, and O₃) from four air quality monitoring stations, and assessed the relationships of air pollutants and respiratory bacterial infection and multi-drug-resistant bacteria. Air pollution remains a challenge for Mianyang, China, especially PM_2.5 and PM₁₀, and there are seasonal differences; pollution is the heaviest in winter and the lowest in summer. A total of 4237 pathogenic bacteria were detected, and the positive rate of multi-drug-resistant bacteria was 0.38%. Similar seasonal differences were found with respect to respiratory infection. In a single-pollutant model, all pollutants were significantly associated with respiratory bacterial infection, but only O₃ was significantly associated with multi-drug-resistant bacteria. In multi-pollutant models (adjusted for one pollutant), the relationships of air pollutants with respiratory bacterial infection remained significant, while PM_2.5, PM₁₀, and O₃ were significantly associated with the risk of infection with multi-drug-resistant bacteria. When adjusted for other five pollutants, only O₃ was significantly associated with respiratory bacterial infection and the risk of infection with multi-drug-resistant bacteria, showing that O₃ is an independent risk factor for respiratory bacterial infection and infection with multi-drug-resistant bacteria. In summary, this study highlights the adverse effects of air pollution on respiratory infection and the risk of infection with multi-drug-resistant bacteria, which may provide a basis for the formulation of environmental policy to prevent respiratory infections.

Association of short-term exposure to air pollution with emergency visits for respiratory diseases in children

Ambient air pollutants are health hazards to children. This study comprised 773,504 emergency department visits (EDVs) at 0–14 years of age with respiratory diseases in southern China. All air pollutants were positively associated with EDVs of total respiratory diseases, especially pneumonia. NO₂, PM₁₀, and PM_2.5 had intraday effects and cumulative effects on asthma EDVs. The effect of SO₂, PM₁₀, and PM_2.5 on pneumonia EDVs was stronger in girls than in boys. The effect of NO₂ on acute upper respiratory tract infection EDVs was greater in children aged 0–5 years old; however, the effect of PM₁₀ on acute upper respiratory tract infection EDVs was greater in the 6–14 years group. In a two-pollutant model, NO₂ was associated with bronchitis and pneumonia, and PM₁₀ was associated with acute upper respiratory tract infection. In this time-series study, NO₂ and PM₁₀ were risk indicators for respiratory diseases in children.

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Air pollution associates with children emergency visits for respiratory diseases

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NO₂ and PM₁₀ are risk indicators for respiratory diseases in children

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Young children are more sensitive to gaseous pollutants

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School-age children are more sensitive to PM₁₀

Children's exposure to air pollution in a natural gas industrial area and their risk of hospital admission for respiratory diseases

The rapid expansion of the natural gas industry to meet the global demand have raised environmental health concerns. Few studies have found that areas with natural gas industrial activity have poor air quality. However, the negative health impacts of ambient air pollution in a natural gas industrial area remain unclear. This study aimed to explore the relationship between short-term exposure to air pollution and hospital admissions for respiratory diseases among children in a natural gas industrial area in Bintulu, Malaysia. Daily hospital admissions for respiratory diseases among children were collected from a hospital in Bintulu from 2010 to 2019. Data on six air pollutants (PM₁₀, PM_2.5, SO₂, NO₂, O₃, and CO) in the study area were obtained from the Department of Environment Malaysia. Quasi-Poisson time series regressions with distributed lag non-linear models (DLNM) were applied to explore the associations between ambient air pollution and childhood hospitalisations for respiratory diseases. Stratification analyses were performed by gender and age group to identify the vulnerable populations. A 10 μg/m³ increased PM_2.5 and SO₂ was associated with hospital admissions for respiratory diseases among children with the greatest relative risk of RR 1.089 (95% CI 1.001-1.183) at cumulative lag 0-2 days and RR 1.229 (95% CI 1.073-1.409) at cumulative lag 0-6 days, respectively. There was no significant association between short-term exposure of PM₁₀, NO₂, CO, and O₃ with childhood respiratory hospitalisation. The association between PM_2.5 and SO₂ exposure and hospital admissions for childhood respiratory diseases in the two pollutants model remained statistically significant. There were stronger associations in younger children aged 0-4 years and girls. This study reveals that short-term exposure to SO₂ was associated with a higher risk of respiratory hospitalisations among children in Bintulu than PM_2.5. Better air quality control is necessary for children's health living in the natural gas industrial area.

Three Exposure Metrics for Fine Particulate Matter Associated With Outpatient Visits for Acute Lower Respiratory Infection Among Children in Guangzhou, China

Ambient fine particulate matter (PM_2.5) is associated with an elevated risk of acute lower respiratory infections (ALRI). However, this association has not been examined using alternative exposure metrics. We collected outpatient data of patients with ALRI aged <14 years from the administrative database of a large tertiary hospital in Guangzhou, China, from 2013 to 2019. Ambient PM_2.5 was measured using three metrics: (a) daily mean, (b) daily excessive concentration hours (DECH), and (c) hourly peak. Generalized additive models were fitted to estimate the excess risk (ER) associated with PM_2.5. A total of 105,639 ALRI (35,310 pneumonia and 68,218 bronchiolitis) outpatient visits were identified during the study period. An interquartile range increment in PM_2.5 DECH was consistently associated with the highest ER of ALRI-related outpatient visits: 12.30% (95% confidence interval [CI]: 9.49–15.18%), compared with 11.20% (95% CI: 8.34–14.13%) for daily mean and 9.73% (95% CI: 6.97–12.55%) for hourly peak. The associations between the three metrics of PM_2.5 and ALRI-related outpatient visits were stronger in the cold season than in the warm season. Future studies should consider PM_2.5 DECH as an alternative method of exposure measurement, in addition to daily mean and hourly peak concentrations of PM_2.5.

Characteristics of polycyclic aromatic hydrocarbons in ambient air of a tropical mega-area, Ho Chi Minh City, Vietnam: concentration, distribution, gas/particle partitioning, potential sources and cancer risk assessment

This is the first investigation on overall characteristics of 25 polycyclic aromatic hydrocarbons (PAHs) (15 PAHs regulated by US-EPA (excluding naphthalene) and 16 PAHs recommended by the European Union) in ambient air of Ho Chi Minh City, Vietnam. Their levels, congener profiles, gas/particle partitioning, potential sources of atmospheric PAHs (gas and particulate phases), and lung cancer risks in the dry and rainy seasons were examined. The ∑25 PAH concentration in the dry and rainy seasons ranged from 8.79 to 33.2 ng m^-3 and 26.0 to 60.0 ng m^-3, respectively. Phenanthrene and Indeno[123-cd]pyrene were major contributors to gaseous and particulate PAHs, respectively, while benzo[c]fluorene was dominant component of the total BaP-TEQ. The ∑16 EU-PAH concentration contributed to 13 ± 2.7% of the total ∑ 25 PAH concentration; however, they composed over 99% of the total ∑ 25 PAH toxic concentration. Adsorption mainly governed the phase partitioning of PAHs because the slope of correlation between logK_p and logP⁰_L was steeper than - 1. Vehicular emission was the primary source of PAHs in two seasons; however, PAHs in the dry season were also originated from biomass burning. Assessment of lung cancer risk showed that children possibly exposed to potential lung cancer risk via inhalation.

Three exposure metrics of size-specific particulate matter associated with acute lower respiratory infection hospitalization in children: A multi-city time-series analysis in China

BACKGROUND

The global burden of acute lower respiratory infection (ALRI) attributable to air pollution has increased in recent years, but the association between ALRI and exposure to size-specific particulate matter has not been investigated using different exposure metrics.

METHODS

We obtained ALRI admission from seven cities from 2014 to 2016 in China. Different sized particles were measured using three metrics (a) daily mean, (b) hourly peak, and (c) daily excessive concentration hours (DECH). Generalized additive models were fitted for each of the seven cities, and the city-specific estimates were then pooled using random-effects meta-analysis models. Stratified analyses were conducted to examine the effect modifications of gender, age, and season. We also estimated the disease burden due to particulate matter exposures.

RESULTS

There were 111,426 ALRI (79,803 pneumonia and 31,622 bronchiolitis) hospital admissions under the age of 15 between 2014 and 2016 in our study. Daily means were associated with the largest ALRI estimates (95% confidence interval [CI]): 2.43% (0.79%, 4.11%) for PM_2.5, 2.25% (0.11%, 4.44%) for PM_c, and 2.64% (0.73%, 4.58%) for PM₁₀. The magnitude of effect sizes were followed by DECH: 1.94% (0.51%, 3.39%) for PM_2.5, 0.88% (-0.14%, 1.92%) for PM_c, 1.86% (0.50%, 2.01%) for PM₁₀; and hourly peak: 0.70% (-0.60%, 2.01%) for PM_2.5, 1.05% (-0.13%, 2.66%) for PM_c, and 1.20% (-0.20%, 2.62%) for PM₁₀ at lag03. We found significantly higher effects in cold seasons than that in warm seasons, while we did not find a significant different between gender and age groups.

CONCLUSIONS

The adverse effects of exposure to particulate matter on ALRI hospitalizations are reconfirmed. DECH was a possible alternative exposure indicator for PM_2.5 assessment, which may affect air quality standards in the future.

Ambient air pollution and acute respiratory infection in children aged under 5 years living in 35 developing countries

BACKGROUND

Evidence from developed countries suggests that fine particulate matter (≤2.5 µm [PM_2.5]) contributes to childhood respiratory morbidity and mortality. However, few analyses have focused on resource-limited settings, where much of this burden occurs. We aimed to investigate the cross-sectional associations between annual average exposure to ambient PM_2.5 and acute respiratory infection (ARI) in children aged <5 years living in low- and middle-income countries (LMICs).

METHODS

We combined Demographic and Health Survey (DHS) data from 35 countries with gridded global estimates of annual PM_2.5 mass concentrations. We analysed the association between PM_2.5 and maternal-reported ARI in the two weeks preceding the survey among children aged <5 years living in 35 LMICs. We used multivariable logistic regression models that adjusted for child, maternal, household and cluster-level factors. We also fitted multi-pollutant models (adjusted for nitrogen dioxide [NO₂] and surface-level ozone [O₃]), among other sensitivity analyses. We assessed whether the associations between PM_2.5 and ARI were modified by sex, age and place of residence.

RESULTS

The analysis comprised 573,950 children, among whom the prevalence of ARI was 22,506 (3.92%). The mean (±SD) estimated annual concentration of PM_2.5 to which children were exposed was 48.2 (±31.0) µg/m³. The 5th and 95th percentiles of PM_2.5 were 9.8 µg/m³ and 110.9 µg/m³, respectively. A 10 µg/m³ increase in PM_2.5 was associated with greater odds of having an ARI (OR: 1.06; 95% CI: 1.05-1.07). The association between PM_2.5 and ARI was robust to adjustment for NO₂ and O₃. We observed evidence of effect modification by sex, age and place of residence, suggesting greater effects of PM_2.5 on ARI in boys, in younger children, and in children living in rural areas.

CONCLUSIONS

Annual average ambient PM_2.5, as an indicator for long-term exposure, was associated with greater odds of maternal-reported ARI in children aged <5 years living in 35 LMICs. Longitudinal studies in LMICs are required to corroborate our cross-sectional findings, to further elucidate the extent to which lowering PM_2.5 may have a role in the global challenge of reducing ARI-related morbidity and mortality in children.

Short-term effects of air pollution on respiratory diseases among young children in Wuhan city, China

BACKGROUND

The high risks for childhood respiratory diseases are associated with exposure to ambient air pollution. However, there are few studies that have explored the association between air pollution exposure and respiratory diseases among young children (particularly aged 0-2 years) based on the entire population in a megalopolis.

METHODS

Daily hospital admission records were obtained from 54 municipal hospitals in Wuhan city, China. We included all children (aged 0-2 years) hospitalized with respiratory diseases between January 2017 and December 2018. Individual air pollution exposure assessment was used in Land Use Regression model and inverse distance weighted. Case-crossover design and conditional logistic regression models were adopted to estimate the hospitalization risk associated with air pollutants.

RESULTS

We identified 62,425 hospitalizations due to respiratory diseases, of which 36,295 were pneumonia. Particulate matter with an aerodynamic diameter less than 2.5 μm (PM_2.5) and nitrogen dioxide (NO₂) were significantly associated with respiratory diseases and pneumonia. ORs of pneumonia were 1.0179 (95% CI 1.0097-1.0260) for PM_2.5 and 1.0131 (95% CI 1.0042-1.0220) for NO₂ at lag 0-7 days. Subgroup analysis suggested that NO₂, Ozone (O₃) and sulfur dioxide (SO₂) only showed effects on pneumonia hospitalizations on male patients, but PM_2.5 had effects on patients of both genders. Except O₃, all pollutants were strongly associated with pneumonia in cold season. In addition, children who aged elder months and who were in central urban areas had a higher hospitalization risk.

CONCLUSIONS

Air pollution is associated with higher hospitalization risk for respiratory diseases, especially pneumonia, among young children, and the risk is related to gender, month age, season and residential location.

Mortality benefits of reduction fine particulate matter in Vietnam, 2019

INTRODUCTION AND OBJECTIVES

Studies assessing the health benefits of air pollution reduction in Vietnam are scarce. This study quantified the annual mortality burden due to PM_2.5 pollution in Vietnam above the World Health Organization recommendation for community health (AQG: 5 μg/m³) and the proposed National Technical Regulation on Ambient Air Quality (proposed QCVN: 15 μg/m³).

METHODOLOGY

This study applied a health impact assessment methodology with the hazard risk function for non-communicable diseases (NCDs) and lower respiratory infections (LRIs) in the Global Exposure Mortality Model (GEMM) to calculate attributable deaths, Years of Life lost, and Loss of Life expectancy at birth due to air pollution in the Vietnamese population above 25 years of age in 11 provinces. We obtained annual average PM_2.5 concentrations for Vietnam in 2019 at a 3x3 km grid modeled using Mixed Linear regression and multi-data sources. Population and baseline mortality data were obtained from administrative data system in Vietnam. We reported the findings at both the provincial and smaller district levels.

RESULTS

Annual PM_2.5 concentrations in all studied provinces exceeded both the AQG and the proposed QCVN. The maximum annual number of attributable deaths in the studied provinces if they had complied with WHO air quality guidelines was in Ha Noi City, with 5,090 (95%CI: 4,253-5,888) attributable deaths. At the district level, the highest annual rate of attributable deaths if the WHO recommendation for community health had been met was 104.6 (95%CI: 87.0-121.5) attributable deaths per 100,000 population in Ly Nhan (Ha Nam province).

CONCLUSION

A much larger number of premature deaths in Vietnam could potentially be avoided by lowering the recommended air quality standard. These results highlight the need for effective clean air action plans by local authorities to reduce air pollution and improve community health.

Forecasting PM2.5 concentration using artificial neural network and its health effects in Ahvaz, Iran

The main objective of the present study was to predict the associated health endpoint of PM2.5 using an artificial neural network (ANN). The neural network used in this work contains a hidden layer with 27 neurons, an input layer with 8 parameters, and an output layer. First, the artificial neural network was implemented with 80% of data for training then with 90% of data for training. The value of R for the data validation of these two networks was 0.80 and 0.83 respectively. The World Health Organization AirQ + software was utilized for assessing Health effects of PM2.5 levels. The mean PM2.5 over the 9-year study period was 63.27(μg/m3), about six times higher than the WHO guideline. However, the PM2.5 concentration in the last year decreased by about 25% compared to the first year, which is statistically significant (P-value = 0.0048). This reduced pollutant concentration led to a decrease in the number of deaths from 1785 in 2008 to 1059 in 2016. Moreover, a positive correlation was found between PM2.5 concentration and temperature and wind speed. Considering the importance of predicting PM2.5 concentration for accurate and timely decisions as well as the accuracy of the artificial neural network used in this study, the artificial neural network can be utilized as an effective instrument to reduce health and economic effects.

Ambient Air Pollution and Respiratory Health in Sub-Saharan African Children: A Cross-Sectional Analysis

Ambient air pollution is projected to become a major environmental risk in sub-Saharan Africa (SSA). Research into its health impacts is hindered by limited data. We aimed to investigate the cross-sectional relationship between particulate matter with a diameter ≤ 2.5 μm (PM_2.5) and prevalence of cough or acute lower respiratory infection (ALRI) among children under five in SSA. Data were collected from 31 Demographic and Health Surveys (DHS) in 21 SSA countries between 2005–2018. Prior-month average PM_2.5 preceding the survey date was assessed based on satellite measurements and a chemical transport model. Cough and ALRI in the past two weeks were derived from questionnaires. Associations were analysed using conditional logistic regression within each survey cluster, adjusting for child’s age, sex, birth size, household wealth, maternal education, maternal age and month of the interview. Survey-specific odds ratios (ORs) were pooled using random-effect meta-analysis. Included were 368,366 and 109,664 children for the analysis of cough and ALRI, respectively. On average, 20.5% children had reported a cough, 6.4% reported ALRI, and 32% of children lived in urban areas. Prior-month average PM_2.5 ranged from 8.9 to 64.6 μg/m³. Pooling all surveys, no associations were observed with either outcome in the overall populations. Among countries with medium-to-high Human Development Index, positive associations were observed with both cough (pooled OR: 1.022, 95%CI: 0.982–1.064) and ALRI (pooled OR: 1.018, 95%CI: 0.975–1.064) for 1 μg/m³ higher of PM_2.5. This explorative study found no associations between short-term ambient PM_2.5 and respiratory health among young SSA children, necessitating future analyses using better-defined exposure and health metrics to study this important link.

Significance between air pollutants, meteorological factors, and COVID-19 infections: probable evidences in India

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease represents the causative agent with a potentially fatal risk which is having great global human health concern. Earlier studies suggested that air pollutants and meteorological factors were considered as the risk factors for acute respiratory infection, which carries harmful pathogens and affects the immunity. The study intended to explore the correlation between air pollutants, meteorological factors, and the daily reported infected cases caused by novel coronavirus in India. The daily positive infected cases, concentrations of air pollutants, and meteorological factors in 288 districts were collected from January 30, 2020, to April 23, 2020, in India. Spearman's correlation and generalized additive model (GAM) were applied to investigate the correlations of four air pollutants (PM2.5, PM10, NO2, and SO2) and eight meteorological factors (Temp, DTR, RH, AH, AP, RF, WS, and WD) with COVID-19-infected cases. The study indicated that a 10 μg/m3 increase during (Lag0-14) in PM2.5, PM10, and NO2 resulted in 2.21% (95%CI: 1.13 to 3.29), 2.67% (95% CI: 0.33 to 5.01), and 4.56 (95% CI: 2.22 to 6.90) increase in daily counts of Coronavirus Disease 2019 (COVID 19)-infected cases respectively. However, only 1 unit increase in meteorological factor levels in case of daily mean temperature and DTR during (Lag0-14) associated with 3.78% (95%CI: 1.81 to 5.75) and 1.82% (95% CI: -1.74 to 5.38) rise of COVID-19-infected cases respectively. In addition, SO2 and relative humidity were negatively associated with COVID-19-infected cases at Lag0-14 with decrease of 7.23% (95% CI: -10.99 to -3.47) and 1.11% (95% CI: -3.45 to 1.23) for SO2 and for relative humidity respectively. The study recommended that there are significant correlations between air pollutants and meteorological factors with COVID-19-infected cases, which substantially explain the effect of national lockdown and suggested positive implications for control and prevention of the spread of SARS-CoV-2 disease.

Impact of temperature on hospital admission for acute lower respiratory infection (ALRI) among pre-school children in Ho Chi Minh City, Vietnam

Changes in ambient temperature have been reported as an important risk factor for respiratory diseases among pre-school children. However, there have been few studies so far on the effects of temperature on children respiratory health in developing countries including Vietnam. This study examined the impact of short-term changes in ambient temperature on hospital admissions for acute lower respiratory infection (ALRI) among children aged less than 5 years old in Ho Chi Minh City (HCMC), Vietnam. Data on daily hospital admissions from 2013 to 2017 were collected from two large paediatric hospitals of the city. Daily meteorological data of the same period were also collected. Time series analysis was performed to evaluate the association between risk of hospitalisations and temperatures categorised by seasons, age, and causes. We found that a 1 °C increase in maximum temperature was associated with 4.2 and 3.4% increase in hospital admission for ALRI among children 3-5 years old during the dry season and the rainy season, respectively. Surprisingly, in the rainy season, a rise of 1°C diurnal temperature range (DTR) was significantly associated with a decrease from 2.0 to 2.5% risk of hospitalisation for ALRI among children <3 years old. These findings suggested that although high temperature is a risk factor for hospital admissions among children in general, other modifiable factors such as age, exposure time, air conditioning usage, wearing protective clothing, socioeconomic status, and behaviour may influence the overall effect of high temperature on hospital admissions of children <5 years old in HCMC. The findings of this study have provided evidence for building public health policies aimed at preventing and minimizing the adverse health effects of temperature on children in HCMC.

The Influence of Air Pollutants and Meteorological Conditions on the Hospitalization for Respiratory Diseases in Shenzhen City, China

Air pollutants have significant direct and indirect adverse effects on public health. To explore the relationship between air pollutants and meteorological conditions on the hospitalization for respiratory diseases, we collected a whole year of daily major air pollutants’ concentrations from Shenzhen city in 2013, including Particulate Matter (PM₁₀, PM_2.5), Nitrogen dioxide (NO₂), Ozone (O₃), Sulphur dioxide (SO₂), and Carbon monoxide (CO). Meanwhile, we also gained meteorological data. This study collected 109,927 patients cases with diseases of the respiratory system from 98 hospitals. We investigated the influence of meteorological factors on air pollution by Spearman correlation analysis. Then, we tested the short-term correlation between significant air pollutants and respiratory diseases’ hospitalization by Distributed Lag Non-linear Model (DLNM). There was a significant negative correlation between the north wind and NO₂ and a significant negative correlation between the south wind and six pollutants. Except for CO, other air pollutants were significantly correlated with the number of hospitalized patients during the lag period. Most of the pollutants reached maximum Relative Risk (RR) with a lag of five days. When the time lag was five days, the annual average of PM₁₀, PM_2.5, SO₂, NO₂, and O₃ increased by 10%, and the risk of hospitalization for the respiratory system increased by 0.29%, 0.23%, 0.22%, 0.25%, and 0.22%, respectively. All the pollutants except CO impact the respiratory system’s hospitalization in a short period, and PM10 has the most significant impact. The results are helpful for pollution control from a public health perspective.

Particulate air pollution and respiratory Haemophilus influenzae infection in Mianyang, southwest China

Particulate air pollution is correlated with many respiratory diseases. However, few studies have focused on the relationship between air particulate exposure and respiratory Heamophilus influenzae infection. Therefore, we detected respiratory Heamophilus influenzae infection by bacterial culture of sputum of patients, and we collected particulate air pollution data (including PM2.5 and PM10) from a national real-time urban air quality platform to analyze the relationship between particulate air pollution and respiratory Heamophilus influenzae infection. The mean concentrations of PM2.5 and PM10 were 37.58 μg/m3 and 58.44 μg/m3, respectively, showing particulate air pollution remains a severe issue in Mianyang. A total of 828 strains of Heamophilus influenzae were detected in sputum by bacterial culture. Multiple correspondence analysis suggested the heaviest particulate air pollution and the highest Heamophilus influenzae infection rates were all in winter, while the lowest particulate air pollution and the lowest Heamophilus influenzae infection rates were all in summer. In a single-pollutant model, each elevation of 10 μg/m3 of PM2.5, PM10, and PM2.5/10 (combined exposure level) increased the risk of respiratory Heamophilus influenzae infection by 34%, 23%, and 29%, respectively. Additionally, in the multiple-pollutant model, only PM2.5 was significantly associated with respiratory Heamophilus influenzae infection (B, 0.46; 95% confidence interval, 0.05-0.87), showing PM2.5 is an independent risk factor for respiratory Heamophilus influenzae infection. In summary, this study highlights air particulate exposure could increase the risk of respiratory Heamophilus influenzae infection, implying that stronger measures need to be taken to protect against respiratory infection induced by particulate air pollution.

The effect of air pollution on immunological, antioxidative and hematological parameters, and body condition of Eurasian tree sparrows

Air pollution constitutes potential threats to wildlife and human health; therefore, it must be monitored accurately. However, little attention has been given to understanding the toxicological effects induced by air pollution and the suitability of bird species as bioindicators. The Eurasian tree sparrow (Passer montanus), a human commensal species, was used as a study model to examine toxic metal accumulation, retention of particulate matter (PM), immunological and antioxidant capacities, and hematological parameters in birds inhabiting those areas with relatively higher (Shijiazhuang city) or lower (Chengde city) levels of PM_2.5 and PM₁₀ in China. Our results showed that Shijiazhuang birds had significantly more particle retention in the lungs and toxic metal (including aluminum, arsenic, cadmium, iron, manganese, and lead) accumulation in the feathers relative to Chengde birds. They also had lower superoxide dismutase, albumin, immunoglobulin M concentrations in the lung lavage fluid, and total antioxidant capacity (T-AOC) in the lungs and hearts. Furthermore, although they had higher proportions of microcytes, hypochromia, and polychromatic erythrocytes in the peripheral blood (a symptom of anemia), both populations exhibited comparable body conditions, white cell counts, heterophil and lymphocyte ratios, and plasma T-AOC and corticosterone levels. Therefore, our results not only confirmed that Shijiazhuang birds experienced a greater burden from environmental PM and toxic metals but also identified a suite of adverse effects of environmental pollution on immunological, antioxidative, and hematological parameters in multiple tissues. These findings contribute to our understanding of the physiological health consequences induced by PM exposure in wild animals. They suggest that free-living birds inhabiting urban areas could be used as bioindicators for evaluating the adverse effects induced by environmental pollution.

Exceedances and trends of particulate matter (PM2.5) in five Indian megacities

Fine particulate matter (PM_2.5) is the leading environmental risk factor that requires regular monitoring and analysis for effective air quality management. This work presents the variability, trend, and exceedance analysis of PM_2.5 measured at US Embassy and Consulate in five Indian megacities (Chennai, Kolkata, Hyderabad, Mumbai, and New Delhi) for six years (2014-2019). Among all cities, Delhi is found to be the most polluted city followed by Kolkata, Mumbai, Hyderabad, and Chennai. The trend analysis for six years for five megacities suggests a statistically significant decreasing trend ranging from 1.5 to 4.19 μg/m³ (2%-8%) per year. Distinct diurnal, seasonal, and monthly variations are observed in the five cities due to the different site locations and local meteorology. All cities show the highest and lowest concentrations in the winter and monsoon months respectively except for Chennai which observed the lowest levels in April. All the cities consistently show morning peaks (~08: 00-10:00 h) and the lowest level in late afternoon hours (~15:00-16:00 h). We found that the PM_2.5 levels in the cities exceed WHO standards and Indian NAAQS for 50% and 33% of days in a year except for Chennai. Delhi is found to have more than 200 days of exceedances in a year and experiences an average 15 number of episodes per year when the level exceeds the Indian NAAQS. The trends in the exceedance with a varying threshold (20-380 μg/m³) suggest that not only is the annual mean PM_2.5 decreasing in Delhi but also the number of exceedances is decreasing. This decrease can be attributed to the recent policies and regulations implemented in Delhi and other cities for the abatement of air pollution. However, stricter compliance of the National Clean Air Program (NCAP) policies can further accelerate the reduction of the pollution levels.

Short-Term Exposure to Fine Particulate Matter and Hospitalizations for Acute Lower Respiratory Infection in Korean Children: A Time-Series Study in Seven Metropolitan Cities

Although several studies have evaluated the association between fine particulate matter (PM_2.5) and acute lower respiratory infection (ALRI) in children, their results were inconsistent Therefore, we aimed to evaluate the association between short-term exposure to PM_2.5 and ALRI hospitalizations in children (0–5 years) living in seven metropolitan cities of Korea. The ALRI hospitalization data of children living in seven metropolitan cities of Korea from 2008 to 2016 was acquired from a customized database constructed based on National Health Insurance data. The time-series data in a generalized additive model were used to evaluate the relationship between ALRI hospitalization and 7-day moving average PM_2.5 exposure after adjusting for apparent temperature, day of the week, and time trends. We performed a meta-analysis using a two-stage design method. The estimates for each city were pooled to generate an average estimate of the associations. The average PM_2.5 concentration in 7 metropolitan cities was 29.0 μg/m³ and a total of 713,588 ALRI hospitalizations were observed during the 9-year study period. A strong linear association was observed between PM_2.5 and ALRI hospitalization. A 10 μg/m³ increase in the 7-day moving average of PM_2.5 was associated with a 1.20% (95% CI: 0.71, 1.71) increase in ALRI hospitalization. While we found similar estimates in a stratified analysis by sex, we observed stronger estimates of the association in the warm season (1.71%, 95% CI: 0.94, 2.48) compared to the cold season (0.31%, 95% CI: −0.51, 1.13). In the two-pollutant models, the PM_2.5 effect adjusted by SO₂ was attenuated more than in the single pollutant model. Our results suggest a positive association between PM_2.5 exposure and ALRI hospitalizations in Korean children, particularly in the warm season. The children need to refrain from going out on days when PM_2.5 is high.

Short term effects of air pollutants on hospital admissions for respiratory diseases among children: A multi-city time-series study in China

Evidence concerning short-term acute association between air pollutants and hospital admissions for respiratory diseases among children in a multi-city setting was quite limited. We conducted a time-series analysis to evaluate the association of six common air pollutants with hospital admissions for respiratory diseases among children aged 0-14 years in 4 cities (Guangzhou, Shanghai, Wuhan and Xining), China during 2013-2018. We used generalized additive models incorporating penalized smoothing splines and random-effect meta-analysis to calculate city-specific and pooled estimates, respectively. The exposure-response relationship curves were fitted using the cubic spline regression. Subgroup analyses by gender, age, season and disease subtype were also performed. A total of 183,036 respiratory diseases hospitalizations were recorded during the study period, and 94.1% of the cases were acute respiratory infections. Overall, we observed that increased levels of air pollutants except O₃, were significantly associated with increased hospital admissions for respiratory disease. Each 10 μg/m³ increase in PM_2.5, SO₂ and NO₂ at lag 07, PM₁₀ at lag 03 and per 1 mg/m³ increase in CO at lag 01 corresponded to increments of 1.19%, 3.58%, 2.23%, 0.51% and 6.10% in total hospitalizations, respectively. Generally, exposure-response relationships of PM_2.5 and SO₂ in Guangzhou, SO₂, NO₂ and CO in Wuhan, as well as SO₂ and NO₂ in Xining with respiratory disease hospitalizations were also found. Moreover, the adverse effects of these pollutants apart from PM_2.5 in certain cities remained significant even at exposure levels below the current Chinese Ambient Air Quality Standards (CAAQS) Grade II. Children aged 4-14 years appeared to be more vulnerable to the adverse effects of PM_2.5, SO₂ and NO₂. Furthermore, with the exception of O₃, the associations were stronger in cold season than in warm season. Short-term exposure to PM_2.5, SO₂, NO₂ and CO were associated, in dose-responsive manners, with increased risks of hospitalizations for childhood respiratory diseases, and adverse effects of air pollutants except PM_2.5 held even at exposure levels below the current CAAQS Grade II in certain cities.

Study loading capacties of air pollutant emissions for developing countries: a case of Ho Chi Minh City, Vietnam

Ho Chi Minh City (HCMC) is one of the cities in developing countries where many concentrations of air pollutants exceeded the Vietnam national technical regulation in ambient air quality including TSP, NOx, Ozone and CO. These high pollutant concentrations have destroyed the human health of people in HCMC. Many zones in HCMC can't receive more air pollutants. The objectives of this research are: (i) Air quality modeling over HCMC by using the TAPM-CTM system model by using a bottom up air emission inventory; and (ii) Study loading capactities of air pollutant emissions over Ho Chi Minh City. Simulations of air pollution were conducted in Ho Chi Minh City (HCMC), the largest city of Vietnam by using the TAPM-CTM model. The model performance was evaluated using observed meteorological data at Tan Son Hoa station and air quality data at the Ho Chi Minh City University of Science. The model is then applied to simulate a retire 1-year period to determine the levels of air pollutants in HCMC in 2017, 2025 and 2030. The results show that the highest concentrations of CO, NO2, and O3 in 2017 exceeded the National technical regulation in ambient air quality (QCVN 05:2013) 1.5, 1.5, and 1.1 times, respectively. These values also will increase in 2025 and 2030 if the local government does not have any plan for the reduction of emissions, especially, SO2 in 2030 also will be 1.02 times higher than that in QCVN 05:2013. The emission zoning was initially studied by calculating and simulating the loading capacities of each pollutant based on the highest concentration and the National technical regulation in ambient air quality. The results show that the center of HCMC could not receive anymore the emission, even needs to reduce half of the emission. Under the easterly prevailing wind in the dry season, the high pollution was more likely to be experienced in the west of Ho Chi Minh. In contrast, the eastern regions were the upwind areas and the pollutants could transport to the downwind sectors. It was recommended that the best strategy for emission control in HCMC is avoiding industrial and urban development in the upwind areas to achieve better air quality for both areas. In the case of necessity to choose one area for development, the downwind sector is preferred. The results show that TAPM-CTM performed well as applied to simulate the air quality in HCMC and is a promising tool to study the emission zoning.