Ultrafine and Fine Particles and Hospital Admissions in Central Europe. Results from the UFIREG Study

Ultrafine Particles and Hospital Visits for Chronic Lower Respiratory Diseases in New York State

Rationale: Exposure to particulate matter is associated with various adverse health outcomes. Ultrafine particles (UFPs; diameter <0.1 μm) are a unique public health challenge because of their size. However, limited studies have examined their impacts on human health, especially across seasons and demographic characteristics. Objectives: To evaluate the effect of UFP exposure on the risk of visiting the emergency department (ED) for a chronic lower respiratory disease (CLRD) in New York State in 2013-2018. Methods: We used a case-crossover design and conditional logistic regression to estimate how UFP exposure led to CLRD-related ED visits. GEOS-Chem Advanced Particle Microphysics, a state-of-the-art chemical transport model with a size-resolved particle microphysics model, generated air pollution simulation data. We then matched UFP exposure estimates to geocoded health records for asthma, bronchiectasis, chronic bronchitis, emphysema, unspecified bronchitis, and other chronic airway obstructions in New York State from 2013 through 2018. In addition, we assessed interactions with age, ethnicity, race, sex, meteorological factors, and season. Results: Each 1-(interquartile range [IQR]) increase in UFP exposure led to a 0.37% increased risk of a respiratory-related ED visit on lag 0-0, or the day of the ED visits, (95% confidence interval [CI], 0.23-0.52%) and a 1.81% increase on lag 0-6, or 6 days before the ED visit, (95% CI, 1.58-2.03%). The highest risk was in the emphysema subtype (lag 0-5, 4.18%; 95% CI, 0.16-8.37%), followed by asthma (lag 0-6, 2.00%), chronic bronchitis (lag 0-6, 1.78%), other chronic airway obstructions (lag 0-6, 1.60%), and unspecified bronchitis (lag 0-6, 1.49%). We also found significant interactions between UFP health impacts and season (Fall, 3.29%), temperature (<90th percentile, 2.27%), relative humidity (>90th percentile, 4.63%), age (children aged <18 yr, 3.19%), and sex (men, 2.06%) on lag 0-6. Conclusions: In this study, UFP exposure increased CLRD-related ED visits across all seasons and demographic characteristics, yet these associations varied according to various factors, which requires more research.

Joint Effect of Short-Term Exposure to Fine Particulate Matter and Ozone on Mortality: A Time Series Study in 272 Chinese Cities

Short-term exposure to PM2.5 or O3 can increase mortality risk; however, limited studies have evaluated their interaction. A multicity time series study was conducted to investigate the synergistic effect of PM2.5 and O3 on mortality in China, using mortality data and high-resolution pollutant predictions from 272 cities in 2013-2015. Generalized additive models were applied to estimate associations of PM2.5 and O3 with mortality. Modification and interaction effects were explored by stratified analyses and synergistic indexes. Deaths attributable to PM2.5 and O3 were evaluated with or without modification of the other pollutant. The risk of total nonaccidental mortality increased by 0.70% for each 10 μg/m3 increase in PM2.5 when O3 levels were high, compared to 0.12% at low O3 levels. The effect of O3 on total nonaccidental mortality at high PM2.5 levels (1.26%) was also significantly higher than that at low PM2.5 levels (0.59%). Similar patterns were observed for cardiovascular or respiratory diseases. The relative excess risk of interaction and synergy index of PM2.5 and O3 on nonaccidental mortality were 0.69% and 1.31 with statistical significance, respectively. Nonaccidental deaths attributable to short-term exposure of PM2.5 or O3 when considering modification of the other pollutant were 28% and 31% higher than those without considering modification, respectively. Our results found synergistic effects of short-term coexposure to PM2.5 and O3 on mortality and suggested underestimations of attributable risks without considering their synergistic effects.

Associations between ultrafine particle pollution and daily outpatient visits for respiratory diseases in Shanghai, China: a time-series analysis

Previous epidemiological studies have linked short-term exposure to particulate matter with outpatient visits for respiratory diseases. However, evidence on ultrafine particle (UFP) is still scarce in China. To investigate the association between short-term UFP exposure and outpatient visits for respiratory diseases as well as the corresponding lag patterns, information on outpatient visits for main respiratory diseases during January 1, 2017, to December 31, 2019 was collected from electronic medical records of two large tertiary hospitals in Shanghai, China. Generalized additive models employing a Quasi-Poisson distribution were employed to investigate the relationships between UFP and respiratory diseases. We computed the percentage change and its corresponding 95% confidence interval (CI) for outpatient visits related to respiratory diseases per interquartile range (IQR) increase in UFP concentrations. Based on a total of 1,034,394 hospital visits for respiratory diseases in Shanghai, China, we found that the strongest associations of total UFP with acute upper respiratory tract infection (AURTI), bronchitis, chronic obstructive pulmonary disease (COPD), and pneumonia occurred at lag 03, 03, 0, and 03 days, respectively. Each IQR increase in the total UFP concentrations was associated with increments of 9.02% (95% CI: 8.64-9.40%), 3.94% (95% CI: 2.84-5.06%), 4.10% (95% CI: 3.01-5.20%), and 10.15% (95% CI: 9.32-10.99%) for AURTI, bronchitis, COPD, and pneumonia, respectively. Almost linear concentration-response relationship curves without apparent thresholds were observed between total UFP and outpatient-department visits for four respiratory diseases. Stratified analyses illustrated significantly stronger associations of total UFP with AURTI, bronchitis, and pneumonia among female patients, while that with COPD was stronger among male patients. After adjustment of criteria air pollutants, these associations all remained robust. This time-series study indicates that short-term exposure to UFP was associated with increased risk of hospital visits for respiratory diseases, underscoring the importance of reducing ambient UFP concentrations for respiratory diseases control and prevention.

Short-term exposure to ultrafine particles and mortality and hospital admissions due to respiratory and cardiovascular diseases in Copenhagen, Denmark

Ultrafine particles (UFP; particulate matter <0.1 μm in diameter) may be more harmful to human health than larger particles, but epidemiological evidence on their health effects is still limited. In this study, we examined the association between short-term exposure to UFP and mortality and hospital admissions in Copenhagen, Denmark. Daily concentrations of UFP (measured as particle number concentration in a size range 11-700 nm) and meteorological variables were monitored at an urban background station in central Copenhagen during 2002-2018. Daily counts of deaths from all non-accidental causes, as well as deaths and hospital admissions from cardiovascular and respiratory diseases were obtained from Danish registers. Mortality and hospital admissions associated with an interquartile range (IQR) increase in UFP exposure on a concurrent day and up to six preceding days prior to the death or admission were examined in a case-crossover study design. Odds ratios (OR) with 95% confidence intervals (CI) per one IQR increase in UFP were estimated after adjusting for temperature and relative humidity. We observed 140,079 deaths in total, 236,003 respiratory and 342,074 cardiovascular hospital admissions between 2002 and 2018. Hospital admissions due to respiratory and cardiovascular diseases were significantly positively associated with one IQR increase in UFP (OR: 1.04 [95% CI: 1.01, 1.07], lag 0-4, and 1.02 [1.00, 1.04], lag 0-1, respectively). Among the specific causes, the strongest associations were found for chronic obstructive pulmonary disease (COPD) mortality and asthma hospital admissions and two-day means (lag 0-1) of UFP (OR: 1.13 [1.01, 1.26] and 1.08 [1.00, 1.16], respectively, per one IQR increase in UFP). Based on 17 years of UFP monitoring data, we present novel findings showing that short-term exposure to UFP can trigger respiratory and cardiovascular diseases mortality and morbidity in Copenhagen, Denmark. The strongest associations with UFP were observed with COPD mortality and asthma hospital admissions.

Impact of ultrafine particles and total particle number concentration on five cause-specific hospital admission endpoints in three German cities

INTRODUCTION

Numerous studies have shown associations between daily concentrations of fine particles (e.g., particulate matter with an aerodynamic diameter ≤2.5 µm; PM2.5) and morbidity. However, evidence for ultrafine particles (UFP; particles with an aerodynamic diameter of 10-100 nm) remains conflicting. Therefore, we aimed to examine the short-term associations of UFP with five cause-specific hospital admission endpoints for Leipzig, Dresden, and Augsburg, Germany.

MATERIAL AND METHODS

We obtained daily counts of (cause-specific) cardiorespiratory hospital admissions between 2010 and 2017. Daily average concentrations of UFP, total particle number (PNC; 10-800 nm), and black carbon (BC) were measured at six sites; PM2.5 and nitrogen dioxide (NO2) were obtained from monitoring networks. We assessed immediate (lag 0-1), delayed (lag 2-4, lag 5-7), and cumulative (lag 0-7) effects by applying station-specific confounder-adjusted Poisson regression models. We then used a novel multi-level meta-analytical method to obtain pooled risk estimates. Finally, we performed two-pollutant models to investigate interdependencies between pollutants and examined possible effect modification by age, sex, and season.

RESULTS

UFP showed a delayed (lag 2-4) increase in respiratory hospital admissions of 0.69% [95% confidence interval (CI): -0.28%; 1.67%]. For other hospital admission endpoints, we found only suggestive results. Larger particle size fractions, such as accumulation mode particles (particles with an aerodynamic diameter of 100-800 nm), generally showed stronger effects (respiratory hospital admissions & lag 2-4: 1.55% [95% CI: 0.86%; 2.25%]). PM2.5 showed the most consistent associations for (cardio-)respiratory hospital admissions, whereas NO2 did not show any associations. Two-pollutant models showed independent effects of PM2.5 and BC. Moreover, higher risks have been observed for children.

CONCLUSIONS

We observed clear associations with PM2.5 but UFP or PNC did not show a clear association across different exposure windows and cause-specific hospital admissions. Further multi-center studies are needed using harmonized UFP measurements to draw definite conclusions on the health effects of UFP.

The spatial-temporal effect of air pollution on individuals' reported health and its variation by ethnic groups in the United Kingdom: a multilevel longitudinal analysis

BACKGROUND

Air pollution is associated with poor health; though it is unclear whether this association is stronger for ethnic minorities compared to the rest of the population. This study uses longitudinal data to investigate the spatial-temporal effect of air pollution on individuals' reported health and its variation by ethnicity in the United-Kingdom (UK).

METHODS

Longitudinal individual-level data from Understanding Society: the UK Household Longitudinal Study including 67,982 adult individuals with 404,264 repeated responses over 11 years (2009-2019) were utilized and were linked to yearly concentrations of NO₂, SO₂, and particulate-matter (PM10, PM2.5) pollution once at the local authority and once at the census Lower Super Output Area (LSOA) of residence for each individual. This allows for analysis at two geographical scales over time. The association between air pollution and individuals' health (Likert scale: 1-5, Excellent to poor) and its variation by ethnicity was assessed using three-level mixed-effects ordered logistic models. Analysis distinguished between spatial (between areas) and temporal (across time within each area) effects of air pollution on health.

RESULTS

Higher concentrations of NO₂, SO₂, PM10, and PM2.5 pollution were associated with poorer health. Decomposing air pollution into between (spatial: across local authorities or LSOAs) and within (temporal: across years within each local authority or LSOA) effects showed a significant between effect for NO₂ and SO₂ pollutants at both geographical scales, while a significant between effect for PM10 and PM2.5 was shown only at the LSOAs level. No significant within effects were detected at an either geographical level. Indian, Pakistani/Bangladeshi, Black/African/Caribbean and other ethnic groups and non-UK-born individuals reported poorer health with increasing concentrations of NO₂, SO₂, PM10, and PM2.5 pollutants in comparison to the British-white and UK-born individuals.

CONCLUSION

Using longitudinal data on individuals' health linked with air pollution data at two geographical scales (local authorities and LSOAs), this study supports the presence of a spatial-temporal association between air pollution and poor self-reported health, which is stronger for ethnic minorities and foreign-born individuals in the UK, partly explained by location-specific differences. Air pollution mitigation is necessary to improve individuals' health, especially for ethnic minorities who are affected the most.

Kinetics of autophagic activity in nanoparticle-exposed lung adenocarcinoma (A549) cells

Autophagy, a homeostatic mechanism, is crucial in maintaining normal cellular function. Although dysregulation of autophagic processes is recognized in certain diseases, it is unknown how maintenance of cellular homeostasis might be affected by the kinetics of autophagic activity in response to various stimuli. In this study, we assessed those kinetics in lung adenocarcinoma (A549) cells in response to exposure to nanoparticles (NP) and/or Rapamycin. Since NP are known to induce autophagy, we wished to determine if this phenomenon could be a driver of the harmful effects seen in lung tissues exposed to air pollution. A549 cells were loaded with a fluorescent marker (DAPRed) that labels autophagosomes and autolysosomes. Autophagic activity was assessed based on the fluorescence intensity of DAPRed measured over the entire cell volume of live single cells using confocal laser scanning microscopy (CLSM). Autophagic activity over time was determined during exposure of A549 cells to single agents (50 nM Rapamycin; 80 μg/mL, 20 nm carboxylated polystyrene NP (PNP); or, 1 μg/mL ambient ultrafine particles (UFP) (<180 nm)), or double agents (Rapamycin + PNP or Rapamycin + UFP; concomitant and sequential), known to stimulate autophagy. Autophagic activity increased in all experimental modalities, including both single agent and double agent exposures, and reached a steady state in all cases ~2 times control from ~8 to 24 hrs, suggesting the presence of an upper limit to autophagic capacity. These results are consistent with the hypothesis that environmental stressors might exert their harmful effects, at least in part, by limiting available autophagic response to additional stimulation, thereby making nanoparticle-exposed cells more susceptible to secondary injury due to autophagic overload.

Fine particulate matter and cardiorespiratory health in China: A systematic review and meta-analysis of epidemiological studies

This review aimed to systematically summarize the epidemiological literature on the cardiorespiratory effects of PM_2.5 published during the 13^th Five-Year Plan period (2016-2020) in China. Original articles published between January 1, 2016 and June 30, 2021 were searched in PubMed, Web of Science, the China National Knowledge Internet Database and Wanfang Database. Random- or fixed-effects models were used to pool effect estimates where appropriate. Of 8558 records identified, 145 met the full eligibility criteria. A 10 µg/m³ increase in short-term PM_2.5 exposure was significantly associated with increases of 0.70%, 0.86%, 0.38% and 0.96% in cardiovascular mortality, respiratory mortality, cardiovascular morbidity, and respiratory morbidity, respectively. The specific diseases with significant associations included stroke, ischemic heart disease, heart failure, arrhythmia, chronic obstructive pulmonary disease, pneumonia and allergic rhinitis. The pooled estimates per 10 µg/m³ increase in long-term PM_2.5 exposure were 15.1%, 11.9% and 21.0% increases in cardiovascular, stroke and lung cancer mortality, and 17.4%, 11.0% and 4.88% increases in cardiovascular, hypertension and lung cancer incidence respectively. Adverse changes in blood pressure, heart rate variability, systemic inflammation, blood lipids, lung function and airway inflammation were observed for either short-term or long-term PM_2.5 exposure, or both. Collectively, we summarized representative exposure-response relationships between short- and long-term PM_2.5 exposure and a wide range of cardiorespiratory outcomes applicable to China. The magnitudes of estimates were generally smaller in short-term associations and comparable in long-term associations compared with those in developed countries. Our findings are helpful for future standard revisions and policy formulation. There are still some notable gaps that merit further investigation in China.

Size-segregated particle number concentrations and outpatient-department visits for pediatric respiratory diseases in Shanghai, China

BACKGROUND

Few studies have simultaneously explored which size of particles has the greatest impact on the risk for pediatric asthma, bronchitis and upper respiratory tract infections (URTIs).

OBJECTIVES

To investigate the short-term association between size-segregated particle number concentrations (PNCs) and outpatient-department visits (ODVs) for major pediatric respiratory diseases.

METHODS

Daily counts of pediatric ODVs for asthma, bronchitis and URTIs were obtained from 66 hospitals in Shanghai, China, from 2016 to 2018. Pollutant effects were estimated using Poisson generalized additive models combined with polynomial distributed lag models. We also fitted co-pollutant cumulative effects models included six criteria air pollutants and conducted stratifying analyses by gender, age, season and geographic distances.

RESULTS

We identified a total of 430,103 patients with asthma, 1,547,013 patients with bronchitis, and 2,155,738 patients with URTIs from the hospitals. Effect estimates increased with decreasing particle size. Ultrafine particle (UFP) and PNCs of 0.10-0.40 µm particles (PNC_0.10-0.40) were associated with increased ODVs for asthma, bronchitis and URTIs at cumulative lags up to 3d. Associations tended to appear stable after adjusting for criteria air pollutants. At the cumulative lag 0-2d, each interquartile range increase in UFP was associated with increased ODVs due to asthma (relative risk 1.21, 95% CI: 1.07, 1.38), bronchitis (1.20, 95% CI: 1.07, 1.34) and URTI (1.17, 95% CI: 1.06, 1.30), whereas the associations for PNC_0.10-0.40 remained significant but attenuated in magnitude.

CONCLUSIONS

UFP may be a leading contributor to the adverse respiratory effects of particulate air pollution and the effects increased with decreasing particle size.

Effect modification by sex for associations of fine particulate matter (PM2.5) with cardiovascular mortality, hospitalization, and emergency room visits: systematic review and meta-analysis

Particulate matter with aerodynamic diameter no larger than 2.5 μm (PM2.5) has been linked to cardiovascular diseases (CVDs) but evidence for vulnerability by sex remains unclear. We performed systematic review and meta-analysis to synthesize the state of scientific evidence on whether cardiovascular risks from PM2.5 differ for men compared to women. The databases Pubmed, Scopus, Embase, and GreenFILE were searched for studies published Jan. 1995 to Feb. 2020. Observational studies conducting subgroup analysis by sex for impacts of short-term or long-term exposure to PM2.5 on target CVDs were included. Data were independently extracted in duplicate and pooled with random-effects meta-regression. Risk ratios (RRs) for long-term exposure and percent changes in outcomes for short-term exposure were calculated per 10 μg/m3 PM2.5 increase. Quality of evidence of risk differences by sex was rated following Grading of Recommendations Assessment, Development and Evaluation (GRADE). A total of 12,502 articles were screened, with 61 meeting inclusion criteria. An additional 32 studies were added from citation chaining. RRs of all CVD mortality for long-term PM2.5 for men and women were the same (1.14; 95% CI: 1.09, 1.22) indicating no statistically different risks. Men and women did not have statistically different risks of daily CVD mortality, hospitalizations from all CVD, ischemic heart disease, cardiac arrest, acute myocardial infarction, and heart failure from short-term PM2.5 exposure (difference in % change in risk per 10 μg/m3 PM2.5: 0.04 (95% CI, -0.42 to 0.51); -0.05 (-0.47 to 0.38); 0.17 (-0.90, 1.24); 1.42 (-1.06, 3.97); 1.33 (-0.05, 2.73); and -0.48 (-1.94, 1.01), respectively). Analysis using GRADE found low or very low quality of evidence for sex differences for PM2.5-CVD risks. In conclusion, this meta-analysis and quality of evidence assessment of current observational studies found very limited evidence of the effect modification by sex for effects of PM2.5 on CVD outcomes in adults, which can inform clinical approaches and policies.

Longitudinal relationship of particulate matter and metabolic control and severe hypoglycaemia in children and adolescents with type 1 diabetes

BACKGROUND

Evidence for the metabolic impact of long-term exposure to air pollution on diabetes is lacking. We investigated the association of particulate matter <10 μm (PM₁₀) and <2.5 μm (PM_2.5) with yearly averages of HbA1c, daily insulin dose (IU/kg) and rates of severe hypoglycaemia in type 1 diabetes (T1D).

METHODS

We studied data of 44,383 individuals with T1D < 21 years which were documented in 377 German centres within the diabetes prospective follow-up registry (DPV) between 2009 and 2018. Outcomes were aggregated by year and by patient. PM₁₀-and PM_2.5-yearly averages prior to the respective treatment year were linked to individuals via the five-digit postcode areas of residency. Repeated measures linear and negative binomial regression were used to study the association between PM-quartiles (Q1 lowest, Q4 highest concentration) and yearly averages of HbA1c, daily insulin dose and rates of severe hypoglycaemia (confounders: sex, time-dependent age, age at diabetes onset, time-dependent type of treatment, migratory background, degree of urbanisation and socioeconomic index of deprivation).

RESULTS

Adjusted mean HbA1c increased with PM₁₀ (Q1: 7.96% [95%-CI: 7.95-7.98], Q4: 8.03% [8.02-8.05], p-value<0.001) and with PM_2.5 (Q1: 7.97% [7.95-7.99], Q4: 8.02% [8.01-8.04], p < 0.001). Changes in daily insulin dose were inversely related to PM (PM₁₀ and PM_2.5: Q1 0.85 IU/kg [0.84-0.85], Q4: 0.83 IU/kg [0.82-0.83], p < 0.001). Adjusted rates of severe hypoglycaemia increased with PM-quartile groups (PM₁₀ Q1:11.2 events/100 PY [10.9-11.5], PM₁₀ Q4: 15.3 [14.9-15.7], p < 0.001; PM_2.5 Q1: 9.9 events/100 PY [9.6-10.2], PM_2.5 Q4: 14.2 [13.9-14.6], p < 0.001).

DISCUSSION

Air pollution was associated with higher HbA1c levels and increased risk of severe hypoglycaemia in people with T1D, consequently indicating a higher risk of diabetes complications. Further studies are needed to explore causal pathways of the observed associations.

Acute exposure to PM2.5 triggers lung inflammatory response and apoptosis in rat

Severe haze events, especially with high concentration of fine particulate matter (PM_2.5), are frequent in China, which have gained increasing attention among public. The purpose of our study was explored the toxic effects and potential damage mechanisms about PM_2.5 acute exposure. Here, the diverse dosages of PM_2.5 were used to treat SD rats and human bronchial epithelial cell (BEAS-2B) for 24 h, and then the bioassays were performed at the end of exposure. The results show that acute exposure to diverse dosages of PM_2.5 could trigger the inflammatory response and apoptosis. The severely oxidative stress may contribute to the apoptosis. Also, the activation of Nrf2-ARE pathway was an important compensatory process of antioxidant damage during the early stage of acute exposure to PM_2.5. Furthermore, the HO-1 was suppression by siRNA that promoted cell apoptosis triggered by PM_2.5. In other words, enhancing the expression of HO-1 may mitigate the cell apoptosis caused by acute exposure to PM_2.5. In summary, our findings present the first time that prevent or mitigate the damage triggered by PM_2.5 through antioxidant approaches was a promising strategy.

MUC5B regulates the airway inflammation induced by atmospheric PM2.5 in rats and A549 cells

Atmospheric PM_2.5 can induce airway inflammation and mucin secretion. MUC5B is required for airway defense. However, the research on the role of MUC5B in airway inflammation induced by atmospheric PM_2.5 remains limited. This study was designed to explore the role of MUC5B in airway inflammation induced by atmospheric PM_2.5. In vivo, Wistar rats were exposed to 0, 1.5, 7.5, 37.5 mg/ kg PM_2.5 saline suspension via intratracheal instillation. HE staining and AB-PAS staining were used to observe the airway inflammation and goblet cell hyperplasia. In vitro, normal A549 cells and MUC5B-knockdown A549 cells were exposed to 0, 100, 200 and 400 μg/mL PM_2.5 for 6 h, 12 h, 24 h and 48 h. ELISA was used to measure the levels of TNF-α and IL-1β in serum and bronchoalveolar lavage fluid of rats and in cell culture. Real time-PCR and ELISA were used to quantify the mRNA and protein levels of MUC5B in trachea and lung of rats and in A549 cells. PM_2.5 could cause the infiltration of inflammatory cells and increase the mucus secretions and goblet cell metaplasia. MUC5B is related to rats' airway inflammation induced by PM_2.5. A549 cells exposed to PM_2.5 in higher concentration and longer time, the protein level of MUC5B was significantly increased, while the levels of IL-1β, TNF-α and MUC5B mRNA were significantly decreased. Compared with normal A549 cells, the levels of IL-1β and TNF-α were significantly higher in Muc5b-knockdown cells. Atmospheric PM_2.5 can induce airway inflammation and mucin secretion. MUC5B played a critical role in controlling the inflammatory response induced by PM_2.5.

Risk of Cardiovascular Hospital Admission After Exposure to Fine Particulate Pollution

BACKGROUND

Heavy fine particulate matter with an aerodynamic diameter ≤2.5 μm (PM_2.5) pollution events continue to occur frequently in developing countries.

OBJECTIVES

The authors conducted a case-crossover study aimed at exploring the association between heavy PM_2.5 pollution events and hospital admission for cardiovascular diseases.

METHODS

Hospital admissions for cardiovascular diseases were observed by Beijing Municipal Commission of Health and Family Planning Information Center from 2013 to 2017. Air pollution data were collected from the Beijing Municipal Environmental Monitoring Center. Distinct definitions were used to identify heavy and extremely heavy fine particulate pollution events. A conditional logistic regression model was used. The hospital admission burdens for cardiovascular disease were also estimated.

RESULTS

A total of 2,202,244 hospital admissions for cardiovascular diseases and 222 days of extremely heavy PM_2.5 pollution events (PM_2.5 concentration ≥150 μg/m³) were observed. The ORs associated with extremely heavy PM_2.5 pollution events lasting for 3 days or more for total cardiovascular disease, angina, myocardial infarction, ischemic stroke, and heart failure were 1.085 (95% CI: 1.077-1.093), 1.112 (95% CI: 1.095-1.130), 1.068 (95% CI: 1.037-1.100), 1.071 (95% CI: 1.053-1.090), and 1.060 (95% CI: 1.021-1.101), respectively. The numbers and days of cardiovascular disease hospital admission annually related to extremely heavy PM_2.5 pollution events lasting for 1 day or more were 3,311 (95% CI: 2,969-3,655) and 37,020 (95% CI: 33,196-40,866), respectively.

CONCLUSIONS

Heavy and extremely heavy PM_2.5 pollution events resulted in substantial increased hospital admission risk for cardiovascular disease. With higher PM_2.5 concentration and longer duration of heavy PM_2.5 pollution events, a greater risk of cardiovascular hospital admission was observed.

Associations of ultrafine and fine particles with childhood emergency room visits for respiratory diseases in a megacity

BACKGROUND

Ambient fine particulate matter with aerodynamic diameter less than 2.5 µm (PM_2.5) has been associated with deteriorated respiratory health, but evidence on particles in smaller sizes and childhood respiratory health has been limited.

METHODS

We collected time-series data on daily respiratory emergency room visits (ERVs) among children under 14 years old in Beijing, China, during 2015-2017. Concurrently, size-fractioned number concentrations of particles in size ranges of 5-560 nm (PNC_5-560) and mass concentrations of PM_2.5, black carbon (BC) and nitrogen dioxide (NO₂) were measured from a fixed-location monitoring station in the urban area of Beijing. Confounder-adjusted Poisson regression models were used to estimate excessive risks (ERs) of particle size fractions on childhood respiratory ERVs, and positive matrix factorisation models were applied to apportion the sources of PNC_5-560.

RESULTS

Among the 136 925 cases of all-respiratory ERVs, increased risks were associated with IQR increases in PNC_25-100 (ER=5.4%, 95% CI 2.4% to 8.6%), PNC_100-560 (4.9%, 95% CI 2.5% to 7.3%) and PM_2.5 (1.3%, 95% CI 0.1% to 2.5%) at current and 1 prior days (lag0-1). Major sources of PNC_5-560 were identified, including nucleation (36.5%), gasoline vehicle emissions (27.9%), diesel vehicle emissions (18.9%) and secondary aerosols (10.6%). Emissions from gasoline and diesel vehicles were found of significant associations with all-respiratory ERVs, with increased ERs of 6.0% (95% CI 2.5% to 9.7%) and 4.4% (95% CI 1.7% to 7.1%) at lag0-1 days, respectively. Exposures to other traffic-related pollutants (BC and NO₂) were also associated with increased respiratory ERVs.

CONCLUSION

Our findings suggest that exposures to higher levels of PNC_5-560 from traffic emissions could be attributed to increased childhood respiratory morbidity, which supports traffic emission control priority in urban areas.

Effect of ambient fine particulates (PM2.5) on hospital admissions for respiratory and cardiovascular diseases in Wuhan, China

Background

Positive associations between ambient PM_2.5 and cardiorespiratory disease have been well demonstrated during the past decade. However, few studies have examined the adverse effects of PM_2.5 based on an entire population of a megalopolis. In addition, most studies in China have used averaged data, which results in variations between monitoring and personal exposure values, creating an inherent and unavoidable type of measurement error.

Methods

This study was conducted in Wuhan, a megacity in central China with about 10.9 million people. Daily hospital admission records, from October 2016 to December 2018, were obtained from the Wuhan Information center of Health and Family Planning, which administrates all hospitals in Wuhan. Daily air pollution concentrations and weather variables in Wuhan during the study period were collected. We developed a land use regression model (LUR) to assess individual PM_2.5 exposure. Time-stratified case-crossover design and conditional logistic regression models were adopted to estimate cardiorespiratory hospitalization risks associated with short-term exposure to PM_2.5. We also conducted stratification analyses by age, sex, and season.

Results

A total of 2,806,115 hospital admissions records were collected during the study period, from which we identified 332,090 cardiovascular disease admissions and 159,365 respiratory disease admissions. Short-term exposure to PM_2.5 was associated with an increased risk of a cardiorespiratory hospital admission. A 10 μg/m³ increase in PM_2.5 (lag0–2 days) was associated with an increase in hospital admissions of 1.23% (95% CI 1.01–1.45%) and 1.95% (95% CI 1.63–2.27%) for cardiovascular and respiratory diseases, respectively. The elderly were at higher PM-induced risk. The associations appeared to be more evident in the cold season than in the warm season.

Conclusions

This study contributes evidence of short-term effects of PM_2.5 on cardiorespiratory hospital admissions, which may be helpful for air pollution control and disease prevention in Wuhan.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-021-01731-x.

Cardiovascular morbidity and mortality associations with biomass- and fossil-fuel-combustion fine-particulate-matter exposures in Dhaka, Bangladesh

BACKGROUND

Fine-particulate-matter (i.e. with an aerodynamic diameter of ≤2.5 µm, PM2.5) air pollution is commonly treated as if it had 'equivalent toxicity', irrespective of the source and composition. We investigate the respective roles of fossil-fuel- and biomass-combustion particles in the PM2.5 relationship with cardiovascular morbidity and mortality using tracers of sources in Dhaka, Bangladesh. Results provide insight into the often observed levelling of the PM2.5 exposure-response curve at high-pollution levels.

METHODS

A time-series regression model, adjusted for potentially confounding influences, was applied to 340 758 cardiovascular disease (CVD) emergency-department visits (EDVs) during January 2014 to December 2017, 253 407 hospital admissions during September 2013 to December 2017 and 16 858 CVD deaths during January 2014 to October 2017.

RESULTS

Significant associations were confirmed between PM2.5-mass exposures and increased risk of cardiovascular EDV [0.27%, (0.07% to 0.47%)] at lag-0, hospitalizations [0.32% (0.08% to 0.55%)] at lag-0 and deaths [0.87%, (0.27% to 1.47%)] at lag-1 per 10-μg/m3 increase in PM2.5. However, the relationship of PM2.5 with morbidity and mortality effect slopes was less steep and non-significant at higher PM2.5 concentrations (during crop-burning-dominated exposures) and varied with PM2.5 source. Fossil-fuel-combustion PM2.5 had roughly a four times greater effect on CVD mortality and double the effect on CVD hospital admissions on a per-µg/m3 basis than did biomass-combustion PM2.5.

CONCLUSION

Biomass burning was responsible for most PM2.5 air pollution in Dhaka, but fossil-fuel-combustion PM2.5 dominated the CVD adverse health impacts. Such by-source variations in the health impacts of PM2.5 should be considered in conducting ambient particulate-matter risk assessments, as well as in prioritizing air-pollution-mitigation measures and clinical advice.

Short-Term Effects of Air Pollution on Cardiovascular Hospitalizations in the Pisan Longitudinal Study

Air pollution effects on cardiovascular hospitalizations in small urban/suburban areas have been scantly investigated. Such effects were assessed among the participants in the analytical epidemiological survey carried out in Pisa and Cascina, Tuscany, Italy (2009–2011). Cardiovascular hospitalizations from 1585 subjects were followed up (2011–2015). Daily mean pollutant concentrations were estimated through random forests at 1 km (particulate matter: PM₁₀, 2011–2015; PM_2.5, 2013–2015) and 200 m (PM₁₀, PM_2.5, NO₂, O₃, 2013–2015) resolutions. Exposure effects were estimated using the case-crossover design and conditional logistic regression (odds ratio—OR—and 95% confidence interval—CI—for 10 μg/m³ increase; lag 0–6). During the period 2011–2015 (137 hospitalizations), a significant effect at lag 0 was observed for PM₁₀ (OR = 1.137, CI: 1.023–1.264) at 1 km resolution. During the period 2013–2015 (69 hospitalizations), significant effects at lag 0 were observed for PM₁₀ (OR = 1.268, CI: 1.085–1.483) and PM_2.5 (OR = 1.273, CI: 1.053–1.540) at 1 km resolution, as well as for PM₁₀ (OR = 1.365, CI: 1.103–1.690), PM_2.5 (OR = 1.264, CI: 1.006–1.589) and NO₂ (OR = 1.477, CI: 1.058–2.061) at 200 m resolution; significant effects were observed up to lag 2. Larger ORs were observed in males and in subjects reporting pre-existent cardiovascular/respiratory diseases. Combining analytical and routine epidemiological data with high-resolution pollutant estimates provides new insights on acute cardiovascular effects in the general population and in potentially susceptible subgroups living in small urban/suburban areas.

Meta-analysis on short-term exposure to ambient ultrafine particles and respiratory morbidity

Aim

There is growing interest in the health effects following exposure to ambient particles with a diameter <100 nm defined as ultrafine particles (UFPs), although studies so far have reported inconsistent results. We have undertaken a systematic review and meta-analysis for respiratory hospital admissions and emergency room visits following short-term exposure to UFPs.

Methods

We searched PubMed and the Web of Science for studies published up to March 2019 to update previous reviews. We applied fixed- and random-effects models, assessed heterogeneity between cities and explored possible effect modifiers.

Results

We identified nine publications, reporting effects from 15 cities, 11 of which were European. There was great variability in exposure assessment, outcome measures and the exposure lags considered. Our meta-analyses did not support UFP effects on respiratory morbidity across all ages. We found consistent statistically significant associations following lag 2 exposure during the warm period and in cities with mean daily UFP concentrations <6000 particles·cm^‒3, which was approximately the median of the city-specific mean levels. Among children aged 0–14 years, a 10 000 particle·cm^‒3 increase in UFPs 2 or 3 days before was associated with a relative risk of 1.01 (95% CI 1.00–1.02) in respiratory hospital admissions.

Conclusions

Our study indicates UFP effects on respiratory health among children, and during the warm season across all ages at longer lags. The limited evidence and the large heterogeneity of previous reports call for future exposure assessment harmonisation and expanded research.

Studies on short-term exposure to ultrafine particles and respiratory admissions show large variability in the exposure assessment methodology. We found indications of effects in lower concentrations, children and during the warm period of the year.https://bit.ly/2zynMza

Ambient air pollution and cause-specific risk of hospital admission in China: A nationwide time-series study

BACKGROUND

The impacts of air pollution on circulatory and respiratory systems have been extensively studied. However, the associations between air pollution exposure and the risk of noncommunicable diseases of other organ systems, including diseases of the digestive, musculoskeletal, and genitourinary systems, remain unclear or inconclusive. We aimed to systematically assess the associations between short-term exposure to main air pollutants (fine particulate matter [PM2.5] and ozone) and cause-specific risk of hospital admission in China over a wide spectrum of human diseases.

METHODS AND FINDINGS

Daily data on hospital admissions for primary diagnosis of 14 major and 188 minor disease categories in 252 Chinese cities (107 cities in North China and 145 cities in South China) from January 1, 2013, to December 31, 2017, were obtained from the Hospital Quality Monitoring System of China (covering 387 hospitals in North China and 614 hospitals in South China). We applied a 2-stage analytic approach to assess the associations between air pollution and daily hospital admissions. City-specific associations were estimated with quasi-Poisson regression models and then pooled by random-effects meta-analyses. Each disease category was analyzed separately, and the P values were adjusted for multiple comparisons. A total of 117,338,867 hospital admissions were recorded in the study period. Overall, 51.7% of the hospitalized cases were male, and 71.3% were aged <65 years. Robust positive associations were found between short-term PM2.5 exposure and hospital admissions for 7 major disease categories: (1) endocrine, nutritional, and metabolic diseases; (2) nervous diseases; (3) circulatory diseases; (4) respiratory diseases; (5) digestive diseases; (6) musculoskeletal and connective tissue diseases; and (7) genitourinary diseases. For example, a 10-μg/m3 increase in PM2.5 was associated with a 0.21% (95% CI 0.15% to 0.27%; adjusted P < 0.001) increase in hospital admissions for diseases of the digestive system on the same day in 2-pollutant models (adjusting for ozone). There were 35 minor disease categories significantly positively associated with same-day PM2.5 in both single- and 2-pollutant models, including diabetes mellitus, anemia, intestinal infection, liver diseases, gastrointestinal hemorrhage, renal failure, urinary tract calculus, chronic ulcer of skin, and back problems. The association between short-term ozone exposure and respiratory diseases was robust. No safety threshold in the exposure-response relationships between PM2.5 and hospital admissions was observed. The main limitations of the present study included the unavailability of data on personal air pollution exposures.

CONCLUSIONS

In the Chinese population during 2013-2017, short-term exposure to air pollution, especially PM2.5, was associated with increased risk of hospitalization for diseases of multiple organ systems, including certain diseases of the digestive, musculoskeletal, and genitourinary systems; many of these associations are important but still not fully recognized. The effect estimates and exposure-response relationships can inform policy making aimed at protecting public health from air pollution in China.

Effects of Ultrafine Particles in Ambient Air on Primary Health Care Consultations for Diabetes in Children and Elderly Population in Ljubljana, Slovenia: A 5-Year Time-Trend Study

Epidemiological studies indicate that exposure to ultrafine particles (UFP) in ambient air represents an important environmental public health issue. The aim of this study was to determine the association between UFP in ambient air and the daily number of consultations in the primary health care unit due to diabetes mellitus in children and elderly population of the Municipality of Ljubljana. A 5-year time-trend ecological study was carried out for the period between 1 January 2013 and 31 December 2017. The daily number of primary health care consultations due to diabetes mellitus among children and elderly population was observed as the health outcome. Daily mean UFP concentrations (different size from 10 to 100 nm) were measured and calculated. Poisson regression analysis was used to investigate the association between the observed outcome and the daily UFP, particulate matter fine fraction (PM_2.5), and particulate matter coarse fraction (PM₁₀) concentrations, adjusted to other covariates. The results show that the daily number of consultations due to diabetes mellitus were highly significantly associated with the daily concentrations of UFP (10 to 20 nm; p ≤ 0.001 and 20 to 30 nm; p ≤ 0.001) in all age groups and in the elderly population. In observed the population of children, we did not confirm the association. Findings indicate that specified environmental challenges should be addressed by comprehensive public health strategies leading to the coordinated cross-sectoral measures for the reduction of UFP in ambient air and the mitigation of adverse health effects.

Temperature modulation of the adverse consequences on human mortality due to exposure to fine particulates: A study of multiple cities in China

Exposure to particulate matter of smaller than 2.5 μm in diameter (PM_2.5) is linked to increased human mortality, and could be further complicated by concurrent ambient air temperatures. Published reports indicate that the association between ambient temperatures and mortality due to PM_2.5 exposure is dissimilar across different geographic areas. Thus, it is unclear how ambient temperatures at different geographic locations can together modulate the influence of PM_2.5 on mortality. In this paper, we examined how temperature modulated the association between mortality and PM_2.5 exposure in 15 Chinese cities during 2014-2016. For analysis, First, Poisson generalized additive models under different temperature stratifications (<10th, 10-90th, and >90th temperature percentiles) was used to estimate PM_2.5 associations to mortality, which were specific to different cities. Second, we used a meta-analysis to combine the effects at each temperature stratum and region (southern and northern China). Results revealed that high temperatures (daily mean temperature >90th percentile) robustly amplified observed associations of mortality and PM_2.5 exposure, and the modifications were heterogeneous geographically. In the northern regions, a 10 μg/m³ increment in PM_2.5 was associated with 0.18%, 0.28%, and 1.54% increase in non-accidental mortalities and 0.33%, 0.39%, and 1.32% increase in cardiovascular mortalities at low, moderate, and high temperature levels, respectively. In the southern regions, a 10 μg/m³ increment in PM_2.5 was associated with 0.52%, 0.62%, and 1.90% increase in non-accidental mortalities and 0.55%, 0.98%, and 2.25% increase in cardiovascular mortalities at low, moderate, and high temperature levels, respectively. It is concluded that temperature altered PM_2.5-mortality associations in southern and northern China synergistically, but the effect was more pronounced in the south. Therefore, geography and temperature need to be considered when studying how PM_2.5 affects health.

Fine particulate air pollution and adult hospital admissions in 200 Chinese cities: a time-series analysis

BACKGROUND

The association between short-term exposure to ambient fine particulate matter (PM2.5) and morbidity risk in developing countries is not fully understood. We conducted a nationwide time-series study to estimate the short-term effect of PM2.5 on hospital admissions in Chinese adults.

METHODS

Daily counts of hospital admissions for 2014-16 were obtained from the National Urban Employee Basic Medical Insurance database. We identified more than 58 million hospitalizations from 0.28 billion insured persons in 200 Chinese cities for subjects aged 18 years or older. Generalized additive models with quasi-Poisson regression were applied to examine city-specific associations of PM2.5 concentrations with hospital admissions. National-average estimates of the association were obtained from a random-effects meta-analysis. We also investigated potential effect modifiers, such as age, sex, temperature and relative humidity.

RESULTS

An increase of 10 μg/m3 in same-day PM2.5 concentrations was positively associated with a 0.19% (95% confidence interval: 0.07-0.30) increase in the daily number of hospital admissions at the national level. PM2.5 exposure remained positively associated with hospital admissions on days when the daily concentrations met the current Chinese Ambient Air Quality Standards (75 μg/m3). Estimates of admission varied across cities and increased in cities with lower PM2.5 concentrations (p = 0.044) or higher temperatures (p = 0.002) and relative humidity (p = 0.003). The elderly were more sensitive to PM2.5 exposure (p < 0.001).

CONCLUSIONS

Short-term exposure to PM2.5 was positively associated with adult hospital admissions in China, even at levels below current Chinese Ambient Air Quality Standards.

Association between ambient fine particulate pollution and hospital admissions for cause specific cardiovascular disease: time series study in 184 major Chinese cities

OBJECTIVE

To estimate the risks of daily hospital admissions for cause specific major cardiovascular diseases associated with short term exposure to ambient fine particulate matter (aerodynamic diameter ≤2.5 μm; PM_2.5) pollution in China.

DESIGN

National time series study.

SETTING

184 major cities in China.

POPULATION

8 834 533 hospital admissions for cardiovascular causes in 184 Chinese cities recorded by the national database of Urban Employee Basic Medical Insurance from 1 January 2014 to 31 December 2017.

MAIN OUTCOME MEASURES

Daily counts of city specific hospital admissions for primary diagnoses of ischaemic heart disease, heart failure, heart rhythm disturbances, ischaemic stroke, and haemorrhagic stroke among different demographic groups were used to estimate the associations between PM_2.5 and morbidity. An overdispersed generalised additive model was used to estimate city specific associations between PM_2.5 and cardiovascular admissions, and random effects meta-analysis used to combine the city specific estimates.

RESULTS

Over the study period, a mean of 47 hospital admissions per day (standard deviation 74) occurred for cardiovascular disease, 26 (53) for ischaemic heart disease, one (five) for heart failure, two (four) for heart rhythm disturbances, 14 (28) for ischaemic stroke, and two (four) for haemorrhagic stroke. At the national average level, an increase of 10 μg/m³ in PM_2.5 was associated with a 0.26% (95% confidence interval 0.17% to 0.35%) increase in hospital admissions on the same day for cardiovascular disease, 0.31% (0.22% to 0.40%) for ischaemic heart disease, 0.27% (0.04% to 0.51%) for heart failure, 0.29% (0.12% to 0.46%) for heart rhythm disturbances, and 0.29% (0.18% to 0.40%) for ischaemic stroke, but not with haemorrhagic stroke (-0.02% (-0.23% to 0.19%)). The national average association of PM_2.5 with cardiovascular disease was slightly non-linear, with a sharp slope at PM_2.5 levels below 50 μg/m³, a moderate slope at 50-250 μg/m³, and a plateau at concentrations higher than 250 μg/m³. Compared with days with PM_2.5 up to 15 μg/m³, days with PM_2.5 of 15-25, 25-35, 35-75, and 75 μg/m³ or more were significantly associated with increases in cardiovascular admissions of 1.1% (0 to 2.2%), 1.9% (0.6% to 3.2%), 2.6% (1.3% to 3.9%), and 3.8% (2.1% to 5.5%), respectively.According to projections, achieving the Chinese grade 2 (35 μg/m³), Chinese grade 1 (15 μg/m³), and World Health Organization (10 μg/m³) regulatory limits for annual mean PM_2.5 concentrations would reduce the annual number of admissions for cardiovascular disease in China. Assuming causality, which should be done with caution, this reduction would translate into an estimated 36 448 (95% confidence interval 24 441 to 48 471), 85 270 (57 129 to 113 494), and 97 516 (65 320 to 129 820), respectively.

CONCLUSIONS

These data suggest that in China, short term exposure to PM_2.5 is associated with increased hospital admissions for all major cardiovascular diseases except for haemorrhagic stroke, even for exposure levels not exceeding the current regulatory limits.

Ultrafine particles and PM2.5 in the air of cities around the world: Are they representative of each other?

Can mitigating only particle mass, as the existing air quality measures do, ultimately lead to reduction in ultrafine particles (UFP)? The aim of this study was to provide a broader urban perspective on the relationship between UFP, measured in terms of particle number concentration (PNC) and PM_2.5 (mass concentration of particles with aerodynamic diameter < 2.5 μm) and factors that influence their concentrations. Hourly average PNC and PM_2.5 were acquired from 10 cities located in North America, Europe, Asia, and Australia over a 12-month period. A pairwise comparison of the mean difference and the Kolmogorov-Smirnov test with the application of bootstrapping were performed for each city. Diurnal and seasonal trends were obtained using a generalized additive model (GAM). The particle number to mass concentration ratios and the Pearson's correlation coefficient were calculated to elucidate the nature of the relationship between these two metrics. Results show that the annual mean concentrations ranged from 8.0 × 10³ to 19.5 × 10³ particles·cm^-3 and from 7.0 to 65.8 μg·m^-3 for PNC and PM_2.5, respectively, with the data distributions generally skewed to the right, and with a wider spread for PNC. PNC showed a more distinct diurnal trend compared with PM_2.5, attributed to the high contributions of UFP from vehicular emissions to PNC. The variation in both PNC and PM_2.5 due to seasonality is linked to the cities' geographical location and features. Clustering the cities based on annual median concentrations of both PNC and PM_2.5 demonstrated that a high PNC level does not lead to a high PM_2.5, and vice versa. The particle number-to-mass ratio (in units of 10⁹ particles·μg^-1) ranged from 0.14 to 2.2, >1 for roadside sites and <1 for urban background sites with lower values for more polluted cities. The Pearson's r ranged from 0.09 to 0.64 for the log-transformed data, indicating generally poor linear correlation between PNC and PM_2.5. Therefore, PNC and PM_2.5 measurements are not representative of each other; and regulating PM_2.5 does little to reduce PNC. This highlights the need to establish regulatory approaches and control measures to address the impacts of elevated UFP concentrations, especially in urban areas, considering their potential health risks.

Ambient Coarse Particulate Matter and Hospital Admissions for Ischemic Stroke

Background and Purpose—

Evidence on the effects of coarse particulate matter (PM 10–2.5 ) on ischemic stroke is limited and inconsistent. We evaluated the acute effects of PM 10–2.5 exposure on hospital admissions for ischemic stroke in China.

Methods—

We conducted a national time-series analysis of associations between daily PM 10–2.5 concentrations and daily hospital admissions for ischemic stroke in China between January 2014 and December 2016. Hospital admissions for ischemic stroke were identified from the database of Urban Employee Basic Medical Insurance, which contains data from 0.28 billion beneficiaries. We applied a city-specific Poisson regression to examine the associations of PM 10–2.5 and daily ischemic stroke admissions. We combined the city-specific effect estimates with a random effects meta-analysis, and further evaluated the exposure-response relationship curve and potential effect modifiers.

Results—

We identified >2 million hospital admissions for ischemic stroke in 172 Chinese cities. A 10 μg/m 3 increase in PM 10–2.5 concentrations (lag day 0) was associated with a 0.91% (95% CI, 0.73–1.10) increase in hospital admissions for ischemic stroke. The association remained significant after adjusting for PM 2.5 (percentage change, 0.96%; 95% CI, 0.75–1.18). The exposure-response relationship was approximately linear, with a moderate response at lower levels (<200 μg/m 3 ) and a steeper response at higher levels. The association was stronger in cities with lower PM 10–2.5 concentrations, higher temperatures, or higher relative humidity.

Conclusions—

This nationwide study provides robust evidence of the short-term association between exposure to PM 10–2.5 and increased hospital admissions for ischemic stroke and supports the hypothesis that the association differs by city characteristics.

Association of ambient air pollution with lengths of hospital stay for hanoi children with acute lower-respiratory infection, 2007-2016

INTRODUCTION

The association between ambient air pollution and length of hospital stay (LOS) for children with lower-respiratory infection is unclear.

MATERIALS AND METHODS

The association was examined using admission data for 75,432 children in Hanoi, aged 0-5 years, hospitalized with acute lower-respiratory infection (ALRI) and daily air pollutant levels in Hanoi between 2007 and 2016. We estimated the odds ratio of being discharged for an interquartile range (IQR) increment (IQR) of ambient pollutants during one to four days prior to admission date. We used pooled logistic regression models including a B-spline function of calendar time and terms describing the baseline odds, adjusting for meteorological factors, age, gender, residential location, week-day of admission, discharge on weekends or holidays, and number of respiratory hospitalizations one day prior to the discharge date.

RESULTS

An IQR increase in O₃ concentrations (85.8 μg/m³) was associated with a 5% (95%CI: 2%-8%) decrease in the odds of discharge from hospital among children with ALRI. Results were similar for PM₁₀, but only for children aged 2-5 years. For the other pollutants, corresponding associations were close to null or in the opposite direction. For example, increase in CO was associated with shorter LOS.

CONCLUSIONS

Our study provides the first investigation of the associations between lengths of hospital stays and air pollutant levels prior to hospitalization in Asian children. Increased levels of O₃ prior to admission predicted prolonged hospitalizations. The inconsistencies in the findings for other pollutants call for further investigations.

Long-Term Exposure to Ultrafine Particles and Incidence of Cardiovascular and Cerebrovascular Disease in a Prospective Study of a Dutch Cohort

BACKGROUND

There is growing evidence that exposure to ultrafine particles (UFP; particles smaller than [Formula: see text]) may play an underexplored role in the etiology of several illnesses, including cardiovascular disease (CVD).

OBJECTIVES

We aimed o investigate the relationship between long-term exposure to ambient UFP and incident cardiovascular and cerebrovascular disease (CVA). As a secondary objective, we sought to compare effect estimates for UFP with those derived for other air pollutants, including estimates from two-pollutant models.

METHODS

Using a prospective cohort of 33,831 Dutch residents, we studied the association between long-term exposure to UFP (predicted via land use regression) and incident disease using Cox proportional hazard models. Hazard ratios (HR) for UFP were compared to HRs for more routinely monitored air pollutants, including particulate matter with aerodynamic diameter [Formula: see text] ([Formula: see text]), PM with aerodynamic diameter [Formula: see text] ([Formula: see text]), and [Formula: see text].

RESULTS

Long-term UFP exposure was associated with an increased risk for all incident CVD [[Formula: see text] per [Formula: see text]; 95% confidence interval (CI): 1.03, 1.34], myocardial infarction (MI) ([Formula: see text]; 95% CI: 1.00, 1.79), and heart failure ([Formula: see text]; 95% CI: 1.17, 2.66). Positive associations were also estimated for [Formula: see text] ([Formula: see text]; 95% CI: 1.01, 1.48 per [Formula: see text]) and coarse PM ([Formula: see text]; HR for all [Formula: see text]; 95% CI: 1.01, 1.45 per [Formula: see text]). CVD was not positively associated with [Formula: see text] (HR for all [Formula: see text]; 95% CI: 0.75, 1.28 per [Formula: see text]). HRs for UFP and CVAs were positive, but not significant. In two-pollutant models ([Formula: see text] and [Formula: see text]), positive associations tended to remain for UFP, while HRs for [Formula: see text] and [Formula: see text] generally attenuated towards the null.

CONCLUSIONS

These findings strengthen the evidence that UFP exposure plays an important role in cardiovascular health and that risks of ambient air pollution may have been underestimated based on conventional air pollution metrics. https://doi.org/10.1289/EHP3047.

Association between ambient air pollution and daily hospital admissions for ischemic stroke: A nationwide time-series analysis

BACKGROUND

Evidence of the short-term effects of ambient air pollution on the risk of ischemic stroke in low- and middle-income countries is limited and inconsistent. We aimed to examine the associations between air pollution and daily hospital admissions for ischemic stroke in China.

METHODS AND FINDINGS

We identified hospital admissions for ischemic stroke in 2014-2016 from the national database covering up to 0.28 billion people who received Urban Employee Basic Medical Insurance (UEBMI) in China. We examined the associations between air pollution and daily ischemic stroke admission using a two-stage method. Poisson time-series regression models were firstly fitted to estimate the effects of air pollution in each city. Random-effects meta-analyses were then conducted to combine the estimates. Meta-regression models were applied to explore potential effect modifiers. More than 2 million hospital admissions for ischemic stroke were identified in 172 cities in China. In single-pollutant models, increases of 10 μg/m3 in particulate matter with aerodynamic diameter <2.5 μm (PM2.5), sulfur dioxide (SO2), nitrogen dioxide (NO2), and ozone (O3) and 1 mg/m3 in carbon monoxide (CO) concentrations were associated with 0.34% (95% confidence interval [CI], 0.20%-0.48%), 1.37% (1.05%-1.70%), 1.82% (1.45%-2.19%), 0.01% (-0.14%-0.16%), and 3.24% (2.05%-4.43%) increases in hospital admissions for ischemic stroke on the same day, respectively. SO2 and NO2 associations remained significant in two-pollutant models, but not PM2.5 and CO associations. The effect estimates were greater in cities with lower air pollutant levels and higher air temperatures, as well as in elderly subgroups. The main limitation of the present study was the unavailability of data on individual exposure to ambient air pollution.

CONCLUSIONS

As the first national study in China to systematically examine the associations between short-term exposure to ambient air pollution and ischemic stroke, our findings indicate that transient increase in air pollution levels may increase the risk of ischemic stroke, which may have significant public health implications for the reduction of ischemic stroke burden in China.

Association of ultrafine particles with cardiopulmonary health among adult subjects in the urban areas of northern Taiwan

The association between short-term exposure to particulate air pollution, especially fine particles, and cardiopulmonary health has been well-established in previous studies. However, previous findings regarding the effect of ultrafine particles (UFPs) on cardiopulmonary health are inconsistent. We repeatedly measured the mass concentrations of UFPs using a Micro-Orifice Uniform Deposit Impactor (MOUDI) in the apartments of 100 adult participants and collected the participants' health data from the pulmonary outpatient unit of Shuang-Ho Hospital to investigate the association between short-term exposure to UFPs and cardiopulmonary health using mixed-effects models from January 1, 2014 to August 31, 2017. We also collected ambient air pollution monitoring data from the Taiwan Environmental Protection Administration for data analysis. We observed that an interquartile range increase in the 24-hour mean UFPs (0.97 μg/m³) was associated with a 6.3% [95% confidence interval (CI) = 2.9, 9.7], 5.6% (95% CI = 4.1, 7.1) and 8.5% (95% CI = 3.9, 13.1) increase in systolic blood pressure, diastolic blood pressure and high sensitivity-C-reactive protein, respectively. We also observed the association of particulate matter less than or equal to 2.5 μm in diameter and nitrogen dioxide with increased blood pressure and ozone with decreased lung function. A negative trend between UFPs and forced expiratory volume in the first second was observed. We concluded that short-term exposure to UFPs was associated with cardiovascular health in adult subjects in the urban areas of northern Taiwan.

Ultrafine Particulate Matter Combined With Ozone Exacerbates Lung Injury in Mature Adult Rats With Cardiovascular Disease

Particulate matter (PM) and ozone (O3) are dominant air pollutants that contribute to development and exacerbation of multiple cardiopulmonary diseases. Mature adults with cardiovascular disease (CVD) are particularly susceptible to air pollution-related cardiopulmonary morbidities and mortalities. The aim was to investigate the biologic potency of ultrafine particulate matter (UFPM) combined with O3 in the lungs of mature adult normotensive and spontaneously hypertensive (SH) Wistar-Kyoto rats. Conscious, mature adult male normal Wistar-Kyoto (NW) and SH rats were exposed to one of the following atmospheres: filtered air (FA); UFPM (∼ 250 μg/m3); O3 (1.0 ppm); or UFPM + O3 (∼ 250 μg/m3 + 1.0 ppm) combined for 6 h, followed by an 8 h FA recovery period. Lung sections were evaluated for lesions in the large airways, terminal bronchiolar/alveolar duct regions, alveolar parenchyma, and vasculature. NW and SH rats were similarly affected by the combined-pollutant exposure, displaying severe injury in both large and small airways. SH rats were particularly susceptible to O3 exposure, exhibiting increased injury scores in terminal bronchioles and epithelial degeneration in large airways. UFPM-exposure groups had minimal histologic changes. The chemical composition of UFPM was altered by the addition of O3, indicating that ozonolysis promoted compound degradation. O3 increased the biologic potency of UFPM, resulting in greater lung injury following exposure. Pathologic manifestations of CVD may confer susceptibility to air pollution by impairing normal lung defenses and responses to exposure.

Acute effects of ambient air pollution on lower respiratory infections in Hanoi children: An eight-year time series study

BACKGROUND

Lower respiratory diseases are the most frequent causes of hospital admission in children worldwide, particularly in developing countries. Daily levels of air pollution are associated with lower respiratory diseases, as documented in many time-series studies. However, investigations in low-and-middle-income countries, such as Vietnam, remain sparse.

OBJECTIVE

This study investigated the short-term association of ambient air pollution with daily counts of hospital admissions due to pneumonia, bronchitis and asthma among children aged 0-17 in Hanoi, Vietnam. We explored the impact of age, gender and season on these associations.

METHODS

Daily ambient air pollution concentrations and hospital admission counts were extracted from electronic databases received from authorities in Hanoi for the years 2007-2014. The associations between outdoor air pollution levels and hospital admissions were estimated for time lags of zero up to seven days using Quasi-Poisson regression models, adjusted for seasonal variations, meteorological variables, holidays, influenza epidemics and day of week.

RESULTS

All ambient air pollutants were positively associated with pneumonia hospitalizations. Significant associations were found for most pollutants except for ozone and sulfur dioxide in children aged 0-17. Increments of an interquartile range (21.9μg/m³) in the 7-day-average level of NO₂ were associated with a 6.1% (95%CI 2.5% to 9.8%) increase in pneumonia hospitalizations. These associations remained stable in two-pollutant models. All pollutants other than CO were positively associated with hospitalizations for bronchitis and asthma. Associations were weaker in infants than in children aged 1-5.

CONCLUSION

Strong associations between hospital admissions for lower respiratory infections and daily levels of air pollution confirm the need to adopt sustainable clean air policies in Vietnam to protect children's health.

Ultrafine particulate matter exposure impairs vasorelaxant response in superoxide dismutase 2-deficient murine aortic rings

Studies have linked exposure to ultrafine particulate matter (PM) and adverse cardiovascular events. PM-induced oxidative stress is believed to be a key mechanism underlying observed adverse vascular effects. Advanced age is one factor known to decrease antioxidant defenses and confer susceptibility to the detrimental vascular effects seen following PM exposure. The present study was designed to investigate the vasomotor responses following ultrafine PM exposure in wild type (WT) and superoxide dismutase 2-deficient (SOD2+/-) mice that possess decreased antioxidant defense. Thoracic aortic rings isolated from young and aged WT and SOD2+/- mice were exposed to ultrafine PM in a tissue bath system. Aortic rings were then constricted with increasing concentrations of phenylephrine, followed by relaxation with rising amounts of nitroglycerin (NTG). Data demonstrated that ultrafine PM decreased the relaxation response in both young WT and young SOD2+/- mouse aortas, and relaxation was significantly reduced in young SOD2+/- compared to WT mice. Ultrafine PM significantly diminished the NTG-induced relaxation response in aged compared to young mouse aortas. After ultrafine PM exposure, the relaxation response did not differ markedly between aged WT and aged SOD2+/- mice. Data demonstrated that the greater vascular effect in aortic rings in aged mice ex vivo after ultrafine PM exposure may be attributed to ultrafine PM-induced oxidative stress and loss of antioxidant defenses in aged vascular tissue. Consistent with this conclusion is the attenuation of NTG-induced relaxation response in young SOD2+/- mice.

ABBREVIATIONS

H2O2: hydrogen peroxide; NTG: nitroglycerin; PAH: polycyclic aromatic hydrocarbons; PE: l-phenylephrine; PM: particulate matter; ROS: reactive oxygen species; SOD2: superoxide dismutase 2 deficient; WT: wild type.

Exploratory assessment of indoor and outdoor particle number concentrations in Hanoi households

No studies have been conducted in Vietnam to understand the levels of atmospheric ultrafine particles, despite having adverse health effects. Information about indoor air quality in Vietnam is also limited. Hence we aimed to conduct the first assessment of ultrafine particle concentrations in terms of particle number (PN) in Hanoi, by simultaneously measuring indoor and outdoor PN concentrations from six households at different locations across the city in January 2016. We also acquired PM_2.5 data for this monitoring period from an air quality monitoring station located at the US Embassy in Hanoi, to compare the general trends between PN and PM_2.5 concentrations. The mean daily indoor and outdoor PN concentrations for the monitoring period were 1.9×10⁴p/cm³ and 3.3×10⁴p/cm³, respectively, with an increase during rush hour traffic. It was concluded that traffic was the main contributor to outdoor PN concentrations, with agricultural burning having a small influence at one study location. The mean ratio of indoor to outdoor PN concentrations for all six sites was 0.66±0.26, which points to outdoor air as the main driver of indoor PN concentrations, rather than indoor sources. These PN concentrations and I/O ratios are similar to those reported for a number of cities in developed countries. However, in contrast to PN, ambient mean PM_2.5 concentrations in Hanoi (60-70μg/m³) were significantly higher than those typically recorded in developed countries. These findings demonstrate that urban particle mass (PM_2.5) concentrations are not indicative of the PN concentrations, which can be explained by different sources contributing to PN and PM, and that direct measurements of PN are necessary to provide information about population exposure to ultrafine particles and for management of air quality.

Fine Particulate Air Pollution and Daily Mortality. A Nationwide Analysis in 272 Chinese Cities

RATIONALE

Evidence concerning the acute health effects of air pollution caused by fine particulate matter (PM_2.5) in developing countries is quite limited.

OBJECTIVES

To evaluate short-term associations between PM_2.5 and daily cause-specific mortality in China.

METHODS

A nationwide time-series analysis was performed in 272 representative Chinese cities from 2013 to 2015. Two-stage Bayesian hierarchical models were applied to estimate regional- and national-average associations between PM_2.5 concentrations and daily cause-specific mortality. City-specific effects of PM_2.5 were estimated using the overdispersed generalized additive models after adjusting for time trends, day of the week, and weather conditions. Exposure-response relationship curves and potential effect modifiers were also evaluated.

MEASUREMENTS AND MAIN RESULTS

The average of annual mean PM_2.5 concentration in each city was 56 μg/m³ (minimum, 18 μg/m³; maximum, 127 μg/m³). Each 10-μg/m³ increase in 2-day moving average of PM_2.5 concentrations was significantly associated with increments in mortality of 0.22% from total nonaccidental causes, 0.27% from cardiovascular diseases, 0.39% from hypertension, 0.30% from coronary heart diseases, 0.23% from stroke, 0.29% from respiratory diseases, and 0.38% from chronic obstructive pulmonary disease. There was a leveling off in the exposure-response curves at high concentrations in most, but not all, regions. The associations were stronger in cities with lower PM_2.5 levels or higher temperatures, and in subpopulations with elder age or less education.

CONCLUSIONS

This nationwide investigation provided robust evidence of the associations between short-term exposure to PM_2.5 and increased mortality from various cardiopulmonary diseases in China. The magnitude of associations was lower than those reported in Europe and North America.