Time-stratified Case-crossover Research Articles

Effects of combined exposure to fine particulate matter and cold waves and on IHD hospitalizations at low and high altitudes

Climate change and air pollution are major challenges facing the world today. Cold waves and air pollution significantly impact ischemic heart disease (IHD), but the extent of these effects at different altitudes remains unclear, especially their interactions. We collected daily meteorological, pollutant, and IHD hospitalization data from Xining and Xinxiang from 2016 to 2021. Using a time-stratified case-crossover approach, we fitted conditional Poisson regression models to assess the association between cold waves, PM2.5, and IHD hospitalizations and quantified their interactions. Additionally, we calculated the attributable fraction (AF) and attributable number (AN) of hospitalizations due to exposure to cold waves and medium to high-level PM2.5. We also performed stratified analyses by altitude, gender, and age. Both cold waves and PM2.5 were positively associated with IHD hospitalization rates in Xining and Xinxiang, but the differences between the two regions were not significant. The relative risk of cold waves was 1.15 (1.07, 1.24) in Xining and 1.16 (1.11, 1.21) in Xinxiang. In Xining, there was an interaction between cold waves and different levels of PM2.5. We estimated the attributable fraction due to the joint exposure of cold waves and PM2.5 to be 0.14–0.49 in Xining and 0.26–0.36 in Xinxiang. Older adults and males faced higher risks. This study highlights the importance of reducing PM2.5 exposure and optimizing extreme weather warning systems and suggests further exploration of the impacts of individual behaviors and regional characteristics on IHD.

Maternal Exposure to Ozone and the Risk of Birth Defects: A Time-Stratified Case-Crossover Study in Southwestern China.

A few studies have explored the relationship between air pollution exposure and the risk of birth defects; however, the ozone-related (O3) effects on preconception and first-trimester exposures are still unknown. In this time-stratified case-crossover study, conditional logistic regressions were applied to explore the associations between O3 exposure and the risk of birth defects in Chongqing, China, and stratified analyses were constructed to evaluate the modifiable factors. A total of 6601 cases of birth defects were diagnosed, of which 56.16% were male. O3 exposure was associated with an increased risk of birth defects, and the most significant estimates were observed in the first month before pregnancy: a 10 ug/m3 increase of O3 was related to an elevation of 4.2% [95% confidence interval (CI), 3.4-5.1%]. The associations between O3 exposure and congenital malformations and deformations of the musculoskeletal system were statistically significant during almost all exposure periods. Pregnant women with lower education and income, and from rural areas, were more susceptible to O3 exposure, with the strongest odds ratios (ORs) of 1.066 (95%CI, 1.046-1.087), 1.086 (95%CI, 1.034-1.140), and 1.053 (95%CI, 1.034-1.072), respectively. Our findings highlight the health risks of air pollution exposure and raise awareness of pregnant women's vulnerability and the susceptibility window period.

Association of Psychiatric Emergency Visits and Warm Ambient Temperature during Pregnancy: A Time-Stratified Case-Crossover Study.

Acute exposure to high ambient temperature and heat waves during the warm season has been linked with psychiatric disorders. Emerging research has shown that pregnant people, due to physiological and psychological changes, may be more sensitive to extreme heat, and acute exposure has been linked to increased risk of pregnancy complications; however, few studies have examined psychiatric complications. Our objective was to examine the association between acute exposure to warm ambient temperatures and emergency department (ED) visits for mental disorders during pregnancy. A time-stratified case-crossover design with conditional logistic regression was performed on psychiatric ED visits for pregnant patients in North Carolina, from May to September 2016 to 2019. Daily average ambient temperature was the main exposure and was linked to daily visits by maternal zip code of residence for prenatal mood and anxiety disorders (PMAD), severe mental illness (SMI), mental disorder of pregnancy (MDP), suicidal thoughts (SUIC), and any psychiatric disorder (Any). Effect modification by trimester, residential segregation, economic segregation, urbanicity, and availability of greenspace was also investigated. Each increase in same-day exposure to warm ambient temperature on case days was associated with an increase in incidence rate ratio (IRR) for any psychiatric disorder [IRR = 1.07; 95% confidence interval (CI): 1.01, 1.14] including anxiety (IRR = 1.14; 95% CI: 1.00, 1.30), bipolar disorder (IRR = 1.28; 95% CI: 0.98, 1.67), and suicidal thoughts (IRR = 1.28; 95% CI: 1.00, 1.65) compared to control days. In general, the associations were strongest for warm season temperatures on the same day of exposure or for temperatures averaged over the 3 or 6 d preceding the ED visit. The greatest risk of an incident ED admission for PMAD (RR = 1.20; 95% CI: 1.04, 1.39), particularly for anxiety (RR = 1.30; 95% CI: 1.07, 1.59), and any psychiatric disorder (RR = 1.17; 95% CI: 1.07, 1.28) occurred following cumulative exposure to hot temperatures the week before admission. Higher psychiatric burden from temperature was observed in urban areas and on extreme heat days. For this pregnant population in the southeastern United States, short-term exposure to high ambient temperatures during the warm season was associated with a greater risk of ED visits for an array of psychiatric disorders. Findings show that climate-related increases in ambient temperature may contribute to psychiatric morbidity in pregnant people. https://doi.org/10.1289/EHP13293.

Cold waves and fine particulate matter in high-altitude Chinese cities: assessing their interactive impact on outpatient visits for respiratory disease.

Extreme weather events like heatwaves and fine particulate matter (PM2.5) have a synergistic effect on mortality, but research on the synergistic effect of cold waves and PM2.5 on outpatient visits for respiratory disease, especially at high altitudes in climate change-sensitive areas, is lacking. we collected time-series data on meteorological, air pollution, and outpatient visits for respiratory disease in Xining. We examined the associations between cold waves, PM2.5, and outpatient visits for respiratory disease using a time-stratified case-crossover approach and distributional lag nonlinear modeling. Our analysis also calculated the relative excess odds due to interaction (REOI), proportion attributable to interaction (AP), and synergy index (S). We additionally analyzed cold waves over time to verify climate change. Under different definitions of cold waves, the odds ratio for the correlation between cold waves and outpatient visits for respiratory disease ranged from 0.95 (95% CI: 0.86, 1.05) to 1.58 (1.47, 1.70). Exposure to PM2.5 was significantly associated with an increase in outpatient visits for respiratory disease. We found that cold waves can synergize with PM2.5 to increase outpatient visits for respiratory disease (REOI > 0, AP > 0, S > 1), decreasing with stricter definitions of cold waves and longer durations. Cold waves' independent effect decreased over time, but their interaction effect persisted. From 8.1 to 21.8% of outpatient visits were due to cold waves and high-level PM2.5. People aged 0-14 and ≥ 65 were more susceptible to cold waves and PM2.5, with a significant interaction for those aged 15-64 and ≥ 65. Our study fills the gap on how extreme weather and PM2.5 synergistically affect respiratory disease outpatient visits in high-altitude regions. The synergy of cold waves and PM2.5 increases outpatient visits for respiratory disease, especially in the elderly. Cold wave warnings and PM2.5 reduction have major public health benefits.

Quantification of the Heat-Related Risk and Burden of Hospitalizations for Cause-Specific Injuries and Contribution of Human-Induced Climate Change: A Time-Stratified Case-Crossover Study in China.

Although ambient temperature has been linked with injury incidence, there have been few nationwide studies to quantify the temperature-related risk and burden of cause-specific injury hospitalizations. Additionally, the impact of human-induced climate change to injury burden remains unknown. Our objectives are to examine the associations between ambient temperature and injury hospitalizations from various causes and to quantify the contribution of human-induced warming to the heat-related burden. We collected injury hospitalization data from a nationwide hospital-based registry in China during 2000-2019. Using a time-stratified case-crossover design, we investigated the associations between daily mean temperature (°C) and cause-specific injury hospitalizations. We also quantified the burden of heat-related injuries under the scenarios with and without anthropogenic forcing, using the Detection and Attribution Model Intercomparison Project to assess the contribution of human-induced warming. Our study included a total of 988,087 patients with hospitalization records for injuries. Overall, compared to the temperature at minimum risk of hospitalization (), the relative risk of hospitalization at extreme hot temperature (30.8°C, 97.5th percentile) was 1.18 [95% confidence interval (CI): 1.14, 1.22], with an approximately linear association between temperature and hospitalization. Vulnerability to heat-related injuries was more pronounced among males, young ( years of age) or middle-aged (45-64 years of age) individuals, and those living in the North. The heat-related attributable fraction increased from 23.2% in the 2000s to 23.6% in the 2010s, with a corresponding increase in the contribution of human-induced change over time. In the 2010s, the heat-related attributable fractions for specific causes of injury ranged from 12.4% to 54.4%, with human-induced change accounting for 6.7% to 10.6% of the burden. This nationwide study presents new evidence of significant associations between temperature and cause-specific injury hospitalizations in China and highlights the increasing contribution of human-induced warming to the injury burden. https://doi.org/10.1289/EHP14057.

Health impacts of a cold wave and its economic loss assessment in China’s high-altitude city, Xining

ObjectiveAmidst climate change, extensive research has centered on the health impacts of heatwaves, yet the consequences of cold spells, particularly in cooler, higher-altitude regions, remain under-explored.MethodsAnalyzing climatic data and non-accidental mortality in Xining, China’s second-highest provincial capital, from 2016 to 2020, this study defines cold spells as daily mean temperatures below the 10th, 7.5th, or 5th percentiles for 2–4 consecutive days. A time-stratified case-crossover approach and distributional lag nonlinear modeling were used to assess the link between cold spells and mortality, calculating attributable fractions (AFs) and numbers (ANs) of deaths. The study also examined the impact of cold spells over different periods and analyzed the value of a statistical life (VSL) loss in 2018, a year with frequent cold spells. Stratified analyses by sex, age, and education level were conducted.ResultsA significant association was found between cold spells and non-accidental mortality, with a relative risk of 1.548 (95% CI: 1.300, 1.845). The AF was 33.48%, with an AN of 9,196 deaths during the study’s cold period. A declining trend in mortality risk was observed from 2019–2020. The 2018 VSL was approximately 2.875 billion CNY, about 1.75% of Xining’s GDP. Higher risks were noted among males, individuals aged ≥ 65, and those with lower education levels.ConclusionThe findings underscore the vulnerability and economic losses of high-altitude cities to cold spells. Implementing interventions such as improved heating, educational programs, and community support is vital for mitigating these adverse health effects.

Is short-term exposure to primary gaseous air pollutants associated with AIDS-related deaths? Evidence from a time-stratified case-crossover study.

Primary gaseous air pollutants have been associated with death from multiple causes, however, it remains unknown if they play a role in premature mortality among individuals living with HIV/AIDS. Data on HIV/AIDS patients were collected from the Hubei Provincial Center for Disease Control and Prevention, with a total of 1,467 AIDS-related deaths (ARD) between 2013 and 2020. Daily mean sulfur dioxide (SO2), nitrogen dioxide (NO2), and carbon monoxide (CO) were generated by artificial intelligence algorithms combined with big data. We employed a time-stratified case-crossover approach and conditional logistical regression models to investigate the acute effects of primary gaseous air pollutants on ARD. Per interquartile range increase in the concentrations of SO2 was significantly linked with ARD, with a corresponding odds ratio (OR) of 1.17 [95% confidence intervals (CIs): 1.01, 1.35] at lag 4day. Furthermore, our findings indicated that males exhibited a heightened vulnerability to the adverse effects of SO2 and NO2, for example, the ORs were 1.24 (95% CIs: 1.05, 1.47) and 1.16 (95% CIs: 1.01, 1.34), respectively. Moreover, individuals aged over 65years were more susceptible to SO2 and CO. Additionally, we identified the warm season as a sensitive period for mortality associated with SO2 and NO2. Our study furnished fresh evidence regarding the detrimental effects of primary gaseous air pollutants on ARD.

Green space and stroke: A scoping review of the evidence

BackgroundGlobal industrialisation and urbanisation has led to an increased interest in the link between the environment and health. Stroke is a major cause of morbidity and mortality, and there is increased evidence that environmental factors may affect both the incidence and severity of stroke. This review summarises the evidence for relationship between green space exposure and stroke incidence and outcomes. MethodsWe conducted a literature search in Medline and Scopus until 1 August 2023, and screened references of relevant articles. Selected articles were appraised for their relevance, and critically reviewed. The findings were thematically categorised. ResultsOf the 1342 papers identified, 27 were included. These involved a mix of study designs (cohort, cross-sectional, quasi-experimental, time stratified case crossover and ecological). There was consistent evidence indicating a protective association between green space exposure and disability and stroke-related death with mortality hazard ratios between 0.66 and 0.95. Most studies also showed that green space was inversely associated with stroke risk, with risk estimates from studies showing a protective effect ranging between 0.4 and 0.98; however, results were more mixed and some did not reach statistical significance. The moderating effects of green spaces on ambient temperatures, noise and air pollution, and psychosocial health plus greater enjoyment and opportunity for exercise and enrichment of the human microbiome may underly these associations. ConclusionThere is likely some protective effect of green space on stroke, with the benefits most convincingly shown for post-stroke outcomes. More research is recommended to confirm the protective association between green space exposure and reduced stroke risk.

Short-Term Increases in NO2 and O3 Concentrations during Pregnancy and Stillbirth Risk in the U.S.: A Time-Stratified Case-Crossover Study.

Associations between gaseous pollutant exposure and stillbirth have focused on exposures averaged over trimesters or gestation. We investigated the association between short-term increases in nitrogen dioxide (NO2) and ozone (O3) concentrations and stillbirth risk among a national sample of 116 788 Medicaid enrollees from 2000 to 2014. A time-stratified case-crossover design was used to estimate distributed (lag 0-lag 6) and cumulative lag effects, which were adjusted for PM2.5 concentration and temperature. Effect modification by race/ethnicity and proximity to hydraulic fracturing (fracking) wells was assessed. Short-term increases in the NO2 and O3 concentrations were not associated with stillbirth in the overall sample. Among American Indian individuals (n = 1694), a 10 ppb increase in NO2 concentrations was associated with increased stillbirth odds at lag 0 (5.66%, 95%CI: [0.57%, 11.01%], p = 0.03) and lag 1 (4.08%, 95%CI: [0.22%, 8.09%], p = 0.04) but not lag 0-6 (7.12%, 95%CI: [-9.83%, 27.27%], p = 0.43). Among participants living in zip codes within 15 km of active fracking wells (n = 9486), a 10 ppb increase in NO2 concentration was associated with increased stillbirth odds in single-day lags (2.42%, 95%CI: [0.37%, 4.52%], p = 0.02 for lag 0 and 1.83%, 95%CI: [0.25%, 3.43%], p = 0.03 for lag 1) but not the cumulative lag (lag 0-6) (4.62%, 95%CI: [-2.75%, 12.55%], p = 0.22). Odds ratios were close to the null in zip codes distant from fracking wells. Future studies should investigate the role of air pollutants emitted from fracking and potential racial disparities in the relationship between short-term increases in NO2 concentrations and stillbirth.

Ambient air pollution and visit of asthma patients: case study in DKI Jakarta 2017

Asthma is a worldwide disease that affects all races, ages, and genders. In 2017, asthma attacked 300 million people in the world. One risk factor for asthma is air pollution. The design of this study is a time-stratified case crossover, with secondary data types consisting of asthma visit data (ICD-10: J45) and pollutant data (PM10, O3, and NOx) in DKI Jakarta in 2017. The results from this study: Ozone exposure lag day 3 p = 0.04, OR = 1.0016 (95% CI 1,0001-1.003) and lag day 1 of NOx exposure p = 0.04, OR = 1.0050 (95% CI 1, 0003-1,010) which influences the visit of asthma patients in DKI Jakarta. It can be concluded that ozone and NOx are associated with asthma patient visits in DKI Jakarta, and this study on PM10 pollutants did not show any relationship with patient visits due to Asthma in DKI Jakarta.

Short-term ambient ozone exposure increases the risk of hospitalization with depression: a multi-city time-stratified case–crossover study

Background Depression, the most common mental illness worldwide, has been studied and air pollution has been found to increase the risk of depression hospitalization, but research results on ozone (O3) remain limited. In this context, we investigated the relationship between short-term O3 exposure and depression-related hospital admissions (HAs). Methods The 10,459 records of HAs for depression from medical institutions across in 9 cities, China, were collected between 1 January 2017, and 31 December 2018. Air pollutants and meteorological data was obtained from provincial ecological environment monitoring stations in the study area. Conditional Poisson regression was employed to estimate the association between O3 and hospitalizations for depression, with data stratification by sex, age, weather, and economic level. Results Short-term O3 exposure was positively associated with the number of depression-related hospitalizations (Relative risk: 1.04 [95% CI: 1.02, 1.05]). O3 had a significant effect on the risk of depression-related hospitalizations on warm days (P = 0.021, Relative risk: 1.05 [1.03, 1.08]). The high gross domestic product group was more likely to be affected by O3 exposure-associated depression-related hospitalizations (P = 0.005, Relative risk: 1.03 [1.01, 1.05]). Conclusions Short-term changes to O3 exposure may increase the risk of depression related hospitalizations, especially on warm days.

The Short-Term Effects and Burden of Ambient Air Pollution on Hospitalization for Type 2 Diabetes: Time-Stratified Case-Crossover Evidence From Sichuan, China.

Type 2 diabetes mellitus (T2DM), a complicated metabolic disease, might be developed or exacerbated by air pollution, resulting in economic and health burden to patients. So far, limited studies have estimated associations between short-term exposure to air pollution and disease burden of T2DM in China. Hence, we aimed to estimate the associations and burden of ambient air pollutants (NO2, PM10, PM2.5, SO2, and CO) on hospital admissions (HAs) for T2DM using a time-stratified case-crossover design. Data on HAs for T2DM during 2017-2019 were collected from hospital electronic health records in nine cities in Sichuan Province using conditional poisson regression. Totally, 92,381 T2DM hospitalizations were recorded. There were significant short-term effects of NO2, PM10, PM2.5, SO2 and CO on HAs for T2DM. A 10μg/m3 increment of NO2, PM10, PM2.5, SO2 and CO as linked with a 3.39% (95% CI: 2.26%, 4.54%), 0.33% (95% CI: 0.04%, 0.62%), 0.76% (95% CI: 0.35%, 1.16%), 12.68% (95% CI: 8.14%, 17.42%) and 79.00% (95% CI: 39.81%, 129.18%) increase in HAs for T2DM at lag 6. Stratified analyses modified by age, sex, and season showed old (≥65years) and female patients linked with higher impacts. Using WHO's air quality guidelines of NO2, PM10, PM2.5, and CO as the reference, the attributable number of T2DM HAs exceeding these pollutants exposures were 786, 323, 793, and 2,127 during 2017-2019. Besides, the total medical costs of 25.83, 10.54, 30.74, and 67.78 million China Yuan were attributed to NO2, PM10, PM2.5, and CO. In conclusion, short-term exposures to air pollutants were associated with higher risks of HAs for T2DM.

Mortality Risk and Burden From a Spectrum of Causes in Relation to Size-Fractionated Particulate Matters: Time Series Analysis.

There is limited evidence regarding the adverse impact of particulate matters (PMs) on multiple body systems from both epidemiological and mechanistic studies. The association between size-fractionated PMs and mortality risk, as well as the burden of a whole spectrum of causes of death, remains poorly characterized. We aimed to examine the wide range of susceptible diseases affected by different sizes of PMs. We also assessed the association between PMs with an aerodynamic diameter less than 1 µm (PM1), 2.5 µm (PM2.5), and 10 µm (PM10) and deaths from 36 causes in Guangzhou, China. Daily data were obtained on cause-specific mortality, PMs, and meteorology from 2014 to 2016. A time-stratified case-crossover approach was applied to estimate the risk and burden of cause-specific mortality attributable to PMs after adjusting for potential confounding variables, such as long-term trend and seasonality, relative humidity, temperature, air pressure, and public holidays. Stratification analyses were further conducted to explore the potential modification effects of season and demographic characteristics (eg, gender and age). We also assessed the reduction in mortality achieved by meeting the new air quality guidelines set by the World Health Organization (WHO). Positive and monotonic associations were generally observed between PMs and mortality. For every 10 μg/m3 increase in 4-day moving average concentrations of PM1, PM2.5, and PM10, the risk of all-cause mortality increased by 2.00% (95% CI 1.08%-2.92%), 1.54% (95% CI 0.93%-2.16%), and 1.38% (95% CI 0.95%-1.82%), respectively. Significant effects of size-fractionated PMs were observed for deaths attributed to nonaccidental causes, cardiovascular disease, respiratory disease, neoplasms, chronic rheumatic heart diseases, hypertensive diseases, cerebrovascular diseases, stroke, influenza, and pneumonia. If daily concentrations of PM1, PM2.5, and PM10 reached the WHO target levels of 10, 15, and 45 μg/m3, 7921 (95% empirical CI [eCI] 4454-11,206), 8303 (95% eCI 5063-11,248), and 8326 (95% eCI 5980-10690) deaths could be prevented, respectively. The effect estimates of PMs were relatively higher during hot months, among female individuals, and among those aged 85 years and older, although the differences between subgroups were not statistically significant. We observed positive and monotonical exposure-response curves between PMs and deaths from several diseases. The effect of PM1 was stronger on mortality than that of PM2.5 and PM10. A substantial number of premature deaths could be preventable by adhering to the WHO's new guidelines for PMs. Our findings highlight the importance of a size-based strategy in controlling PMs and managing their health impact.

Ambient Temperature and Nervous System Diseases-related Mortality in Japan from 2010 to 2019: A Time-Stratified Case-Crossover Analysis

Ambient Temperature and Nervous System Diseases-related Mortality in Japan from 2010 to 2019: A Time-Stratified Case-Crossover Analysis

Short-term exposure to ozone and mortality from AIDS-related diseases: A case-crossover study in the middle Yangtze River region, China

BackgroundPrevious investigations have predominantly concentrated on the influence of ozone (O3) on general population mortality. However, a noticeable gap exists regarding the attention directed towards susceptible demographics, specifically individuals afflicted by human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS). MethodsA dataset comprising 1467 AIDS-related fatalities from 2013 to 2020 was amassed from the Hubei Provincial Center for Disease Control and Prevention. Daily maximum 8-h average O3 levels and meteorological parameters were extracted from the ChinaHighAirPollutants dataset and the National Meteorological Science Data Center, respectively. A time-stratified case-crossover methodology was employed to scrutinize the connection between short-term exposure to O3 and AIDS-related deaths. ResultsA rise of one interquartile (IQR) in O3 concentration, lagged by 4 days, was associated with a 15% [95% confidence intervals (CIs): 2, 31] increase in AIDS-related deaths. Notably, males demonstrated heightened susceptibility to the adverse consequences of O3, marked by an odds ratio of 1.20 (95% CIs: 1.05, 1.37) at lag 4 day. Additionally, patients aged over 65 years exhibited escalated vulnerability to brief O3 exposure. Marriage status and educational attainment emerged as influential factors modifying the interplay between O3 and AIDS-related mortality. ConclusionsOur study presents novel evidence spotlighting the deleterious repercussions of O3 on mortality in the HIV/AIDS population.

Ambient Anthropogenic Carbons and Pediatric Respiratory Infections: A Case-Crossover Analysis in the Megacity Beijing.

Carbon loading in airway cells has shown to worsen function of antimicrobial peptides, permitting increased survival of pathogens in the respiratory tract; however, data on the impacts of carbon particles on childhood acute respiratory infection (ARI) is limited. We assembled daily health data on outpatient visits for ARI (bronchitis, pneumonia, and total upper respiratory infection [TURI]) in children aged 0-14years between 2015 and 2019 in Beijing, China. Anthropogenic carbons, including black carbon (BC) and its emission sources, and wood smoke particles (delta carbon, ultra-violet absorbing particulate matter, and brown carbon) were continuously monitored. Using a time-stratified case-crossover approach, conditional logistic regression was performed to derive risk estimates for each outcome. A total of 856,899 children were included, and a wide range of daily carbon particle concentrations was observed, with large variations for BC (0.36-20.44) and delta carbon (0.48-57.66μg/m3). Exposure to these particles were independently associated with ARI, with nearly linear exposure-response relationships. Interquartile range increases in concentrations of BC and delta carbon over prior 0-8days, we observed elevation of the odd ratio of bronchitis by 1.201 (95% confidence interval, 1.180, 1.221) and 1.048 (95% CI, 1.039, 1.057), respectively. Stronger association was observed for BC from traffic sources, which increased the odd ratio of bronchitis by 1.298 (95% CI, 1.273, 1.324). Carbon particles were also associated with elevated risks of pneumonia and TURI, and subgroup analyses indicated greater risks among children older than 6years. Our findings suggested that anthropogenic carbons in metropolitan areas may pose a significant threat to clinical manifestations of respiratory infections in vulnerable populations.

Associations Between Hourly Ambient Particulate Matter Air Pollution and Ambulance Emergency Calls: Time-Stratified Case-Crossover Study.

Associations between short-term exposure to ambient particulate matter (PM) air pollutants and mortality or hospital admissions have been well-documented in previous studies. Less is known about the associations of hourly exposure to PM air pollutants with ambulance emergency calls (AECs) for all causes and specific causes by conducting a case-crossover study. In addition, different patterns of AECs may be attributed to different seasons and daytime or nighttime periods. In this study, we quantified the risk of all-cause and cause-specific AECs associated with hourly PM air pollutants between January 1, 2013, and December 31, 2019, in Shenzhen, China. We also examined whether the observed associations of PM air pollutants with AECs for all causes differed across strata defined by sex, age, season, and the time of day. We used ambulance emergency dispatch data and environmental data between January 1, 2013, and December 31, 2019, from the Shenzhen Ambulance Emergency Centre and the National Environmental Monitor Station to conduct a time-stratified case-crossover study to estimate the associations of air pollutants (ie, PM with an aerodynamic diameter less than 2.5 µm [PM2.5] or 10 µm [PM10]) with all-cause and cause-specific AECs. We generated a well-established, distributed lag nonlinear model for nonlinear concentration response and nonlinear lag-response functions. We used conditional logistic regression to estimate odds ratios with 95% CIs, adjusted for public holidays, season, the time of day, the day of the week, hourly temperature, and hourly humidity, to examine the association of all-cause and cause-specific AECs with hourly air pollutant concentrations. A total of 3,022,164 patients were identified during the study period in Shenzhen. Each IQR increase in PM2.5 (24.0 µg/m3) and PM10 (34.0 µg/m3) concentrations over 24 hours was associated with an increased risk of AECs (PM2.5: all-cause, 1.8%, 95% CI 0.8%-2.4%; PM10: all-cause, 2.0%, 95% CI 1.1%-2.9%). We observed a stronger association of all-cause AECs with PM2.5 and PM10 in the daytime than in the nighttime (PM2.5: daytime, 1.7%, 95% CI 0.5%-3.0%; nighttime, 1.4%, 95% CI 0.3%-2.6%; PM10: daytime, 2.1%, 95% CI 0.9%-3.4%; nighttime, 1.7%, 95% CI 0.6%-2.8%) and in the older group than in the younger group (PM2.5: 18-64 years, 1.4%, 95% CI 0.6%-2.1%; ≥65 years, 1.6%, 95% CI 0.6%-2.6%; PM10: 18-64 years, 1.8%, 95% CI 0.9%-2.6%; ≥65 years, 2.0%, 95% CI 1.1%-3.0%). The risk of all-cause AECs increased consistently with increasing concentrations of PM air pollutants, showing a nearly linear relationship with no apparent thresholds. PM air pollution increase was associated with a higher risk of all-cause AECs and cardiovascular diseases-, respiratory diseases-, and reproductive illnesses-related AECs. The results of this study may be valuable to air pollution attributable to the distribution of emergency resources and consistent air pollution control.

Modification of low temperature-related hospital admissions for cardiovascular diseases by multiple green space indicators at multiple spatial scales: Evidence from Guangzhou, China

Extreme temperatures have an adverse effect on the occurrence of cardiovascular diseases (CVDs). Previous literatures tend to discuss the modification of CVDs occurrence by green space under high temperature. Relatively less attention is paid to the modification under low temperature. The variation of different attributes and spatial scales of green space in affecting CVDs occurrence are also overlooked. This study collected a total of 4364 first-time admission cases due to CVDs in a tertiary hospital in Guangzhou from 2012 to 2018, measured the scale of green space by greening rate (GR) and percentage of landscape (PLAND), the distribution of green space by patch density (PD), mean nearest neighbor distance (ENN_MN) and largest patch index (LPI), and the accessibility of green space by green patch accessibility index (GPAI). Using the time stratified case crossover design method, the modification of low temperature-related CVDs occurrence by the above green space indicators is evaluated in an area with a radius of 100-1000m which is further divided at an interval of 100m. We found high GR, high PLAND, high PD, low ENN_MN, high LPI, and low GPAI corresponds to low risk of CVDs occurrence, the optimal modification scale of each green space indicator, which is radius corresponding to the maximum risk difference between high and low indicator subgroups, is around 800m (GR), 600m (PLAND and PD), 500m (GPAI), and 300m (LPI and ENN_MN), respectively. As the temperature decreases further, the health benefit from low GPAI at the optimal scale is weakened, whereas the benefits from the others are strengthened. Low temperature related CVDs occurrence risk can be modified by multiple green space indicators, and these modifications have spatial scale effect. Our findings have important theoretical and practical significance for the formulation and implementation of local green space policies.

Wildfire smoke exposure and emergency department visits in Washington State

Wildfires are increasing in prevalence in western North America due to changing climate conditions. A growing number of studies examine the impact of wildfire smoke on morbidity; however, few evaluate these impacts using syndromic surveillance data that cover many emergency departments (EDs). We used syndromic surveillance data to explore the effect of wildfire smoke exposure on all-cause respiratory and cardiovascular ED visits in Washington state. Using a time-stratified case crossover design, we observed an increased odds of asthma visits immediately after and in all five days following initial exposure (lag 0 OR: 1.13; 95% CI: 1.10, 1.17; lag 1–5 ORs all 1.05 or greater with a lower CI of 1.02 or higher), and an increased odds of respiratory visits in all five days following initial exposure (lag 1 OR: 1.02; 95% CI: 1.00, 1.03; lag 2–5 ORs and lower CIs were all at least as large) comparing wildfire smoke to non-wildfire smoke days. We observed mixed results for cardiovascular visits, with evidence of increased odds emerging only several days following initial exposure. We also found increased odds across all visit categories for a 10 μg m−3 increase in smoke-impacted PM2.5. In stratified analyses, we observed elevated odds for respiratory visits among ages 19–64, for asthma visits among ages 5–64, and mixed risk estimates for cardiovascular visits by age group. This study provides evidence of an increased risk of respiratory ED visits immediately following initial wildfire smoke exposure, and increased risk of cardiovascular ED visits several days following initial exposure. These increased risks are seen particularly among children and younger to middle-aged adults.

49 Spatial variation in the effect of heat waves on pediatric acute care utilization in California (2000-2019)

OBJECTIVES/GOALS: The increasing frequency and severity of heat waves due to climate change present unique risks to children. We aim to assess how various heat wave definitions impact pediatric acute care utilization across California. We also hope to examine heat waves’localized effects at the zip code level and how contextual factors modulate these effects. METHODS/STUDY POPULATION: A time-stratified case crossover will evaluate the association between different heat wave definitions and pediatric acute care utilization throughout California. A within-community matched design analysis coupled with a bayesian model will examine heat waves’ effects at the zip code level. A random effect meta-regression will determine which contextual factors modulate heat waves’ impact on different zip codes. Temperature data will be pulled from Cal-Adapt and interpolated to each zip code population centroid. Data for all unscheduled pediatric hospitalizations and ED visits for selected ICD codes in California from 2000–2019 will be obtained from the California Department of Health Care Access and Information. Contextual factors will be sourced from the US Census and the Healthy Places Index. RESULTS/ANTICIPATED RESULTS: We anticipate that heat waves will be associated with increased pediatric acute care utilization throughout California for select ICD codes. At the zip code level, we anticipate that there will be considerable spatial variation in the association between heat waves and care utilization based on region and zip code characteristics. Furthermore, we expect to see significant variation in the association between heat waves and hospitalizations based on the selected heat wave definition. We predict that zip codes with the highest increases in care utilization will have higher percentages of non-white residents, lower socioeconomic status, and fewer heat protective factors like park density and tree coverage. DISCUSSION/SIGNIFICANCE: As global temperatures continue to rise, children will be increasingly susceptible to health consequences associated with heat exposure. Understanding which pediatric populations are most vulnerable during heat waves is critical for designing policies and interventions that protect the most vulnerable communities.