Cumulative Relative Risk Research Articles

Increased hospital admissions for asthma from short-term exposure to cold spells in Beijing, China.

There is a paucity of studies investigating extreme cold events and asthma exacerbations. This study examined whether an association exists between cold spells and daily hospital admissions for asthma in Beijing, China from 2012 to 2016. Daily hospital admissions for asthma, meteorological variables and air quality data were collected during 2012-2016 in Beijing. A cold spell was defined as a period of at least two consecutive days with the daily mean temperature below or at the 5th percentile (-7°C) in cold seasons (November to March) during the study period. We applied a time-series design using quasi-Poisson regression combined with a distributed lag model to estimate the risk of asthma hospital admissions associated with cold spells. Stratified analyses by gender and age groups were conducted to identify the potential susceptible subpopulations to cold spells. We also explored the effect modification by air quality by dividing the daily air quality index (AQI) into two levels (high and low) based on the median value. Cold spells increased the risk of asthma hospital admissions, with the maximum cumulative relative risk (CRR) over three weeks (Lag0-21) in the total population. The highest single-day relative risk (RR) was found on the days of cold spells (Lag0) with the RR=1.059 (95% CI: 1.008-1.113), and the CRR at Lag0-21 was 1.333 (95% CI: 1.049-1.693). Across different gender and age groups, younger people (<65 years) were more sensitive to cold spells. No significant effect modification by AQI was detected. Short-term exposure to cold spells is associated with an increased risk of hospital admissions for asthma in Beijing. During the cold spells, younger people aged <65 years were at particular risk for asthma exacerbations. Our results suggest that extreme cold events have a significant impact on asthma.

Changing heat impacts on mortality and implications for mitigation planning in New York City

BACKGROUND AND AIM: Heat mitigation planning requires careful characterization of the adverse impacts of temperature on health outcomes. New York City (NYC) has used observed temperature-mortality relationships to revise the city’s heat advisory trigger threshold, but such assessment must be ongoing as temperatures rise. METHODS: We analyzed 5-year rolling periods of weather and mortality data for May-September, 1997-2017 in NYC to estimate changes in cumulative relative risks (CRR) with up to 3-day lag and attributable deaths over time using both the extreme heat event (EHE) day indicator (0/1) for NYC’s heat advisory threshold (=35°C for two days or =38°C for any duration) and a continuous daily maximum heat index (or maximum temperature when heat index was unavailable), or MAX, using quasi-Poisson distributed lag non-linear models. For MAX, we used the median for the entire period (28°C) as reference, estimated CRRs at 37°C (median temperature of days above 35°C), compared to EHE CRR, and estimated attributable deaths for all days above 28°C. RESULTS:CRRs for both EHE and MAX have been comparable and stable (~1.08) in the recent decade and lower than in earlier periods (~1.10). The number of EHE days were stable over the study period (~10 days/year), while non-EHE summer days (28°C to less than 35°C) have been increasing (57 days in 1997-2001 vs. 74 days in 2013-2017). The estimated attributable deaths for MAX mirror the warming climate, increasing since 1997, and surpassing those for EHE in recent years (267 MAX vs 94 EHE for 2013-2017). CONCLUSIONS:Estimated excess deaths due to non-EHE days are larger than those for EHE days and increasing. In NYC, where the overall air conditioning prevalence is greater than 90%, near-term heat mitigation should focus on addressing inequities in air conditioning and energy insecurity in the most-impacted communities along with other structural heat mitigation strategies beyond emergency response. KEYWORDS: temperature, mortality, extreme heat, attributable deaths, heat mitigation

The mortality burden of nervous system diseases attributed to ambient temperature: A multi-city study in China

BackgroundsStudies on the association between ambient temperature and human mortality have been widely reported, focusing on common diseases such as cardiopulmonary diseases. However, multi-city studies on the association between both high and low temperatures and mortality of nervous system diseases were scarce, especially on the evidence of vulnerable populations. MethodsWeekly meteorological data, air pollution data and mortality data of nervous system were collected in 5 cities in China. A quasi-Poisson regression with distributed lag non-linear model (DLNM) was applied to quantify the association between extreme temperatures and mortality of nervous system diseases. Multivariate meta-analysis was applied to estimate the pooled effects at the overall levels. The attributable fractions (AFs) were calculated to assess the mortality burden attributable to both high and low temperatures. Stratified analyses were also performed by gender and age-groups through the above steps. ResultsA total of 12,132 deaths of nervous system diseases were collected in our study. The overall minimum mortality temperature was 23.9 °C (61.9th), the cumulative relative risks of extreme heat and cold for nervous system diseases were 1.33(95%CI: 1.10, 1.61) and 1.47(95%CI: 1.27, 1.71). The mortality burden attributed to non-optimal temperatures accounted for 29.54% (95%eCI: 13.45%, 40.52%), of which the mortality burden caused by low temperature and high temperature accounted for 25.89% (95%eCI: 13.03%, 34.36%) and 3.65% (95%eCI: 0.42%, 6.17%), respectively. The mortality burden attributable to ambient temperature was higher in both males and the elderly (>74 years old), with the AF of 31.85% (95%eCI: 20.68%, 39.88%) and 31.14% (95%eCI: −6.83%, 49.51%), respectively. ConclusionsThe non-optimal temperature can increase the mortality of nervous system diseases and the males and the elderly over 74 years have the highest attributable burden. The findings add the evidence of vulnerable populations of nervous system diseases against ambient temperatures.

Association between ozone exposure and prevalence of mumps: a time-series study in a Megacity of Southwest China.

In the present study, we aim to evaluate the delayed and cumulative effect of ozone (O3) exposure on mumps in a megacity with high population density and high humidity. We took Chongqing, a megacity in Southwest China, as the research area and 2013–2017 as the research period. A total of 49,258 confirmed mumps cases were collected from 122 hospitals of Chongqing. We employed the distributed lag nonlinear models with quasi-Poisson link to investigate the relationship between prevalence of mumps and O3 exposure after adjusting for the effects of meteorological conditions. The results show that the effect of O3 exposure on mumps was mainly manifested in the lag of 0–7 days. The single-day ;lag effect was the most obvious on the 4th day, with the relative risk (RR) of mumps occurs of 1.006 (95% CI: 1.003–1.007) per 10 μg/m3 in the O3 exposure. The cumulative RR within 7 days was 1.025 (95% CI: 1.013–1.038). Our results suggest that O3 exposure can increase the risk of mumps infection, which fills the gap of relevant research in mountainous areas with high population density and high humidity.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11356-021-15473-2.

Consumption of Alcohol, Cannabis, and Tobacco in a Cohort of Adolescents before and during COVID-19 Confinement.

The aim of this study was to identify changes in the hazardous consumption of alcohol, tobacco, and cannabis, due to the COVID-19 lockdown in 2020 in a cohort of schooled adolescents from Central Catalonia. We also analyzed the effect of the individual and social factors on risky consumption during confinement. This longitudinal study involved a subsample of 303 adolescents aged 14–18 years, who were attending 4th year of compulsory secondary education (ESO), 2nd year of college preparation (baccalaureate), or Vocational and Educational Training (VET). We collected data before COVID-19 lockdown (October 2019–February 2020) and 2 months after the lockdown ended. We estimated the prevalence of risky substance use in the sample at baseline for each independent variable. We used Poisson regression models with robust variance to compute the Cumulative Incidence (CI) and Relative Risk (RR), with their respective 95% confidence interval. We found that VET students had a significantly (p < 0.05) higher risk of substance use: binge drinking (RR = 3.21 (95%CI: 1.00–10.34)); hazardous drinking of alcohol (RR = 3.75 (95%CI: 1.12–12.54)), hazardous consumption of cannabis (RR = 3.75 (95%CI: 0.65–21.59)) and daily smoking of tobacco (RR = 4.82 (95%CI: 1.74–13.39)). The results showed a general trend of reduction of consumption during COVID-19 confinement period. This study suggests that VET students were more likely to engage in hazardous drinking of alcohol and daily smoking of tobacco. No statistically significant differences were found for the other age groups and variables.

Association between ambient temperature and atopic dermatitis in Lanzhou, China: a time series analysis.

Many studies have explored the association between temperature and atopic dermatitis (AD); however, the results are inconsistent. We used a quasi-Poisson function fitted to a distributed lag nonlinear model (DLNM) to evaluate the association between daily average temperature and AD outpatient visits from January 1, 2013, to December 31, 2019, in Lanzhou, China. We found that the exposure-response association curve was inversely "s-shaped," low-temperature effects occurred at a lag of 11 days and then lasted for 10 days, and high-temperature effects occurred on the current day and then significantly decreased. Both low and high ambient temperatures can increase the risk of outpatient visits. Compared with median temperature (12.89°C), the cumulative relative risk (RR) of extreme high temperature and moderate-high temperature were 1.847 (95% confidence interval [CI]: 1.613, 2.114) and 1.447 (95% CI: 1.298, 1.614), respectively, at lag0-7 days, and the cumulative RRs of extremely low temperature and moderate-low temperature were 1.004 (95% CI: 0.904, 1.115) and 1.056 (95% CI: 0.925, 1.205), respectively, at lag0-21 days. Females were more sensitive to high temperatures than males, and high or low temperatures had significant effects on children ≤14 years of age. Graphical abstract.

The exposure-response association between humidex and bacillary dysentery: A two-stage time series analysis of 316 cities in mainland China

BackgroundMany studies have reported the interactive effects between relative humidity and temperature on infectious diseases. However, evidence regarding the combined effects of relative humidity and temperature on bacillary dysentery (BD) is limited, especially for large-scale studies. To address this research need, humidex was utilized as a comprehensive index of relative humidity and temperature. We aimed to estimate the effect of humidex on BD across mainland China, evaluate its heterogeneity, and identify potential effect modifiers. MethodsDaily meteorological and BD surveillance data from 2014 to 2016 were obtained for 316 prefecture-level cities in mainland China. Humidex was calculated on the basis of relative humidity and temperature. A multicity, two-stage time series analysis was then performed. In the first stage, a common distributed lag non-linear model (DLNM) was established to obtain city-specific estimates. In the second stage, a multivariate meta-analysis was conducted to pool these estimates, assess the significance of heterogeneity, and explore potential effect modifiers. ResultsThe pooled cumulative estimates showed that humidex could promote the transmission of BD. The exposure-response relationship was nearly linear, with a maximum cumulative relative risk (RR) of 1.45 [95% confidence interval (CI): 1.29–1.63] at a humidex value of 40.94. High humidex had an acute adverse effect on BD. The humidex-BD relationship could be modified by latitude, urbanization rate, the natural growth rate of population, and the number of primary school students per thousand persons. ConclusionsHigh humidex could increase the risk of BD incidence. Thus, it is suitable to incorporate humidex as a predictor into the early warning system of BD and to inform the general public in advance to be cautious when humidex is high. This is especially true for regions with higher latitude, higher urbanization rates, lower natural growth rates of population, and lower numbers of primary school students per thousand persons.

The short-term associations of chronic obstructive pulmonary disease hospitalizations with meteorological factors and air pollutants in Southwest China: a time-series study

Chronic obstructive pulmonary disease (COPD) is the fourth major cause of mortality and morbidity worldwide and is projected to be the third by 2030. However, there is little evidence available on the associations of COPD hospitalizations with meteorological factors and air pollutants in developing countries/regions of Asia. In particular, no study has been done in western areas of China considering the nonlinear and lagged effects simultaneously. This study aims to evaluate the nonlinear and lagged associations of COPD hospitalizations with meteorological factors and air pollutants using time-series analysis. The modified associations by sex and age were also investigated. The distributed lag nonlinear model was used to establish the association of daily COPD hospitalizations of all 441 public hospitals in Chengdu, China from Jan/2015–Dec/2017 with the ambient meteorological factors and air pollutants. Model parameters were optimized based on quasi Akaike Information Criterion and model diagnostics was conducted by inspecting the deviance residuals. Subgroup analysis by sex and age was also performed. Temperature, relative humidity, wind and Carbon Monoxide (CO) have statistically significant and consistent associations with COPD hospitalizations. The cumulative relative risk (RR) was lowest at a temperature of 19℃ (relative humidity of 67%). Both extremely high and low temperature (and relative humidity) increase the cumulative RR. An increase of wind speed above 4 mph (an increase of CO above 1.44 mg/m3) significantly decreases (increases) the cumulative RR. Female populations were more sensitive to low temperature and high CO level; elderly (74+) populations are more sensitive to high relative humidity; younger populations (< = 74) are more susceptible to CO higher than 1.44 mg/m3. Therefore, people with COPD should avoid exposure to adverse environmental conditions of extreme temperatures and relative humidity, low wind speed and high CO level, especially for female and elderly patients who were more sensitive to extreme temperatures and relative humidity.

The modification effect of temperature on the relationship between air pollutants and daily incidence of influenza in Ningbo, China

BackgroundAlthough exposure to air pollution has been linked to many health issues, few studies have quantified the modification effect of temperature on the relationship between air pollutants and daily incidence of influenza in Ningbo, China.MethodsThe data of daily incidence of influenza and the relevant meteorological data and air pollution data in Ningbo from 2014 to 2017 were retrieved. Low, medium and high temperature layers were stratified by the daily mean temperature with 25th and 75th percentiles. The potential modification effect of temperature on the relationship between air pollutants and daily incidence of influenza in Ningbo was investigated through analyzing the effects of air pollutants stratified by temperature stratum using distributed lag non-linear model (DLNM). Stratified analysis by sex and age were also conducted.ResultsOverall, a 10 μg/m3 increment of O3, PM2.5, PM10 and NO2 could increase the incidence risk of influenza with the cumulative relative risk of 1.028 (95% CI 1.007, 1.050), 1.061 (95% CI 1.004, 1.122), 1.043 (95% CI 1.003, 1.085), and 1.118 (95% CI 1.028, 1.216), respectively. Male and aged 7–17 years were more sensitive to air pollutants. Through the temperature stratification analysis, we found that temperature could modify the impacts of air pollution on daily incidence of influenza with high temperature exacerbating the impact of air pollutants. At high temperature layer, male and the groups aged 0–6 years and 18–64 years were more sensitive to air pollution.ConclusionTemperature modified the relationship between air pollution and daily incidence of influenza and high temperature would exacerbate the effects of air pollutants in Ningbo.

The association between air pollution and COVID-19 related mortality in Santiago, Chile: A daily time series analysis

BackgroundExposure to ambient air pollution is a risk factor for morbidity and mortality from lung and heart disease. Research questionDoes short term exposure to ambient air pollution influence COVID-19 related mortality? Study design and methodologyUsing time series analyses we tested the association between daily changes in air pollution measured by stationary monitors in and around Santiago, Chile and deaths from laboratory confirmed or suspected COVID-19 between March 16 and August 31, 2020. Results were adjusted for temporal trends, temperature and humidity, and stratified by age and sex. ResultsThere were 10,069 COVID-19 related deaths of which 7659 were laboratory confirmed. Using distributed lags, the cumulative relative risk (RR) (95% CI) of mortality for an interquartile range (IQR) increase in CO, NO2 and PM2.5 were 1.061 (1.033–1.089), 1.067 (1.023–1.103) and 1.058 (1.034–1.082), respectively There were no significant differences in RR by sex.. In those at least 85 years old, an IQR increase in NO2 was associated with a 12.7% (95% CI 4.2–22.2) increase in daily mortality. ConclusionThis study provides evidence that daily increases in air pollution increase the risk of dying from COVID-19, especially in the elderly.

The effect of air temperature on hospital admission of adults with community acquired pneumonia in Baotou, China

The relationship between air temperature and the hospital admission of adult patients with community-acquired pneumonia (CAP) was analyzed. The hospitalization data pertaining to adult CAP patients (age ≥ 18 years) in two tertiary comprehensive hospitals in Baotou, Inner Mongolia Autonomous Region, China from 2014 to 2018 and meteorological data there in the corresponding period were collected. The exposure–response relationship between the daily average temperature and the hospital admission of adult CAP patients was quantified by using a distributed lag non-linear model. A total of 4466 cases of adult patients with CAP were admitted. After eliminating some confounding factors such as relative humidity, wind speed, air pressure, long-term trend, and seasonal trend, a lower temperature was found to be associated with a higher risk of adult CAP. Compared to 21 °C, lower temperature range of 4 to –12 °C was associated with a greater number of CAP hospitalizations among those aged ≥ 65 years, and the highest relative risk (RR) was 2.80 (95% CI 1.15–6.80) at a temperature of − 10 °C. For those < 65 years, lower temperature was not related to CAP hospitalizations. Cumulative lag RRs of low temperature with CAP hospitalizations indicate that the risk associated with colder temperatures appeared at a lag of 0–7 days. For those ≥ 65 years, the cumulative RR of CAP hospitalizations over lagging days 0–5 was 1.89 (95% CI 1.01–3. 56). In brief, the lower temperature had age-specific effects on CAP hospitalizations in Baotou, China, especially among those aged ≥ 65 years.

Associations between floods and bacillary dysentery cases in main urban areas of Chongqing, China, 2005\u20132016: a retrospective study

BackgroundUnderstanding the association between floods and bacillary dysentery (BD) incidence is necessary for us to assess the health risk of extreme weather events. This study aims at exploring the association between floods and daily bacillary dysentery cases in main urban areas of Chongqing between 2005 and 2016 as well as evaluating the attributable risk from floods.MethodsThe association between floods and daily bacillary dysentery cases was evaluated by using distributed lag non-linear model, controlling for meteorological factors, long-term trend, seasonality, and day of week. The fraction and number of bacillary dysentery cases attributable to floods was calculated. Subgroup analyses were conducted to explore the association across age, gender, and occupation.ResultsAfter controlling the impact of temperature, precipitation, relative humidity, long-term trend, and seasonality, a significant lag effect of floods on bacillary dysentery cases was found at 0-day, 3-day, and 4-day lag, and the cumulative relative risk (CRR) over a 7-lag day period was 1.393 (95%CI 1.216–1.596). Male had higher risk than female. People under 5 years old and people aged 15–64 years old had significantly higher risk. Students, workers, and children had significantly higher risk. During the study period, based on 7-lag days, the attributable fraction of bacillary dysentery cases due to floods was 1.10% and the attributable number was 497 persons.ConclusionsThis study confirms that floods can increase the risk of bacillary dysentery incidence in main urban areas of Chongqing within an accurate time scale, the risk of bacillary dysentery caused by floods is still serious. The key population includes male, people under 5 years old, students, workers, and children. Considering the lag effect of floods on bacillary dysentery, the government and public health emergency departments should advance to the emergency health response in order to minimize the potential risk of floods on public.

A time series analysis of the short-term association between climatic variables and acute respiratory infections in Singapore.

Acute respiratory infections (ARIs) are among the most common human illnesses globally. Previous studies that examined the associations between climate variability and ARIs or ARI pathogens have reported inconsistent findings. Few studies have been conducted in Southeast Asia to date, and the impact of climatic factors are not well-understood. This study aimed to investigate the short-term associations between climate variability and ARIs in Singapore. We obtained reports of ARIs from all government primary healthcare services from 2005 to 2019 and analysed their dependence on mean ambient temperature, minimum temperature and maximum temperature using the distributed lag non-linear framework. Separate negative binomial regression models were used to estimate the association between each temperature (mean, minimum, maximum temperature) and ARIs, adjusted for seasonality and long-term trend, rainfall, relative humidity, public holidays and autocorrelations. For temperature variables and relative humidity we reported cumulative relative risks (RRs) at 10th and 90th percentiles compared to the reference value (centered at their medians) with corresponding 95% confidence intervals (CIs). For rainfall we reported RRs at 50th and 90th percentiles compared to 0mm with corresponding 95% CIs. Statistically significant inverse S-curve shaped associations were observed between all three temperature variables (mean, minimum, maximum) and ARIs. A decrease of 1.1°C from the median value of 27.8°C to 26.7°C (10th percentile) in the mean temperature was associated with a 6% increase (RR: 1.06, 95% CI: 1.03 to 1.09) in ARIs. ARIs also increased at 23.9°C (10th percentile)compared to 24.9°C of minimum temperature (RR: 1.11, 95% CI: 1.07 to 1.16). The effect of maximum temperature for the same comparison (30.5°C vs 31.7°C) was non-significant (RR: 1.02, 95% CI: 0.99 to 1.05). An increase in ambient temperature to 28.9 °C (90th percentile) was associated with an 18% decrease (RR: 0.82, 95% CI: 0.80 to 0.83) in ARIs. Similarly, ARIs decreased with the same increase to 90th percentile in minimum (RR: 0.84, 95% CI: 0.80 to 0.87) and maximum (RR: 0.89, 95% CI: 0.86 to 0.93) temperatures. Rainfall was inversely associated with ARIs and displayed similar shape in all three temperature models. Relative humidity, on the other hand, exhibited a U-shaped relationship with ARIs. Our findings suggest that lower temperatures increase the risk of ARIs. Anticipated extreme weather events that reduce ambient temperature can be used to inform increased healthcare resource allocation for ARIs.

Impact of meteorological factors on hospital admissions for spinal diseases in Shanghai during 2015-2019

ABSTRACT Purpose: To assess the correlation between meteorological factors and spinal disease admissions. Methods: Data was obtained from the electronic medical records of a tertiary general hospital. Meteorological data was collected from China Meteorological Science Data Sharing Service. Distributed lag nonlinear models were used to evaluate the impact of meteorological variables on weekly spinal disease admissions. Results: A total of 2739 spinal cases were documented. Compared with estimates at the 50th, the cumulative relative risk (RR) for extremely high temperatures at the 97.5th over lag week 18 to lag week 20 increased by 75.7%. When the weekly maximum temperature reached 38°C during lag week 20, the maximum RR was 1.96 (95% CI:1.095–3.506). Moreover, the effects of extremely high temperatures on spinal disease admissions were more obvious in females and the age group ≥65 years old compared with males and the age group<65 years old. Conclusions: Extremely high temperatures were significantly associated with higher risks of spinal disease admissions.

Short-term effects of ambient temperature and pollutants on the mortality of respiratory diseases: A time-series analysis in Hefei, China

BackgroundThe air pollution has become an important environmental health problem due to its adverse health effect. The objective of this study was to investigate the effects of ambient temperature and pollutants on mortality of respiratory diseases (RD) in Hefei, China, a typical inland city. MethodsNonlinear exposure–response dependencies and delayed effects of urban daily mean temperature (DMT) and pollutants were evaluated by distributed lag non-linear models (DLNM). To further explore this effect, different genders and ages were also examined by stratified analysis. ResultsA total of 12876 deaths from RD were collected from January 1, 2014 to December 31, 2018 in Hefei, China. There was a U-shaped correlation between DMT and RD mortality, and the RD mortality rised by 11.6% (95% CI: 2.2–22.0%) when the DMT was 35.8 °C (reference temperature is 20 °C). The results show that risk of death with short-term exposure to elevated concentrations of PM10 and SO2 was not significant. The maximum hysteresis and cumulative relative risk (RR) of RD mortality were 1.012 (95% CI: 1.003 ~ 1.021, lag 0 day) and 1.072 (95% CI: 1.014 ~1.133, lag 10 days) for each 10 μg/m3 augment in NO2; 1.005 (95% CI: 1.001–1.009, lag 0 day) and 1.027 (95% CI: 1.004–1.051, lag 10 days) for each 10 μg/m3 augment in O3; a negative association between CO exposure and the cumulative risk of death was observed (RR = 0.964, 95% CI: 0.935–0.993, lag 07 days). Subgroup analysis showed the effect of high temperatures, NO2, O3 and CO exposure was still statistically significant for the elderly and male. ConclusionThe present study found that short-term exposure to high temperature, NO2, O3 and CO were significantly associated with the risk of RD mortality and male as well as elderly are more susceptible to these factors.

Emergency hospital admissions for cardiovascular diseases attributed to air pollution in Tehran during 2016-2019.

The burden of five main air pollutants, including CO, O3, NO2, SO2, and PM2.5, on the emergency department visits (EDVs) during January 2016-December 2019 due to all cardiovascular diseases was assessed in Tehran by using a time-series model. The pollutants data were collected from Iran Department of Environment including 10 air pollution monitoring stations for the period of our study. Cumulative relative risk and attributable number/fraction were calculated for each pollutants by a Quasi-Poisson time-series regression and distributed lag non-linear model (DLNM). The maximum lag was set to 14 days because harvesting effect is more likely happened during few days. We used percentile 25 as reference value in order to calculate cumulative relative risk and attributable fraction. About 69,000 patients with cardiovascular symptoms have been admitted into the hospital during 4 years. The cumulative relative risk during the 14 days was 1.13 (1.01, 1.26), 1.15 (1.02, 1.29), and 1.08 (1.01, 1.18) for CO, NO2, and PM2.5, respectively. The numbers attributed to all values of CO were more than others; about 3800 EDVs were significantly attributed to CO, of which over 3000 were significantly attributed to high values of the pollutant. Low values of all pollutants were, not surprisingly, responsible for low number of EDVs. PM2.5, CO, and NO2 were responsible to considerable attributable number of EDVs. Our study emphasizes the need for local authorities to establish a program to reduce the air pollution in Tehran.

Association between ambient temperature and childhood respiratory hospital visits in Beijing, China: a time-series study (2013-2017).

Little is known on the potential impact of temperature on respiratory morbidity, especially for children whose respiratory system can be more vulnerable to climate changes. In this time-series study, Poisson generalized additive models combined with distributed lag nonlinear models were used to assess the associations between ambient temperature and childhood respiratory morbidity. The impacts of extreme cold and hot temperatures were calculated as cumulative relative risks (cum.RRs) at the 1st and 99th temperature percentiles relative to the minimum morbidity temperature percentile. Attributable fractions of respiratory morbidity due to cold or heat were calculated for temperatures below or above the minimum morbidity temperature. Effect modifications by air pollution, age, and sex were assessed in stratified analyses. A total of 877,793 respiratory hospital visits of children under 14 years old between 2013 and 2017 were collected from Beijing Children's Hospital. Overall, we observed J-shaped associations with greater respiratory morbidity risks for exposure to lower temperatures, and higher fraction of all-cause respiratory hospital visits was caused by cold (33.1%) than by heat (0.9%). Relative to the minimum morbidity temperature (25 °C, except for rhinitis, which is 31 °C), the cum.RRs for extreme cold temperature (-6 °C) were 2.64 (95%CI: 1.51-4.61) for all-cause respiratory hospital visits, 2.73 (95%CI: 1.44-5.18) for upper respiratory infection, 2.76 (95%CI: 1.56-4.89) for bronchitis, 2.12 (95%CI: 1.30-3.47) for pneumonia, 2.06 (95%CI: 1.27-3.34) for rhinitis, and 4.02 (95%CI: 2.14-7.55) for asthma, whereas the associations between extreme hot temperature (29 °C) and respiratory hospital visits were not significant. The impacts of extreme cold temperature on asthma hospital visits were greater at higher levels of ozone (O3) exposure (> 50th percentile). Our findings suggest significantly increased childhood respiratory morbidity risks at extreme cold temperature, and the impact of extreme cold temperature on asthma hospital visits can be enhanced under higher level exposure to O3.

Daily mean temperature and HFMD: risk assessment and attributable fraction identification in Ningbo China

BackgroundHand, foot, and mouth disease (HFMD) remains a significant public health issue, especially in developing countries. Many studies have reported the association between environmental temperature and HFMD. However, the results are highly heterogeneous in different regions. In addition, there are few studies on the attributable risk of HFMD due to temperature.ObjectivesThe study aimed to assess the association between temperature and HFMD incidence and to evaluate the attributable burden of HFMD due to temperature in Ningbo China.MethodsThe research used daily incidence of HFMD from 2014 to 2017 and distributed lag non-linear model (DLNM) to investigate the effects of daily mean temperature (Tmean) on HFMD incidence from lag 0 to 30 days, after controlling potential confounders. The lag effects and cumulative relative risk (CRR) were analyzed. Attributable fraction (AF) of HFMD incidence due to temperature was calculated. Stratified analysis by gender and age were also conducted.ResultsThe significant associations between Tmean and HFMD incidence were observed in Ningbo for lag 0–30. Two peaks were observed at both low (5–11 °C) and high (16–29 °C) temperature scales. For low temperature scale, the highest CRR was 2.22 (95% CI: 1.61–3.07) at 7 °C on lag 0–30. For high temperature scale, the highest CRR was 3.54 (95% CI: 2.58–4.88) at 24 °C on lag 0–30. The AF due to low and high temperature was 5.23% (95% CI: 3.10–7.14%) and 39.55% (95% CI: 30.91–45.51%), respectively. There was no significant difference between gender- and age-specific AFs, even though the school-age and female children had slightly higher AF values.ConclusionsThe result indicates that both high and low temperatures were associated with daily incidence of HFMD, and more burdens were caused by heat in Ningbo.

Risk of ambulance services associated with ambient temperature, fine particulate and its constituents

Short-term adverse health effects of constituents of fine particles with aerodynamic diameters less than or equal to 2.5 μm (PM2.5) have been revealed. This study aimed to evaluate the real-time health outcome of ambulance services in association with ambient temperature and mass concentrations of total PM2.5 level and constituents in Kaohsiung City, an industrialized city with the worst air quality in Taiwan. Cumulative 6-day (lag0-5) relative risk (RR) and 95% confidence interval (CI) of daily ambulance services records of respiratory distress, coma and unconsciousness, chest pain, headaches/dizziness/vertigo/fainting/syncope, lying at public, and out-of-hospital cardiac arrest (OHCA) in association with ambient temperature and mass concentrations of total PM2.5 level and constituents (nitrate, sulfate, organic carbon (OC), and elemental carbon (EC)) from 2006 to 2010 were evaluated using a distributed lag non-linear model with quasi-Poisson function. Ambulance services of chest pain and OHCA were significantly associated with extreme high (30.8 °C) and low (18.2 °C) temperatures, with cumulative 6-day RRs ranging from 1.37 to 1.67 at the reference temperature of 24–25 °C. Daily total PM2.5 level had significant effects on ambulance services of lying at public and respiratory distress. After adjusting the cumulative 6-day effects of temperature and total PM2.5 level, RRs of ambulance services of lying at public associated with constituents at 90th percentile versus 25th percentile were 1.35 (95% CI: 1.08, 1.68) for sulfate and 1.20 (95% CI: 1.02, 1.41) for EC, while RR was 1.31 (95% CI: 1.09–1.58) for ambulance services of headache/dizziness/vertigo/fainting/syncope in association with OC at 90th percentile versus 25th percentile. Cause-specific ambulance services had various significant association with daily temperature, total PM2.5 level, and concentrations of constituents. Elemental carbon may have stronger associations with increased ambulance services than other constituents.

The association between ambient temperature and mortality of the coronavirus disease 2019 (COVID-19) in Wuhan, China: a time-series analysis

BackgroundThe COVID-19 has caused a sizeable global outbreak and has been declared as a public health emergency of international concern. Sufficient evidence shows that temperature has an essential link with respiratory infectious diseases. The objectives of this study were to describe the exposure-response relationship between ambient temperature, including extreme temperatures, and mortality of COVID-19.MethodsThe Poisson distributed lag non-linear model (DLNM) was constructed to evaluate the non-linear delayed effects of ambient temperature on death, by using the daily new death of COVID-19 and ambient temperature data from January 10 to March 31, 2020, in Wuhan, China.ResultsDuring the period mentioned above, the average daily number of COVID-19 deaths was approximately 45.2. Poisson distributed lag non-linear model showed that there was a non-linear relationship (U-shape) between the effect of ambient temperature and mortality. With confounding factors controlled, the daily cumulative relative death risk decreased by 12.3% (95% CI [3.4, 20.4%]) for every 1.0 °C increase in temperature. Moreover, the delayed effects of the low temperature are acute and short-term, with the most considerable risk occurring in 5–7 days of exposure. The delayed effects of the high temperature appeared quickly, then decrease rapidly, and increased sharply 15 days of exposure, mainly manifested as acute and long-term effects. Sensitivity analysis results demonstrated that the results were robust.ConclusionsThe relationship between ambient temperature and COVID-19 mortality was non-linear. There was a negative correlation between the cumulative relative risk of death and temperature. Additionally, exposure to high and low temperatures had divergent impacts on mortality.