Short-Term Ambient Air Pollution Exposure and Risk of Out-of-Hospital Cardiac Arrest in Sweden: A Nationwide Case-Crossover Study.

Background Air pollution is one of the main risk factors for cardiovascular disease globally, but its association with out-of-hospital cardiac arrest at low air pollution levels is unclear. This nationwide study in Sweden aims to investigate if air pollution is associated with a higher risk of out-of-hospital cardiac arrest in an area with relatively low air pollution levels. Methods and Results This study was a nationwide time-stratified case-crossover study investigating the association between short-term air pollution exposures and out-of-hospital cardiac arrest using data from the SRCR (Swedish Registry for Cardiopulmonary Resuscitation) between 2009 and 2019. Daily air pollution levels were estimated in 1×1-km grids for all of Sweden using a satellite-based machine learning model. The association between daily air pollutant levels and out-of-hospital cardiac arrest was quantified using conditional logistic regression adjusted for daily air temperature. Particulate matter <2.5 µm exposure was associated with a higher risk of out-of-hospital cardiac arrest among a total of 29 604 cases. In a multipollutant model, the association was most pronounced for intermediate daily lags, with an increased relative risk of 6.2% (95% CI, 1.0-11.8) per 10 µg/m3 increase of particulate matter <2.5 µm 4 days before the event. A similar pattern of association was observed for particulate matter <10 µm. No clear association was observed for O3 and NO2. Conclusions Short-term exposure to air pollution was associated with higher risk of out-of-hospital cardiac arrest. The findings add to the evidence of an adverse effect of particulate matter on out-of-hospital cardiac arrest, even at very low levels below current regulatory standards.

Short-term ambient air pollution exposure and risk of atrial fibrillation in patients with intracardiac devices.

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with substantial morbidity and mortality. Short-term exposure to fine particulate matter (PM2.5) has been causally linked to higher risk of cardiovascular disease, but the association with atrial fibrillation (AF) is less clear. Methods: We conducted a time-stratified case-crossover study to estimate the association between short-term air pollution levels and risk of AF episodes. The episodes were identified among patients with paroxysmal AF and an intracardiac devices able to register and store AF episodes. We obtained air pollution and temperature data from fixed monitoring stations and used conditional logistic regression to quantify the association of PM2.5, particulate matter (PM10), nitrogen dioxide (NO2) and ozone (O3) with onset of AF episodes, adjusting for temperature and public holidays.". Results: We analyzed 584 episodes of AF from 91 participants and observed increased risk of AF episodes with PM2.5 levels for the 48-72 hours lag (OR 1.05; CI [1.01,1.09] per IQR)] and 72-96 hours (OR 1.05 CI [1.00,1.10] per IQR). Our results were suggestive of an association between O3 levels and AF episodes during the warm season. We did not observe any statistically significant associations for PM10 nor NO2. Conclusion: Short-term increases in PM2.5 in a low-pollution level environment were associated with increased risk of AF episodes in a population with intracardiac devices. Our findings add to the evidence of a potential triggering of AF by short-term increases in air pollution levels, well below the new WHO air quality guidelines.

Ambient air pollution and cardiovascular diseases: An umbrella review of systematic reviews and meta-analyses.

The available evidence on the effects of ambient air pollution on cardiovascular diseases (CVDs) has increased substantially. In this umbrella review, we summarized the current epidemiological evidence from systematic reviews and meta-analyses linking ambient air pollution and CVDs, with a focus on geographical differences and vulnerable subpopulations. We performed a search strategy through multiple databases including articles between 2010 and 31 January 2021. We performed a quality assessment and evaluated the strength of evidence. Of the 56 included reviews, the most studied outcomes were stroke (22 reviews), all-cause CVD mortality, and morbidity (19). The strongest evidence was found between higher short- and long-term ambient air pollution exposure and all-cause CVD mortality and morbidity, stroke, blood pressure, and ischemic heart diseases (IHD). Short-term exposures to particulate matter <2.5 µm (PM2.5 ), <10 µm (PM10 ), and nitrogen oxides (NOx ) were consistently associated with increased risks of hypertension and triggering of myocardial infarction (MI), and stroke (fatal and nonfatal). Long-term exposures of PM2.5 were largely associated with increased risk of atherosclerosis, incident MI, hypertension, and incident stroke and stroke mortality. Few reviews evaluated other CVD outcomes including arrhythmias, atrial fibrillation, or heart failure but they generally reported positive statistical associations. Stronger associations were found in Asian countries and vulnerable subpopulations, especially among the elderly, cardiac patients, and people with higher weight status. Consistent with experimental data, this comprehensive umbrella review found strong evidence that higher levels of ambient air pollution increase the risk of CVDs, especially all-cause CVD mortality, stroke, and IHD. These results emphasize the importance of reducing the alarming levels of air pollution across the globe, especially in Asia, and among vulnerable subpopulations.

Public justification and expert disagreement over non-pharmaceutical interventions for the COVID-19 pandemic.

A wide range of non-pharmaceutical interventions (NPIs) have been introduced to stop or slow down the COVID-19 pandemic. Examples include school closures, environmental cleaning and disinfection, mask mandates, restrictions on freedom of assembly and lockdowns. These NPIs depend on coercion for their effectiveness, either directly or indirectly. A widely held view is that coercive policies need to be publicly justified-justified to each citizen-to be legitimate. Standardly, this is thought to entail that there is a scientific consensus on the factual propositions that are used to support the policies. In this paper, we argue that such a consensus has been lacking on the factual propositions justifying most NPIs. Consequently, they would on the standard view be illegitimate. This is regrettable since there are good reasons for granting the state the legitimate authority to enact NPIs under conditions of uncertainty. The upshot of our argument is that it is impossible to have both the standard interpretation of the permissibility of empirical claims in public justification and an effective pandemic response. We provide an alternative view that allows the state sufficient room for action while precluding the possibility of it acting without empirical support.

Building capacity for air pollution epidemiology in India.

Air pollution represents a major public health threat in India affecting 19% of the world's population at extreme levels. Despite this, research in India lags behind in large part due to a lack of comprehensive air pollution exposure assessment that can be used in conjunction with health data to investigate health effects. Our vision is to provide a consortium to rapidly expand the evidence base of the multiple effects of ambient air pollution. We intend to leapfrog current limitations of exposure assessment by developing a machine-learned satellite-informed spatiotemporal model to estimate daily levels of ambient fine particulate matter measuring less than 2.5 µm (PM2.5) at a fine spatial scale across all of India. To catalyze health effects research on an unprecedented scale, we will make the output from this model publicly available. In addition, we will also apply these PM2.5 estimates to study the health outcomes of greatest public health importance in India, including cardiovascular diseases, chronic obstructive pulmonary disease, pregnancy (and birth) outcomes, and cognitive development and/or decline. Thus, our efforts will directly generate actionable new evidence on the myriad effects of air pollution on health that can inform policy decisions, while providing a comprehensive and publicly available resource for future studies on both exposure and health effects. In this commentary, we discuss the motivation, rationale, and vision for our consortium and a path forward for reducing the enormous burden of disease from air pollution in India.

Short-term associations between ambient air pollution and acute atrial fibrillation episodes.

INTRODUCTION: Atrial fibrillation (AF), prevalent in approximately 1-3% of the population, is associated with a higher risk of stroke, dementia, mortality, and a reduced quality of life. Air pollution may be associated with heart rhythm disturbances, but there is limited evidence regarding whether short-term changes in air pollution levels are associated with acute onset of AF episodes. METHODS: We screened 8,899 randomly selected 75-yearolds living in Stockholm without previously known AF for AF using home-based short-term ambulatory 1-lead ECG-measurements 2-4 times a day for 14 days. Screenings were carried out in 2012-2013 and 2016-2018. We used generalized estimating equations to quantify the association between PM2.5, PM10, NO2 and O3 obtained from a fixed monitoring station and risk of AF onset among participants with AF observed during the screening period, adjusting for temperature, relative humidity and temporal factors. We explored potential susceptible subgroups. RESULTS: Among 218 participants with 469 AF episodes we observed higher odds of AF following higher 24-hour mean levels of PM10 and O3, reaching statistical significance for PM10 levels averaged over the previous 12-24-hours [OR 1.10 (95%CI 1.01-1.19) per IQR of PM10 (7.8 µg/m3)]. In subgroup analyses, PM2.5 was more strongly associated with AF among participants with hypertension and PM10 and O3 were more strongly associated with AF among participants with diabetes and overweight. CONCLUSION: These results suggest that in an urban setting with relatively low levels of ambient air pollution, hourly changes in pollutant levels may increase the risk of acute episodes of both asymptomatic and symptomatic AF, especially among people with diabetes, hypertension or overweight.

Ozone and cardiac arrest: The role of previous hospitalizations.

BACKGROUND: Several studies have reported associations between exposure to particulate matter and incidence of out-of-hospital cardiac arrest (OHCA) and some have observed associations with ozone (O3). There are no studies investigating susceptibility based on previous disease history to short-term O3 exposure and the risk of OHCA. AIM: To investigate the role of previous cardiovascular-related hospitalizations in modifying the associations between the risk of OHCA and short-term increase in O3 concentrations. METHODS: A time-stratified case-crossover analysis of 11,923 OHCA registered in the Swedish Register for Cardiopulmonary Resuscitation from 2006 to 2014 was performed. Using personal identification numbers, OHCA were linked to all previous hospitalizations in Sweden since 1987 to create susceptible groups based on the principal diagnosis code at discharge. Susceptibility was based on hospitalization for i) acute myocardial infarction; ii) heart failure; iii) arrhythmias; iv) diabetes; v) hypertension; and vi) stroke. Moving 2 and 24-h averages for O3, PM2.5, PM10, and NO2 were constructed from hourly averages. RESULTS: A 10 µg/m3 higher 2-h average O3 concentration was associated with a 2% higher risk of OHCA (95% CI, 0% 3%). Associations were similar for 24-h average O3 and in individuals with or without hospitalizations for AMI, heart failure, diabetes, hypertension or stroke. Individuals with previous hospitalizations for arrhythmias had a lower risk of OHCA with higher O3. No associations were observed for other pollutants. CONCLUSIONS: Short-term exposure to O3 was associated with an elevated risk of OHCA, however, previous hospitalizations for cardiovascular diseases were not associated with additionally augmented risks.

Susceptibility to short-term ozone exposure and cardiovascular and respiratory mortality by previous hospitalizations.

BACKGROUND: Ozone (O3) has been associated with cardiorespiratory mortality although few studies have explored susceptible populations based on prior disease. We aimed to investigate the role of previous hospitalization on the association between short-term exposure to O3 and cardiovascular (CV) and respiratory mortality. METHODS: We performed time series analyses using generalized additive models and case-crossover on 136,624 CV and 23,281 respiratory deaths in Stockholm County (1990-2010). Deaths were linked to hospital admissions data. We constructed 2-day and 7-day averages using daily 8-h maximum for O3 and hourly values for PM2.5, PM10, NO2, and NOx from a fixed monitor. RESULTS: We observed a 0.7% (95% CI: 0.1%, 1.3%) and 2.7% (95% CI: 0.8%, 4.6%) higher risk of CV and respiratory death per 10 µg/m3 higher 2-day and 7-day average O3 respectively. Individuals previously hospitalized for myocardial infarction demonstrated 1.8% (95% CI: 0.4%, 3.4%) higher risk of CV death per 10 µg/m3 higher 2-day average O3 and similar associations were observed in individuals with no previous hospitalization for any cause. Individuals with previous hospitalizations did not show susceptibility towards O3-related risk of respiratory mortality. We observed no associations for other pollutants. CONCLUSION: Short-term ozone exposure is associated with CV and respiratory mortality and our results may suggest higher susceptibility to CV mortality following O3 exposure in individuals previously hospitalized for myocardial infarction. Higher risks were also observed in individuals with cardiovascular death as their first presentation of disease.

Short-term departures from an optimum ambient temperature are associated with increased risk of out-of-hospital cardiac arrest.

BACKGROUND: Associations have been reported between daily ambient temperature and all-cause and cardiovascular mortality. However, the potential harmful effect of temperature on out-of-hospital cardiac arrest (OHCA) is insufficiently studied. OBJECTIVES: The objective of this study was to investigate the short-term association between ambient temperature and the occurrence of OHCA. METHODS: In 5961 cases of OHCAs treated by Emergency Medical Service occurring in Stockholm County we investigated the association between the preceding 24-h and 1h mean ambient temperature, obtained from a fixed monitoring station, and OHCA using a time-stratified case-crossover design. RESULTS: We observed a V-shaped relationship between preceding mean 24-h and 1-h ambient temperature and the occurrence of OHCAs. For mean 24-h temperature we observed an odds ratio (OR) of 1.05 (1.00-1.11) for each 5°C below the optimum temperature and 1.05 (0.96-1.18) for each 5°C above the optimum. We observed similar results for 1-h mean temperature exposure. Results for temperatures above the optimum temperature showed evidence of confounding by ozone. CONCLUSION: Ambient temperature below an optimum temperature was associated with increased risk of OHCA in Stockholm. Temperature above an optimum temperature was not significantly associated with OHCA.

Short-term effects of air pollution on out-of-hospital cardiac arrest in Stockholm.

BACKGROUND: Although ozone (O3) and other pollutants have been associated with cardiovascular morbidity and mortality, the effects of O3 on out-of-hospital cardiac arrest (OHCA) have rarely been addressed and existing studies have presented inconsistent findings. The objective of this study was to determine the effects of short-term exposure to air pollution including O3 on the occurrence of OHCA, and assess effect modification by season, age, and gender. METHODS AND RESULTS: A total of 5973 Emergency Medical Service-assessed OHCA cases in Stockholm County 2000-10 were obtained from the Swedish cardiac arrest register. A time-stratified case-crossover design was used to analyse exposure to air pollution and the risk of OHCA. Exposure to O3, PM2.5, PM10, NO2, and NOx was defined as the mean urban background level during 0-2, 0-24, and 0-72 h before the event and control time points. We adjusted for temperature and relative humidity. Ozone in urban background was associated with an increased risk of OHCA for all time windows. The respective odds ratio (confidence interval) for a 10 µg/m(3) increase was 1.02 (1.01-1.05) for a 2-h window, 1.04 (1.01-1.07) for 24-h, and 1.05 (1.01-1.09) for 3 day. The association with 2-h O3 was stronger for events that occurred outdoors: 1.13 (1.06-1.21). We observed no effects for other pollutants and no effect modification by age, gender, or season. CONCLUSION: Short-term exposure to moderate levels of O3 is associated with an increased risk of OHCA.