Increased resting heart rate with pollutants in a population based study

Association Between Nitrogen Dioxide Pollution and Cause-Specific Mortality in China: Cross-Sectional Time Series Study

BACKGROUND

Nitrogen dioxide (NO2) has been frequently linked to a range of diseases and associated with high rates of mortality and morbidity worldwide. However, there is limited evidence regarding the risk of NO2 on a spectrum of causes of mortality. Moreover, adjustment for potential confounders in NO2 analysis has been insufficient, and the spatial resolution of exposure assessment has been limited.

OBJECTIVE

This study aimed to quantitatively assess the relationship between short-term NO2 exposure and death from a range of causes by adjusting for potential confounders in Guangzhou, China, and determine the modifying effect of gender and age.

METHODS

A time series study was conducted on 413,703 deaths that occurred in Guangzhou during the period of 2010 to 2018. The causes of death were classified into 10 categories and 26 subcategories. We utilized a generalized additive model with quasi-Poisson regression analysis using a natural cubic splines function with lag structure of 0 to 4 days to estimate the potential lag effect of NO2 on cause-specific mortality. We estimated the percentage change in cause-specific mortality rates per 10 μg/m3 increase in NO2 levels. We stratified meteorological factors such as temperature, humidity, wind speed, and air pressure into high and low levels with the median as the critical value and analyzed the effects of NO2 on various death-causing diseases at those high and low levels. To further identify potentially vulnerable subpopulations, we analyzed groups stratified by gender and age.

RESULTS

A significant association existed between NO2 exposure and deaths from multiple causes. Each 10 μg/m3 increment in NO2 density at a lag of 0 to 4 days increased the risks of all-cause mortality by 1.73% (95% CI 1.36%-2.09%) and mortality due to nonaccidental causes, cardiovascular disease, respiratory disease, endocrine disease, and neoplasms by 1.75% (95% CI 1.38%-2.12%), 2.06% (95% CI 1.54%-2.59%), 2.32% (95% CI 1.51%-3.13%), 2.40% (95% CI 0.84%-3.98%), and 1.18% (95% CI 0.59%-1.78%), respectively. Among the 26 subcategories, mortality risk was associated with 16, including intentional self-harm, hypertensive disease, and ischemic stroke disease. Relatively higher effect estimates of NO2 on mortality existed for low levels of temperature, relative humidity, wind speed, and air pressure than with high levels, except a relatively higher effect estimate was present for endocrine disease at a high air pressure level. Most of the differences between subgroups were not statistically significant. The effect estimates for NO2 were similar by gender. There were significant differences between the age groups for mortality due to all causes, nonaccidental causes, and cardiovascular disease.

CONCLUSIONS

Short-term NO2 exposure may increase the risk of mortality due to a spectrum of causes, especially in potentially vulnerable populations. These findings may be important for predicting and modifying guidelines for NO2 exposure in China.

High blood pressure and exposure to dust from gold mine dumps among the elderly in South Africa: A cross-sectional study

Objective

To investigate whether high blood pressure was associated with living close to a mine dump among the elderly in South Africa.

Study design

This was a cross-sectional study conducted among the elderly in communities 1–2 km (exposed) and 5 km or more (unexposed), from five pre-selected mine dumps in Gauteng and North West provinces of South Africa.

Methods

Structured interviews were conducted with 2397 elderly, using a previously validated ATS-DLD-78 questionnaire from the British Medical Research Council.

Results

The prevalence of high blood pressure was 57.51% in the exposed and 46.66% in the unexposed communities, respectively. Results from the multiple logistic regression analysis showed that having high blood pressure was significantly associated with living in exposed communities (AOR = 3.04, 95% CI: 2.41–3.83, P < 0.001). Other significant risk factors were being an previous and current tobacco smoker, age group, tertiary level of educational attainment, and having a history of occupational exposure to dust and chemical fumes.

Conclusion

The findings of this study suggest that there are high levels of blood pressure among the elderly residing in communities located near mine dumps in South Africa.

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There was a high prevalence of high blood pressure among the elderly living close to gold mine dumps in South Africa.

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There was a statistically significant association between community proximity to gold mine dumps and high blood pressure.

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Unrehabilitated mine dumps are a public threat.

Association between Air Pollutants and Initial Hospital Admission for Ischemic Stroke in Korea from 2002 to 2013

OBJECTIVES

There is limited information regarding the association between air pollution exposure and stroke incidence. Therefore, this study aimed to assess the associations between short-term exposure to ambient air pollutants and initial hospital admission for ischemic stroke.

MATERIALS AND METHODS

From the Korea National Health Insurance Service-National Sample Cohort 2002-2013 database in South Korea, 55,852 first hospital admissions for ischemic stroke were identified. A generalized additive Poisson model was used to explore the association between air pollutants, including particulate matter, sulfur dioxide, nitrogen dioxide, and carbon monoxide and admissions for ischemic stroke.

RESULTS

All air pollutant models showed significant associations with ischemic stroke in the single lag model. In all air pollutant models excluding particulate matter 10 μm, a significant association was found between nitrogen dioxide exposure and initial admission for ischemic stroke after adjusting for other pollutants. An increment of 10 μg/m³ in nitrogen dioxide concentration at lag 0 and 14 days corresponded to a 0.259% (95% confidence interval, 0.231-0.287%) and 0.110% (95% confidence interval, 0.097-0.124) increase in initial admission for ischemic stroke, respectively.

CONCLUSIONS

The exposure-response relationship between nitrogen dioxide and initial admissions for ischemic stroke was approximately linear, with a sharper response at higher concentrations. Short-term exposure to nitrogen dioxide was positively associated with initial hospital admission for ischemic stroke.

Short-term effects of nitrogen dioxide on hospital admissions for cardiovascular disease in Wallonia, Belgium

Many studies have shown a short-term association between NO₂ and cardiovascular disease. However, few data are available on the delay between exposure and a health-related event. The aim of the present study is to determine the strength of association between NO₂ and cardiovascular health in Wallonia for the period 2008-2011. This study also seeks to evaluate the effects of age, gender, season and temperature on this association. The effect of the delay between exposure and health-related event was also investigated. The daily numbers of hospital admissions for arrhythmia, acute myocardial infarction, ischemic and haemorrhagic stroke were taken from a register kept by Belgian hospitals. Analyses were performed using the quasi-Poisson regression model adjusted for seasonality, long-term trend, day of the week, and temperature. Our study confirms the existence of an association between NO₂ and cardiovascular disease. Apart from haemorrhagic stroke, the strongest association between NO₂ concentrations and number of hospital admissions is observed at lag 0. For haemorrhagic stroke, the association is strongest with a delay of 2days. All associations calculated without stratification are statistically significant and range from an excess relative risk of 2.8% for myocardial infarction to 4.9% for haemorrhagic strokes. The results of this study reinforce the evidence of the short-term effects of NO₂ on hospital admissions for cardiovascular disease. The different delay between exposure and health-related event for haemorrhagic stroke compared to ischemic stroke suggests different mechanisms of action.

Weight-of-evidence evaluation of short-term ozone exposure and cardiovascular effects

There is a relatively large body of research on the potential cardiovascular (CV) effects associated with short-term ozone exposure (defined by EPA as less than 30 days in duration). We conducted a weight-of-evidence (WoE) analysis to assess whether it supports a causal relationship using a novel WoE framework adapted from the US EPA's National Ambient Air Quality Standards causality framework. Specifically, we synthesized and critically evaluated the relevant epidemiology, controlled human exposure, and experimental animal data and made a causal determination using the same categories proposed by the Institute of Medicine report Improving the Presumptive Disability Decision-making Process for Veterans ( IOM 2008). We found that the totality of the data indicates that the results for CV effects are largely null across human and experimental animal studies. The few statistically significant associations reported in epidemiology studies of CV morbidity and mortality are very small in magnitude and likely attributable to confounding, bias, or chance. In experimental animal studies, the reported statistically significant effects at high exposures are not observed at lower exposures and thus not likely relevant to current ambient ozone exposures in humans. The available data also do not support a biologically plausible mechanism for CV effects of ozone. Overall, the current WoE provides no convincing case for a causal relationship between short-term exposure to ambient ozone and adverse effects on the CV system in humans, but the limitations of the available studies preclude definitive conclusions regarding a lack of causation. Thus, we categorize the strength of evidence for a causal relationship between short-term exposure to ozone and CV effects as "below equipoise."

Controlled exposure of healthy young volunteers to ozone causes cardiovascular effects

BACKGROUND

Recent epidemiology studies have reported associations between short-term ozone exposure and mortality. Such studies have previously reported associations between airborne particulate matter pollution and mortality, and support for a causal relationship has come from controlled-exposure studies that describe pathophysiological mechanisms by which particulate matter could induce acute mortality. In contrast, for ozone, almost no controlled-human-exposure studies have tested whether ozone exposure can modulate the cardiovascular system.

METHODS AND RESULTS

Twenty-three young healthy individuals were exposed in a randomized crossover fashion to clean air and to 0.3-ppm ozone for 2 hours while intermittently exercising. Blood was obtained immediately before exposure, immediately afterward, and the next morning. Continuous Holter monitoring began immediately before exposure and continued for 24 hours. Lung function was performed immediately before and immediately after exposure, and bronchoalveolar lavage was performed 24 hours after exposure. Immediately after ozone exposure, we observed a 98.9% increase in interleukin-8, a 21.4% decrease in plasminogen activator inhibitor-1, a 51.3% decrease in the high-frequency component of heart rate variability, and a 1.2% increase in QT duration. Changes in interleukin-1B and plasminogen activator inhibitor-1 were apparent 24 hours after exposure. In agreement with previous studies, we also observed ozone-induced drops in lung function and an increase in pulmonary inflammation.

CONCLUSIONS

This controlled-human-exposure study shows that ozone can cause an increase in vascular markers of inflammation and changes in markers of fibrinolysis and markers that affect autonomic control of heart rate and repolarization. We believe that these findings provide biological plausibility for the epidemiology studies that associate ozone exposure with mortality.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01492517.

Gender-specific trends in heart rate in the general population from 1992-2007: a study of 226,288 French adults

OBJECTIVES

Heart rate (HR) has been associated with cardiovascular (CV) risk factors and with CV mortality. Trends in CV risk factors have been described in recent decades, but HR changes over time have been less studied. We thus aimed to examine the secular trends in HR and interrelationships between HR and traditional CV risk factors and mortality.

METHODS

We studied 226,288 consecutive participants (141,533 men and 84,755 women) aged 44.7 ± 12.7 years who had a free standard health check up, between 1992 and 2007. Each had resting HR measured systematically on a 10-cycle electrocardiogram, and assessment of lipoproteins, blood pressure, smoking, glycemic status, body mass index, and physical activity. Sex-specific trends in mean HR were estimated by a general linear model adjusted for traditional CV risk factors and CV treatment. In that model, year was considered as a continuous variable.

RESULTS

Crude mean HR decreased over the study period (from 68.9 ± 10.4 to 63.7 ± 9.0 beats/min in men; from 72.2 ± 10.3 to 65.2 ± 9.0 beats/min in women; p < 0.001 for both). The amplitude of the HR decrease was similar after full adjustment and across the pre-cited risk factors categories. On multivariate analysis, higher HR (≥ 80 beats/min vs. <60 beats/min) was associated with higher mortality rate over 5 years in men (hazard ratio 2.11, 95% CI 1.79-2.49) and women (hazard ratio 1.58, 95% CI 1.16-2.15).

CONCLUSION

In this large population-based study of 226,288 middle-aged participants, heart rate declined over 16 years independently of traditional CV risk factors.

Pulmonary ozone exposure induces vascular dysfunction, mitochondrial damage, and atherogenesis

More than 100 million people in the United States live in areas that exceed current ozone air quality standards. In addition to its known pulmonary effects, environmental ozone exposures have been associated with increased hospital admissions related to cardiovascular events, but to date, no studies have elucidated the potential molecular mechanisms that may account for exposure-related vascular impacts. Because of the known pulmonary redox and immune biology stemming from ozone exposure, we hypothesized that ozone inhalation would initiate oxidant stress, mitochondrial damage, and dysfunction within the vasculature. Accordingly, these factors were quantified in mice consequent to a cyclic, intermittent pattern of ozone or filtered air control exposure. Ozone significantly modulated vascular tone regulation and increased oxidant stress and mitochondrial DNA damage (mtDNA), which was accompanied by significantly decreased vascular endothelial nitric oxide synthase protein and indices of nitric oxide production. To examine influences on atherosclerotic lesion formation, apoE-/- mice were exposed as above, and aortic plaques were quantified. Exposure resulted in significantly increased atherogenesis compared with filtered air controls. Vascular mitochondrial damage was additionally quantified in ozone- and filtered air-exposed infant macaque monkeys. These studies revealed that ozone increased vascular mtDNA damage in nonhuman primates in a fashion consistent with known atherosclerotic lesion susceptibility in humans. Consequently, inhaled ozone, in the absence of other environmental toxicants, promotes increased vascular dysfunction, oxidative stress, mitochondrial damage, and atherogenesis.

Effects of nitrogen dioxide on human health: systematic review of experimental and epidemiological studies conducted between 2002 and 2006

In order to assess health effects in humans caused by environmental nitrogen dioxide (NO(2)) a systematic review of studies in humans was conducted. MEDLINE database was searched for epidemiological studies and experiments on adverse effects of NO(2) published between 2002 and 2006. The evidence with regard to NO(2) exposure limits was assessed using the Scottish Intercollegiate Guidelines Network (SIGN) grading system and the modified three star system. Of the 214 articles retrieved 112 fulfilled the inclusion criteria. There was limited evidence that short-term exposure to a 1-h mean value below 200 microg NO(2)/m(3) is associated with adverse health effects provided by only one study on mortality in patients with severe asthma (*2+). The effect remained after adjusting for other air pollutants. There was moderate evidence that short-term exposure below a 24-h mean value of 50 microg NO(2)/m(3) at monitor stations increases hospital admissions and mortality (**2+). Evidence was also moderate when the search was restricted to susceptible populations (children, adolescents, elderly, and asthmatics). There was moderate evidence that long-term exposure to an annual mean below 40 microg NO(2)/m(3) was associated with adverse health effects (respiratory symptoms/diseases, hospital admissions, mortality, and otitis media) provided by generally consistent findings in five well-conducted cohort and case-control studies with some shortcomings in the study quality (**2+). Evidence was also moderate when the search was restricted to studies in susceptible populations (children and adolescents) and for the combination with other air pollutants. The most frequent reasons for decreased study quality were potential misclassification of exposure and selection bias. None of the high-quality observational studies evaluated was informative for the key questions due to the choice of the dose parameter (e.g., 1-week mean) and exposure levels above the limit values. Inclusion of study designs unlisted in the SIGN grading system did not bring additional evidence regarding exposures below the current air quality limit values for NO(2). As several recent studies reported adverse health effects below the current exposure limits for NO(2) particularly among susceptible populations regarding long-term exposure further research is needed. Apart from high-quality epidemiological studies on causality and the interaction of NO(2) with other air pollutants there is a need for double-blinded randomized cross-over studies among susceptible populations for further evaluation of the short-term exposure limits.

Seasonal variation of effect of air pollution on blood pressure

BACKGROUND

Many studies have shown a consistent association between ambient air pollution and an increase in death due to cardiovascular causes. An increase in blood pressure is a common risk factor for a variety of cardiovascular diseases. However, the association between air pollution and blood pressure has not been evaluated extensively.

METHODS

In this cross-sectional study, we measured blood pressure in 10,459 subjects who had a health examination from 2001 to 2003, and calculated individual's exposure to ambient levels of air pollutants. To evaluate the relationship between exposure to air pollutants and blood pressure with respect to season, we performed a multiple regression analysis, separately, according to season, controlling for individual characteristics and meteorological variables.

RESULTS

In the warm-weather season (July-September), particulate air pollutant of <10 microm (PM(10)) and nitrogen dioxide (NO(2)) concentrations were significantly associated with measures of blood pressure. During cold weather (October-December), blood pressure was significantly associated with sulphur dioxide (SO(2)) and ozone (O(3)) concentrations. The significant association between PM(10) or NO(2) and blood pressure disappeared during the cold-weather season.

CONCLUSION

We found a seasonal variation for the association between ambient air-pollutant concentrations and blood pressure.