Air Pollution Linked to High Blood Pressure in Children; Other Studies Address Air Quality and the Heart

A meta-analysis of 14 air pollution studies from around the world found that exposure to high levels of air pollutants during childhood increases the likelihood of high blood pressure in children and adolescents, and their risk for high blood pressure as adults. The study is published in a special issue on air pollution in the Journal of the American Heart Association, an open access journal of the American Heart Association.

Other studies look at: the effects of diesel exhaust on the muscle sympathetic nerve; the impact of pollutants on high blood pressure; rates of hospital readmission for heart failure among those exposed to high levels of ambient air pollution; and risk of stroke and heart attack after long-term exposure to high levels of particulate matter. The studies include health outcomes of people who were exposed to pollutants in the United States, China and Europe.

High blood pressure during childhood and adolescence is a risk factor for hypertension and heart disease in adulthood. Studies on air pollution and blood pressure in adolescents and children, however, have produced inconsistent conclusions. This systematic review and meta-analysis pooled information from 14 studies focused on the association between air pollution and blood pressure in youth. The large analysis included data for more than 350,000 children and adolescents (mean ages 5.4 to 12.7 years of age).

“Our analysis is the first to closely examine previous research to assess both the quality and magnitude of the associations between air pollution and blood pressure values among children and adolescents,” said lead study author Yao Lu, M.D., Ph.D., professor of the Clinical Research Center at the Third Xiangya Hospital at Central South University in Changsha, China, and professor in the department of life science and medicine at King’s College London. “The findings provide evidence of a positive association between short- and long-term exposure to certain environmental air pollutants and blood pressure in children and adolescents.”

The analysis included 14 studies published through September 6, 2020, exploring the impact of long-term exposure (≥30 days) and/or short-term exposure (<30 days) of ambient air pollution on blood pressure levels of adolescents and/or children in China and/or countries in Europe.

The studies were divided into groups based upon length of exposure to air pollution and by composition of air pollutants, specifically nitrogen dioxide and particulate matter with diameter ≤10 μm or ≤2.5 μm. (The majority of research linking heart disease with particulate matter focuses on particle matter mass, which is categorized by aerodynamic diameter – μm or PM.) Fine particles are defined as PM2.5 and larger; coarse particles are defined at PM10; and the concentrations of particulate matter are typically measured in their mass per volume of air (μg/m3).

The meta-analysis concluded:

  • Short-term exposure to PM10 was significantly associated with elevated systolic blood pressure in youth (the top number on a blood pressure reading).
  • Periods of long-term exposure to PM2.5, PM10 and nitrogen dioxide were also associated with elevated systolic blood pressure levels.
  • Higher diastolic blood pressure levels (the bottom number on a blood pressure reading) were associated with long-term exposure to PM2.5 and PM10.

“To reduce the impact of environmental pollution on blood pressure in children and adolescents, efforts should be made to reduce their exposure to environmental pollutants,” said Lu. “Additionally, it is also very important to routinely measure blood pressure in children and adolescents, which can help us identify individuals with elevated blood pressure early.”

The results of the analysis are limited to the studies included, and they did not include data on possible interactions between different pollutants, therefore, the results are not generalizable to all populations. Additionally, the analysis included the most common and more widely studied pollutants vs. air pollutants confirmed to have heart health impact, of which there are fewer studies.

Source: American Heart Association

Long-term Exposure to Low Levels of Air Pollution Increases Risk of Heart and Lung Disease

Exposure to what is considered low levels of air pollution over a long period of time can increase the risk of heart attack, stroke, atrial fibrillation and pneumonia among people ages 65 and older, according to new research published today in the American Heart Association’s flagship journal Circulation.

Air pollution can cause harm to the cardiovascular and respiratory systems due to its effect on inflammation in the heart and throughout the body. Newer studies on the impact of air pollution on health are focused on understanding the potential harm caused by long-term exposure and are researching the effects of multiple air pollutants simultaneously. Research on air pollution is critical to informing recommendations for national environmental and health guidelines.

“People should be conscious of the air quality in the region where they live to avoid harmful exposure over long periods of time, if possible,” said Mahdieh Danesh Yazdi, Pharm.D., M.P.H., Ph.D., a post-doctoral research fellow at the Harvard T.H. Chan School of Public Health and lead author of the study. “Since our study found harmful effects at levels below current U.S. standards, air pollution should be considered as a risk factor for cardiovascular and respiratory disease by clinicians, and policy makers should reconsider current standards for air pollutants.”

Researchers examined hospitalization records for more than 63 million Medicare enrollees in the contiguous Unites States from 2000 to 2016 to assess how long-term exposure to air pollution impacts hospital admissions for specific cardiovascular and respiratory issues. The study measured three components of air pollution: fine particulate matter (PM2.5), nitrogen dioxide (NO2) and ozone (O3). Using hundreds of predictors, including meteorological values, satellite measurements and land use to estimate daily levels of pollutants, researchers calculated the study participants’ exposure to the pollutants based upon their residential zip code. Additional analysis included the impact of the average yearly amounts of each of the pollutants on hospitalization rates for non-fatal heart attacks, ischemic strokes, atrial fibrillation and flutter, and pneumonia.

Statistical analyses found thousands of hospital admissions were attributable to air pollution per year. Specifically:

  • The risks for heart attacks, strokes, atrial fibrillation and flutter, and pneumonia were associated with long-term exposure to particulate matter.
  • Data also showed there were surges in hospital admissions for all of the health outcomes studied with each additional unit of increase in particulate matter. Specifically, stroke rates increased by 2,536 for each additional ug/m3 (micrograms per cubic meter of air) increase in fine particulate matter each year.
  • There was an increased risk of stroke and atrial fibrillation associated with long-term exposure to nitrogen dioxide.
  • Pneumonia was the only health outcome in the study that seemed impacted by long-term exposure to ozone; however, researchers note there are currently no national guidelines denoting safe or unsafe long-term ozone levels.

“When we restricted our analyses to individuals who were only exposed to lower concentrations of air pollution, we still found increased risk of hospital admissions with all of the studied outcomes, even at concentration levels below current national standards,” added Danesh Yazdi. “More than half of the study population is exposed to low levels of these pollutants, according to U.S. benchmarks, therefore, the long-term health impact of these pollutants should be a serious concern for all, including policymakers, clinicians and patients.”

The researchers further stratified the analyses to calculate the cardiovascular and respiratory risks associated with each of the pollutants among patient subgroups including gender, race or ethnicity, age and socioeconomic factors, detailed in the study.

The causality in the study could only be interpreted and not proven definitively due to the limitations of the data available, which may have not included other known CVD risk factors. In addition, coding errors can occur in the Medicare database, which would impact the analyses.

Source: American Heart Association

Study: How Air Pollution May Increase the Risk of Cardiovascular Disease

Julie Cunningham wrote . . . . . . . . .

Tiny particles of air pollution — called fine particulate matter — can have a range of effects on health, and exposure to high levels is a known risk factor for cardiovascular disease. New research led by investigators at Massachusetts General Hospital (MGH) reveals that fine particulate matter has a detrimental impact on cardiovascular health by activating the production of inflammatory cells in the bone marrow, ultimately leading to inflammation of the arteries. The findings are published in the European Heart Journal.

The retrospective study included 503 patients without cardiovascular disease or cancer who had undergone imaging tests at MGH for various medical reasons. The scientists estimated participants’ annual average fine particulate matter levels using data obtained from the U.S. Environment Protection Agency’s air quality monitors located closest to each participant’s residential address.

Over a median follow-up of 4.1 years, 40 individuals experienced major cardiovascular events, such as heart attacks and strokes, with the highest risk seen in participants with higher levels of fine particulate matter at their home address. Their risk was elevated even after accounting for cardiovascular risk factors, socioeconomic factors, and other key confounders. Imaging tests assessing the state of internal organs and tissues showed that these participants also had higher bone marrow activity, indicating a heightened production of inflammatory cells (a process called leukopoiesis), and elevated inflammation of the arteries. Additional analyses revealed that leukopoiesis in response to air pollution exposure is a trigger that causes arterial inflammation.

“The pathway linking air pollution exposure to cardiovascular events through higher bone marrow activity and arterial inflammation accounted for 29% of the relationship between air pollution and cardiovascular disease events,” says co–first author Shady Abohashem, MD, a cardiovascular imaging fellow at MGH. “These findings implicate air pollution exposure as an underrecognized risk factor for cardiovascular disease and suggest therapeutic targets beyond pollution mitigation to lessen the cardiovascular impact of air pollution exposure.”

Co–first author Michael Osborne, MD, a cardiologist at MGH, explains that therapies targeting increased inflammation following exposure to fine particulate matter may benefit patients who cannot avoid air pollution. “Importantly, most of the population studied had air pollution exposures well below the unhealthy thresholds established by the World Health Organization, suggesting that no level of air pollution can truly be considered safe,” he says.

Source: Massachusetts General Hospital

Leading Cardiovascular Organizations Call for Urgent Action to Reduce Air Pollution

Air pollution is a key risk factor for cardiovascular disease, and a major contributor to the global burden of disease. Long-term exposure to air pollution has also been linked to an increased risk of death from COVID-19. This dangerous “triple threat” of air pollution, COVID-19 and cardiovascular disease should be taken seriously, warn major health authorities.

Four leading cardiovascular organizations – the World Heart Federation (WHF), American College of Cardiology (ACC), American Heart Association (AHA) and European Society of Cardiology (ESC) – today released a joint statement urging the medical community and health authorities to mitigate the impact of air pollution on people’s health.

In 2019, an estimated 6.7 million deaths, or 12 percent of all deaths worldwide, were attributable to outdoor or household air pollution. As many as half of these were due to cardiovascular disease. Air pollution also increases the risk of heart attack, stroke, diabetes and respiratory diseases, which are known to raise a person’s risk of experiencing some of the more severe consequences of COVID-19.

“Even before the COVID-19 pandemic, air pollution was an issue of growing concern due to its impact on people’s health, although it was frequently overlooked as a risk factor for cardiovascular disease. COVID-19 has brought a new, deadly factor to the equation, and the time has come for the health community to speak up and take action,” said Michael Brauer, Chair of the World Heart Federation Air Pollution Expert Group and co-author of the statement.

The statement calls for structural actions to reduce emissions of air pollutants and harmful exposure. It also highlights the important role that healthcare providers play in preventing illnesses related to air pollution, including:

  • Advocating for air pollution mitigation as a health measure, further research on air quality and its impact on CVD, and interventions to reduce air pollution and its effect on NCDs
  • Providing patients with personal measures to reduce exposure, such as room air filtration systems
  • Integrating air pollution into disease management approaches, for example through the use of air quality indices
  • Participating in the development of guidelines on air pollution and CVD
  • Supporting ministries of environment, energy, and transportation in their mitigation efforts
  • Working to educate and raise awareness on the cardiovascular benefits of clean air
  • Collaborating with senior decision-makers in national, regional, and global governmental institutions to make air pollution related heart disease a priority

The statement will be published simultaneously in the flagship journals of all four organizations: the Journal of the American College of Cardiology (JACC), the Journal of the American Heart Association (JAHA), the European Heart Journal (EHJ) and Global Heart.

* * * * * * * * *

“Clinicians have a responsibility to educate their patients, their colleagues and their communities at large on the connection between air pollution and cardiovascular disease risk,” said Richard Kovacs, MD, MACC, senior author of the joint statement and ACC Immediate Past President. “By advocating for recognition of air pollution as a health factor, working individually with our patients to reduce exposure and associated risks, and integrating air pollution into broader disease management approaches, the health care community can provide support for larger pollution mitigation efforts.”

“Poor air quality can harm heart and brain health, with a disproportionate impact on low-income and poor communities located near sources of air pollution,” said Robert Harrington, M.D., FAHA, Arthur L. Bloomfield Professor of Medicine and Chair of the Department of Medicine at Stanford University, Immediate Past President of the American Heart Association and a co-author of the statement. “We must address this problem as a global community to equitably reduce exposure to air pollution and reverse the health harms of poor air quality for all.”

“Air pollution is one of the most underestimated causes of heart disease and stroke,” said Professor Stephan Achenbach, President of the European Society of Cardiology. “More research is urgently required to identify susceptible populations and to determine the optimal methods of improving air quality to benefit cardiovascular health. Air pollution needs to be recognized as a major modifiable risk factor in the prevention and management of cardiovascular disease, and measures to reduce its detrimental short-term and long-term influence on cardiovascular health, potentially over generations, are urgently required.”

Source: American Heart Association

Air Pollution Linked to Higher Risk of Sight Loss from AMD

They found that people in the most polluted areas were at least 8% more likely to report having AMD, according to the findings published in the British Journal of Ophthalmology.

Lead author Professor Paul Foster (UCL Institute of Ophthalmology) said: “Here we have identified yet another health risk posed by air pollution, strengthening the evidence that improving the air we breathe should be a key public health priority. Our findings suggest that living in an area with polluted air, particularly fine particulate matter or combustion-related particles that come from road traffic, could contribute to eye disease.

“Even relatively low exposure to air pollution appears to impact the risk of AMD, suggesting that air pollution is an important modifiable risk factor affecting risk of eye disease for a very large number of people.”

AMD is the leading cause of irreversible blindness among people over 50 in high-income countries, with the numbers of those affected projected to reach 300 million by 2040. Known risk factors include older age, smoking, and genetic make-up.

Air pollution has been implicated in brain conditions such as Alzheimer’s disease, Parkinson’s disease and stroke, while a 2019 study by the same research team found that air pollution was linked to elevated glaucoma risk.* Particulate matter exposure is one of the strongest predictors of mortality among air pollutants.

To see if air pollution might also be implicated in AMD risk, the researchers drew on data from 115,954 UK Biobank study participants aged 40-69 with no eye problems at the start of this study in 2006.

Participants were asked to report any formal diagnosis of AMD by a doctor. And structural changes in the thickness and/or numbers of light receptors in the retina – indicative of AMD – were assessed in 52,602 of the participants, for whom complete data were available in 2009 and 2012, using retinal imaging (non-invasive optical coherence tomography or OCT).

Measures of ambient air pollution included those for particulate matter (PM2.5), nitrogen dioxide (NO2), and nitrogen oxides (NOx). The estimates for these were provided by the Small Area Health Statistics Unit as part of the BioSHaRE-EU Environmental Determinants of Health Project. Official information on traffic, land use, and topography was used to calculate the annual average air pollution levels at participants’ home addresses.

The research team found that people in areas with higher levels of fine particulate matter pollution were more likely to report having AMD (specifically, they found an 8% difference in AMD risk between people living in the 25th and 75th percentiles of pollution levels), after accounting for potentially influential factors such as underlying health conditions and lifestyle. All pollutants, except coarse particulate matter, were associated with changes in retinal structure.

The researchers caution that this observational study cannot confirm cause, but their findings align with evidence from elsewhere in the world.

While they cannot yet confirm a mechanism, they suggest that ambient air pollution could plausibly be associated with AMD through oxidative stress or inflammation.

Dr Sharon Chua (UCL Institute of Ophthalmology), the paper’s first author, adds: “Higher exposure to air pollution was also associated with structural features of AMD. This may indicate that higher levels of air pollution may cause the cells to be more vulnerable to adverse changes and increase the risk of AMD.”

Source: University College London