Category: Environmental Effects

Categories : Environmental EffectsTags :

Ozone Linked to Cognitive Impairment with Age

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A robust link has been established between long-term ozone exposure and an increased risk of cognitive impairment in older adults, according to a large-scale study published in Environment International.

Air pollution has long been considered a major risk factor for an ageing society. Fine airborne particulate matter can lead to dementia and other cognitive disabilities. But beyond airborne particles, little is known about the way in which other pollutants can pose a similar danger.

The researchers chose to focus on ambient ozone, a highly reactive gas that exists in much of smog at ground level. They then observed health outcomes in nearly 10 000 older adults across China and analysed the extent to which long-term ozone exposure may have impacted their cognitive ability over time.

The results, they found, were startling. For every 10 microgram increase of yearly average ozone exposure, the risk for cognitive impairment grew by more than 10%. Through their analysis, the researchers also found that this association held even when they abstracted away individual risk factors such as smoking, drinking and education level. That is, older adults in China who were exposed to high levels of yearly ozone pollution were more likely to develop cognitive disabilities later in life, no matter what other activities they were involved in.

“Our findings suggest potential benefits in delaying the progression of cognitive decline among older adults if ozone levels are reduced below the new WHO Global Air Quality Guideline for ozone pollution,” said Kai Chen, Ph.D., assistant professor at the Yale School of Public Health and the study’s lead author.

The researchers acknowledged limitations such as observational data being unable to establish a causal link. More research is needed into ozone’s destructive mechanism. And since many older adults in China spend more time indoors, their ozone exposure may be different.

Nonetheless, the findings match what other researchers have found in areas across the globe: Over the past several years, studies have traced a similar link in adults in the United States and in Taiwan, and have also found an association between ozone exposure and other neurological diseases.

The study shows that ozone exposure needs to be curbed worldwide to prevent healthcare systems from being overwhelmed as populations age and pollution increases.

Study co-author Professor Robert Dubrow said what makes this issue more urgent is that “ozone pollution is projected to be worsening under climate change.” Reducing this threat could bring significant benefits to public health and improve quality of life.

Source: Yale University

Categories : Environmental Effects Lab Tests and ImagingTags :

Lab Results are Influenced by Ambient Daily Temperatures

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Ambient temperature influences many common lab tests, and these distortions likely affect medical decision making, such as whether to prescribe medications, according to new research published in the journal Med. 

To account for this, the researchers suggest that laboratories could statistically adjust for ambient temperature on test days when reporting lab results.

“When a doctor orders a laboratory test, she uses it to shed light on what’s going on inside your body, but we wondered if the results of those tests could also reflect something that’s going on outside of your body” said study co-author Ziad Obermeyer of the University of California, Berkeley. “This is exactly the kind of pattern that doctors might miss. We’re not looking for it, and lab tests are noisy.”

Delving into this problem, Obermeyer and Devin Pope of the University of Chicago analysed a large dataset of test results from different climates. In a sample of more than four million patients, they modelled more than two million test results based on temperature. They measured how day-to-day temperature fluctuations influenced results, over and above the patients’ average values, and seasonal variation.

Temperature was found to affect more than 90% of individual tests and 51 of 75 assays, including measures of kidney function, cellular blood components, and lipids such as cholesterol and triglycerides. “It’s important to note that these changes were small: less than one percent differences in most tests under normal temperature conditions,” Obermeyer said.

These small fluctuations did not likely reflect long-term physiological trends. For example, lipid panels checked on cooler days appeared to suggest a lower cardiovascular risk, resulting in almost 10% fewer prescriptions for cholesterol-lowering drugs called statins to patients tested on the coolest days compared to the warmest days, despite the results likely not reflecting stable changes in cardiovascular risk.

Since the study wasn’t an experiment, the exact mechanisms underlying the fluctuations in lab results could not be pinpointed. However, blood volume, specific assay performance, specimen transport, or changes in lab equipment might explain them. “Whatever their cause, temperature produces undesirable variability in at least some tests, which in turn leads to distortions in important medical decisions,” Pope said.

Laboratories could get around this by statistically adjusting for ambient temperature on the test day when reporting lab results. This could be a way to reduce weather-related variability without expensive temperature control equipment. 

In practice, decisions on adjustment would need to be at the discretion of the laboratory staff and the treating physician, potentially on a case-by-case basis.

According to the authors, the study may also have broader clinical implications. “The textbook way of thinking about medical research is bench to bedside. First, we come up with a hypothesis, based on theory, then we test it with data,” Obermeyer said. “As more and more big data comes online, like the massive dataset of lab tests we used, we can flip that process on its head: discover fascinating new patterns and then use bench science to get to the bottom of it. I think this bedside-to-bench model is just as important as its better-known cousin because it can open up totally new questions in human physiology.”

Source: Science Daily

Categories : Environmental EffectsTags :

Extreme Heat Health Risks Are Higher for Younger Adults

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A new study in the US has found that complications from extreme heat appear to be more pronounced among young and middle-aged adults than older adults.

Extreme heat poses an increasing threat to the public, due to the continued effects of climate change. Although the adverse health impacts of heat have been well documented among older adults, less is known about the potential impacts of heat on young and middle-aged adults.

Published in the BMJ, the study examined the relationship between extreme temperatures and emergency department (ED) visits, and found that days of extreme heat were associated with an increase risk of ED visits for any cause, heat-related illness, renal disease, and mental disorders among all adults, but the strongest association was found among adults ages 18-64.

Prior research on heat’s health impacts have mostly focused on mortality or hospital admissions among seniors. This study is the first national-scale assessment of extreme heat effects on adults of all ages, measured with ED visits.

“Many illnesses that lead to utilisation of the ED do not lead to hospitalisation because they can be treated in a short amount of time, particularly among the younger adult population,” said study senior author Gregory Wellenius, professor of environmental health and director of the Program on Climate and Health at SPH. “By looking at emergency room visits, we aimed to obtain a more comprehensive picture of the true burden of disease that might be attributed to the days of high heat.”

Prof Wellenius and colleagues analysed healthcare claims data to quantify the risk of ED visits for any cause and for heat-associated conditions during the warm season (between May and September) from 2010 to 2019.

For the study, the researchers analysed claims data among 74 million adults, including more than 22 million ED visits. They found that days of extreme heat (varying by location, but averaging about 34°C), were associated with a 66% greater risk of ED visits for heat-related illness, as well as a 30% increased risk for renal disease, compared to ED visits on cooler days. But the risk according to extreme heat varied by age. A day of extreme heat was associated with a 10.3% higher risk of ED visits among people ages 45 to 54 years old, compared to a 3.6% higher risk among those older than 75.

“Younger adults may be at greater risk of exposure to extreme heat, particularly among workers that spend substantial time outdoors,” says study lead author Shengzhi Sun, research scientist in the Department of Environmental Health at SPH. “Younger adults may also not realise that they too can be at risk on days of extreme heat.”

Prior studies had shown that people in US counties with lower warm-season temperatures still experience higher risks of heat-related complications.
“While extreme heat threatens everyone’s health, this study provides further evidence that it is especially dangerous in regions with cooler climates that may be less adapted to heat,” says study co-author Kate Weinberger, assistant professor at the University of British Columbia’s School of Population and Public Health. “As temperatures continue to rise due to climate change, the implementation of heat adaptation measures in these regions will be critically important.”

According to the researchers, many of these heat-related complications can be prevented through policy changes that reduce exposure to heat, or improve people’s susceptibility and adaptivity to heat.

“By looking at emergency department visits for different causes and for several age groups, we were able to characterise with accuracy the varying impact on health on different populations,” said study co-author, Professor Francesca Dominici. “An important goal of this study is to provide actionable information to clinicians and public health experts regarding how to prevent these emergency department visits, also considering that we can anticipate when these extreme heat events are likely to occur.”

Source: Boston University

Categories : Cardiovascular Disease Environmental EffectsTags :

Extreme Heat Threatens Cardiovascular Health

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Photo from Olivier Collett on Unsplash
Photo from Olivier Collett on Unsplash


With South Africa’s summer being expected to be both wetter and hotter this year, there is a greater risk of adverse cardiovascular incidents, especially for adults with pre-existing cardiovascular diseases. Experts writing in the Canadian Journal of Cardiology discuss how extreme heat affects cardiovascular health, why health professionals should care and what recommendations they can make to minimise consequences.

Extreme heat events are predicted to become longer, more common and more severe. Some 70 000 heat-related deaths occurred during the 2003 European heatwave. Risk factors for heat-related hospitalisation include age, chronic illnesses, social isolation, some medications, and lack of access to air conditioning. Among chronic illnesses, cardiovascular diseases are often identified as a risk factor for heat-related hospitalisation and death.

The Intergovernmental Panel on Climate Change (IPCC) recently reported that global temperatures are rising at a greater rate than previously projected, and that the number of extreme heat days will significantly increase across most land regions,” said senior author Daniel Gagnon, PhD, University of Montreal. “Although we don’t yet fully understand the reasons, people with cardiovascular disease are at greater risk of hospitalisations and death during extreme heat events.”

The researchers reviewed studies and noted a consistent association between extreme heat and increased risk of adverse cardiovascular outcomes. An examination of reviews and meta-analyses on the effect of extreme heat on adverse cardiovascular outcomes showed that heatwaves significantly increase mortality risk from ischaemic heart disease, stroke, and heart failure.

“Although the effects of extreme heat on adverse cardiovascular events have been explained in the context of heatstroke, many events occur without heatstroke, and the mechanisms of these events in the absence of heatstroke remain unclear,” observed Dr Gagnon. “It is likely that heat exposure increases myocardial oxygen needs.”

One possibility is that heat exposure puts excessive strain on the heart for individuals with heart disease and that heat exposure increases the risk of blood clots forming within cardiac blood vessels.

The authors propose that preventive strategies should aim to reduce the extent of hyperthermia and dehydration. In Canada, heat-health warnings systems act as a first line of defence by raising awareness of upcoming heat events and recommending strategies to minimise possible heat complications. For example, heat warnings are issued 18-24 hours before a heat event in Ontario and Québec, when ambient temperature will remain above 30°C for a minimum of two days. Public advisories include identifying the signs of heat stress, ensuring people drink adequate amounts of cold fluid or seeking an air-conditioned environment – though for many people, this is not an option.

Recent research supports electric fan use, skin wetting and immersing the feet in tap water as simple methods to stay cool during extreme heat events. “Air conditioning is the most effective strategy that can be recommended since it effectively removes the heat stimulus and minimises the risk of adverse cardiovascular outcomes,” commented Dr Gagnon. “However, less than one third of global households own air conditioning.”

More studies are needed to explain why extreme heat is linked to increased risk of adverse cardiovascular outcomes; the effect of cardiovascular medication on the human body’s physiological responses during heat exposure; the best cooling strategies in heat waves for individuals with CVD; and safe environmental limits for outdoor exercise in individuals with heart disease.

“Cardiovascular health professionals need to be aware of the negative consequences of extreme heat on cardiovascular health. A better awareness and understanding of the cardiovascular consequences of extreme heat, and of the measures to take to prevent and mitigate adverse events, will help us all assess the risk and optimize the care of patients exposed to an increasingly warm climate,” concluded Dr Gagnon.

Source: Elsevier

Categories : Environmental EffectsTags :

Tropical Areas Approaching Upper Limits for Survivable Heat

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Some people living in tropical regions are already living under conditions of heat stress that are approaching the upper limits of human survivability, a study has found.

In this study published in iScience, researchers noted that climate models used to predict heat conditions around the world are generally based on data from weather stations in relatively populated areas. Such data, they note, excludes conditions for people living in what they describe as informal settlements. To find out more about the conditions for people living in areas expected to be hit by the worst global warming effects, the researchers placed heat sensors in and around 100 houses in Makassar, Indonesia, a settlement in a tropical part of the country. The observed conditions are likely representative of many such settlements in the tropics, the researchers suggested.

Analysing the data, the researchers discovered that, during the rainy season, 80% of the sensors recorded temperatures in excess of established health thresholds. At such temperatures and humidity levels, adverse health impacts are said to be felt by people living there. In a few instances, they found that the sensors recorded temperatures that are believed to represent the upper limit of human survivability.

These findings are alarming for several reasons, they noted. For one, millions of people living in many parts of the world are already living under heat conditions that are harmful to their health. Another is the fact that many such people engage in physical labour for their livelihoods, and doing so in extreme heat can be fatal. Perhaps most alarming is the near certainty that conditions in such places are going to get worse as the planet continues to warm from fossil fuel burning and climate change. An analysis of the agreements reached at the COP26 summit found that the Earth was on course for a 2.4°C increase in temperature, well above the 1.5°C increase suggested by scientists to avoid the worst effects of climate change. For most such places, there are no relocation plans, and little chance that heat-mitigating technology such as air-conditioning will be installed. This suggests that a disaster of massive proportions is on the way.

Source: Phys.Org

Categories : Cardiovascular Disease Environmental EffectsTags :

High Altitude Protects against Stroke Risk

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While there are well-known common lifestyle and health factors that contribute to stroke risk, including smoking, high blood pressure, high cholesterol, and lack of physical activity, there is another overlooked factor that could also affect stroke risk – altitude.

Higher altitude means less oxygen availability, to which people living there have adapted. However, how this environment affects someone’s risk for stroke is still unclear. Anecdotal evidence suggests that short-term exposure to low oxygen can contribute to increased blood clotting and stroke risk, but the risk among people who permanently live at high altitude is not clear.

Researchers in Ecuador are in a unique position to explore these phenomena, as the presence of the Ecuadorian Andes means that people in the country live at a wide array of altitudes. Study lead author Esteban Ortiz-Prado, and Professor, Universidad de las Americas, explained:

“The main motivation of our work was to raise awareness of a problem that is very little explored. That is, more than 160 million people live above 2500 metres and there is very little information regarding epidemiological differences in terms of stroke at altitude. We wanted to contribute to new knowledge in this population that is often considered to be the same as the population living at sea level, and from a physiological point of view we are very different.”

The researchers drew on hospital records in Ecuador from between 2001 and 2017, and analysed rates of stroke hospitalisation and mortality among people who live at four different elevation ranges: low altitude (under 1500m), moderate altitude (1500­–2500m), high altitude (2500–3500m) and very high altitude (3500–5500m).

Analysis showed that people who lived at higher altitudes (above 2500m) tended to experience stroke at a later age compared with those at lower altitudes. Intriguingly, people who lived at higher altitudes had a lower stroke hospitalisation or mortality risk. This protective effect was greater between 2000 and 3500m, tapering off somewhat above 3500m. In South Africa, Johannesburg sits above 1700m altitude.

One explanation for this finding may be that people who live at high altitude have adapted to the low oxygen conditions, and more readily grow new blood vessels to help overcome stroke-related damage. They may also have a more developed vascular network in their brains that helps them to make the most of the oxygen they take in, but this could also protect them from the worst effects of stroke.

Source: Medical Xpress

Categories : Environmental EffectsTags :

Solar Exposure Guidelines Could be Revised

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Previously published solar exposure guidelines for optimal vitamin D synthesis that were based on a study of skin samples may have to be revised. 

A study published in PNAS has tested the optimum ultraviolet radiation (UVR) wavelengths for human skin production of vitamin D in sunlight.

Though UVR from sunlight can cause sunburn and skin cancer, it is the most important source of vitamin D.

Public health advice on sunshine exposure balances its risk and benefit, which is not a simple task because the health outcomes from UVR exposure vary considerably with wavelength within the sun’s UVR spectrum. For example, the sun’s UVR contains less than 5% short wavelength UVB radiation but this is responsible for over 80% of the sunburn response. Each health outcome from solar exposure has its own unique wavelength dependency.

The link between specific UVB wavelengths and vitamin D production was determined more than thirty years ago in ex vivo skin samples. However, the finding is less well established, with doubts on its accuracy which compromise risk/benefit calculations for optimal solar exposure.

Researchers led by the Professor Antony Young from King’s College London measured blood vitamin D levels in 75 healthy young volunteers, before, during, and after partial or full body exposure to five different artificial UVR sources with different amounts of UVB radiation, to gauge the trade-off between solar exposure benefits, which include vitamin D synthesis, versus the risks of sunburn and skin cancer.

The results were compared against predictions from the old ex vivo vitamin D study, finding that it was not an accurate predictor of benefit from UVR exposure.

The authors’ recommendation is a systematic correction of the ex vivo wavelength dependency for vitamin D. The new study means that many risk benefit calculations for solar UVR exposure must be reviewed with a revised version of the wavelength dependency for vitamin D.

“Our study shows that risk versus benefit calculations from solar exposure may need to be re-evaluated. The results from the study are timely because the global technical committee, Commission internationale de l’éclairage, that sets UVR standards will be able to discuss the findings of this paper to re-evaluate the wavelength dependency of vitamin D. Further research from our group will determine the risk/benefit calculations.”

Professor Antony Young, King’s College London

Source: King’s College London

Categories : Environmental EffectsTags :

WHO Tightens Air Quality Guidelines

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New WHO Global Air Quality Guidelines (AQGs) have lowered the acceptable limits of air pollution, providing evidence that even lower concentrations than previously understood have a negative health impact.

Increasing evidence showing how air pollution affects different aspects of health, WHO has adjusted almost all the AQGs levels downwards, warning that exceeding the new air quality guideline levels is associated with significant risks to health.

Air pollution is estimated to cause 7 million premature deaths and the loss of millions more healthy years of life. In children, this could include reduced lung growth and function, respiratory infections and aggravated asthma. In adults, deaths from ischaemic heart disease and stroke are the most common, as well as emerging evidence of diabetes and neurodegenerative conditions. This makes the disease burden from air pollution on par with others such as unhealthy diet and tobacco smoking.

Besides climate change, air pollution is one of the biggest environmental threats to human health. Improving air quality will also help mitigate climate change, thereby reducing the negative health impacts of both.
WHO’s new guidelines recommend air quality levels for 6 pollutants, where evidence has advanced the most on health effects from exposure. When action is taken on these so-called classical pollutants – particulate matter (PM), ozone (O₃), nitrogen dioxide (NO₂) sulfur dioxide (SO₂) and carbon monoxide (CO), it also has an impact on other damaging pollutants.

Particulate matter equal or smaller than 10 and 2.5 microns (µm) in diameter (PM₁₀ and PM₂.₅, respectively) is a particular health concern. Both PM₂.₅ and PM₁₀ can penetrate deep into the lungs but PM₂.₅ can even enter the bloodstream, primarily resulting in cardiovascular and respiratory impacts, and also affecting other organs, and were classified as carcinogenic in 2013.

“Air pollution is a threat to health in all countries, but it hits people in low- and middle-income countries the hardest,” said WHO Director-General, Dr Tedros Adhanom Ghebreyesus. “WHO’s new Air Quality Guidelines are an evidence-based and practical tool for improving the quality of the air on which all life depends. I urge all countries and all those fighting to protect our environment to put them to use to reduce suffering and save lives.”

In 2019, over 90% of the world’s population lived in areas where concentrations exceeded the 2005 WHO air quality guideline for long term exposure to PM₂.₅.

Almost 80% of PM₂.₅-related deaths could be avoided if current air pollution levels were reduced to those proposed in the updated guideline. At the same time, reaching interim targets would reduce the burden of disease, of which the greatest benefit would be observed in countries with high concentrations of fine particulates (PM₂.₅) and large populations.

Source: World Health Organization

Categories : Environmental Effects ExerciseTags :

‘Uncomfortable’ Urban Spaces Result in Slower, Uncertain Walking

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Stepping patterns become slower and more variable when a person is not comfortable with their environment, researchers have found.

The findings, published in PLoS One, shows that the perceived comfort of an environment, rather than it being natural or not, affects how people walk, with potential lessons for urban design.

Lead author Daria Burtan of Bristol’s School of Psychological Science said: “Measuring the changes of a person’s walking patterns through an environment allows us to understand their experienced comfort on a moment-to-moment basis.

“This is an important step toward being able to objectively quantify the impact of particular architectural designs on people’s wellbeing.”

Research has shown that spending time in green spaces such as parks helps improve attention spans, concentration and wellbeing, which can be shown by improvements in measured stepping patterns when walking in different environments.

Daria added: “As our cognitive faculties begin to decline in older age, the stepping patterns we make with our feet become slower and more variable, relative to when we are younger in the prime of our health. We found that the same thing happened when people walked toward images of urban and nature scenes they didn’t feel comfortable with – their stepping patterns became slower and more varied, relative to when they were looking at scenes they found comfortable and which they liked.

“Not only does this suggest that environments in which we feel comfortable and safe, place fewer processing demands on our brains; it demonstrates how measuring the real-time dynamics of our gait provides us with a powerful new tool for informing on the cognitive impacts of architecture and urban design.”

The researchers are now seeking to understand which psychological factors contribute to sensory discomfort.

Source: University of Bristol

Categories : Environmental EffectsTags :

Low-level Air Pollution Still Linked to Higher Mortality

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Long-term exposure to air pollution appears to still be linked to higher mortality despite the existence of air quality standards that restrict levels of pollution, suggests a study published online in The BMJ today.

Previous studies have found an association between long term exposure to outdoor air pollution such as those in the form of fine particles in the air (known as particulate matter or PM2.5) and nitrogen dioxide (NO2) and illness or mortality.

While air pollution concentrations have fallen substantially in Europe since the 1990s, it is unclear whether there still is a link between pollution and ill health or death at pollution levels under permitted levels.

Therefore, researchers set out to determine if there was an association between low levels of air pollution concentrations and natural and cause-specific deaths.

Low-level air pollution was defined as concentrations below current limits set by the European Union, US Environmental Protection Agency and the World Health Organization (WHO).

The researchers analysed data on eight groups of people within six European countries. Their study recruited participants in the 1990s or 2000s. Of the 325 367 participants who were followed up over an almost 20-year period, around 14.5% (47 131 people) died during the study period.

An increase of 5 µg/m3 (a concentration measure of particulate matter) in particulate matter (PM2.5) was associated with a 13% increase in natural deaths while the corresponding figure for a 10 µg/m3 increase in nitrogen dioxide was 8.6%. Associations with PM2.5 and NO2 were largely independent of each other.

Moreover, even at low to very low concentrations, associations with PM2.5, NO2, and black carbon remained significant. For people exposed to pollution levels below the US standard of 12 µg/m3, an increase of 5 µg/m3 in PM2.5 was associated with a 29.6% increase in natural deaths. People exposed to NO2at less than half the current EU standard of 40 µg/m3, a 10 µg/m3 increase in NO2 was associated with a 9.9% increase in natural deaths.

The study also has some limitations, the researchers said, such as the fact that it focused on exposure in 2010 which was towards the end of the follow-up period for most participants and, given falling air pollution, this measure might not exactly reflect the concentrations experienced during follow-up.

However, this was a large study from multiple European groups of people with detailed information provided. As such, the authors concluded: “Our study contributes to the evidence that outdoor air pollution is associated with mortality even at levels below the current European and North American standards and WHO guideline values.

“These findings are therefore an important contribution to the debate about revision of air quality limits, guidelines and standards, and future assessments by the Global Burden of Disease [study].”

Source: The BMJ