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Coronavirus: Air Pollution Might Raise Risk of Fatality
By Ajit Niranjan
Two main risk factors are currently known to raise the chance of dying from the novel coronavirus that has brought the world to a halt: being old and having a weak immune system.
Air pollution makes the second of those more likely.
"If you live in a polluted area, your lungs are compromised like somebody who smokes, so you're more susceptible to the coronavirus," said Kofi Amegah, an epidemiologist and air pollution expert at the University of Cape Coast in Ghana.
Dirty air, which claims more than 7 million lives a year, could make Covid-19 more deadly by contributing to chronic health conditions that leave patients weak in the face of infection.
The European Public Health Alliance said last week that air pollution is likely to cut survival chances from Covid-19.
Research on previous outbreaks has also suggested bad air makes viruses more deadly and spread further. A study of SARS-CoV-1 victims in 2003 found that patients were twice as likely to die in regions where air pollution was high rather than low. Even in regions that were only moderately polluted, the risk of dying was 84% higher.
If a similar dynamic exists for Covid-19, it could add pressure on the critical care units of hospitals in smoggy cities with rapidly rising cases, such as Madrid, London and New York. It could also spell trouble for countries in the global south where most people burn wood, dung, kerosene or coal indoors to cook and heat their homes.
In northern Italy and the Chinese city of Wuhan, home to high levels of pollution and some of the most severe outbreaks to date, preliminary data suggests that particulate matter may already have played a role in overwhelming health care systems.
PM2.5 — particulate matter smaller than 2.5 microns in diameter, less than the width of a human hair — can penetrate the lung barrier and enter the bloodstream, raising the risk of developing heart and lung disease.
The case fatality rate in China was nine times higher for people with cardiovascular disease and six times higher for patients with diabetes, hypertension and respiratory disease than it was for people without underlying health conditions, a joint study by the World Health Organization and China found in February.
In Italy, health officials reported in March that 99% of a sample of patients who died from Covid-19 had an underlying illness — with almost half the deceased having suffered from three or more — though the sample was not drawn randomly and may not represent the population. The most common ailments were high blood pressure, heart disease and diabetes.
The WHO says the pandemic is too recent to draw a link between air pollution and the deadliness of Covid-19, but this shouldn't stop countries from acting.
"Whether or not we have this correlation between Covid-19 and air pollution, we need to reduce air pollution no matter what," Maria Neira, director of public and environmental health at the World Health Organization, told DW.
"Stop smoking and reduce the levels of air pollution — that is a recommendation we can make even without having more evidence."
Together with ozone pollution, PM2.5 particles shave almost three years off our lives, a study in the journal Cardiovascular Research found last month. The global loss of life from outdoor air pollution is 10 times greater than that of all forms of violence put together.
Moreover, about nine in 10 premature deaths caused by air pollution — including toxic gases NO2 and SO2 — hit people in low and middle-income countries. Even within rich cities in Europe and North America, working class, black and ethnic minority communities tend to breathe the dirtiest air.
Across sub-Saharan Africa, women are particularly exposed to pollutants from indoor cooking.
"For these women, their lung systems are compromised," said Amegah from Ghana's University of Cape Coast, adding that if Covid-19 spreads they will be especially vulnerable.
"We pray and keep our fingers crossed we don't see the levels [we're seeing] in northern Italy and China."
As well as weakening the body, airborne pollutants could even act as a carrier of the new coronavirus and allow it to survive in the air attached to particulates, a team of Italian researchers suggested in March.
High concentrations of particulate matter in parts of northern Italy in February may have "boosted" the spread of the epidemic this way, according to a position paper published by the Italian Society of Environmental Medicine that has not yet been peer-reviewed.
Other scientists have cast doubt on this, pointing out that there are no reported cases of this coronavirus spreading in the air and that people are the main vector of transmission.
"It's good to reduce air pollution to promote health, even to help decrease preconditions that could aggravate coronavirus, such as asthma, but I cannot see [air pollution] as an important contribution to the discussion about containment of the virus," said Jos Lelieveld, director of atmospheric chemistry at the Max Planck Institute and lead author of the study on deaths from air pollution.
As coronavirus cases rise exponentially around the world, lockdowns to stop its spread have reduced pollution levels.
Satellite images of China and Italy show striking drops in NO2, a toxic gas that inflames the airways, as governments closed factories and kept cars off the streets. The drop in air pollution in China may even have saved more lives than were lost from Covid-19, a study that has not yet been peer-reviewed suggested on Friday, though this comparison does not factor in the lives that would have been lost had the coronavirus spread unchecked.
Not all of the fall in air pollution seen from space can be attributed to lockdowns, either. Air pollution is higher in colder months anyway because people heat more and drive cars more often, so it tends to fall around this time of year, said Christian Retscher of the European Space Agency.
"Certainly, we see an effect of the coronavirus on NO2 … We see an additional effect [but] we don't know the precise number."
While lockdowns have helped clean the air, it is also uncertain how long they will keep pollution levels down.
"Once the crisis is over, and we see this in China, there's a temptation to compensate for the weeks and months lost," said Zoltan Massay-Kosubek, a policy expert for clean air and sustainable transport at the European Public Health Alliance.
Nonetheless, this shows that air pollution can be reduced and lives saved, said the WHO's Neira. "Now we need to maintain that — not the fact that we'll be confined, but reducing the air pollution levels outside."
Reposted with permission from DW.
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EcoWatch Daily Newsletter
By Melissa Gaskill
Two decades ago scientists and volunteers along the Virginia coast started tossing seagrass seeds into barren seaside lagoons. Disease and an intense hurricane had wiped out the plants in the 1930s, and no nearby meadows could serve as a naturally dispersing source of seeds to bring them back.
Restored seagrass beds in Virginia now provide habitat for hundreds of thousands of scallops. Bob Orth, Virginia Institute of Marine Science / CC BY 2.0<p>The paper is part of a growing trend of evidence suggesting seagrass meadows can be easier to restore than other coastal habitats.</p><p>Successful seagrass-restoration methods include <a href="https://www.sciencedirect.com/science/article/abs/pii/S0304377099000078?via%3Dihub" target="_blank">transplanting shoots</a>, <a href="https://onlinelibrary.wiley.com/doi/10.1111/j.1061-2971.2004.00314.x" target="_blank" rel="noopener noreferrer">mechanized planting</a> and, more recently, <a href="https://www.nature.com/articles/s41467-020-17438-4" target="_blank" rel="noopener noreferrer">biodegradable mats</a>. Removing threats, proximity to donor seagrass beds, planting techniques, project size and site selection all play roles in a restoration effort's success.</p><p>Human assistance isn't always necessary, though. In areas where some beds remain, seagrass can even recover on its own when stressors are reduced or removed. For example, seagrass began to recover when Tampa Bay improved its water quality by reducing nitrogen loads from runoff by roughly 90%.</p><p>But more and more, seagrass meadows struggle to hang on.</p><p>The marine flowering plants have declined globally since the 1930s and currently disappear at a rate equivalent to a football field every 30 minutes, according to the <a href="https://www.unep.org/resources/report/out-blue-value-seagrasses-environment-and-people" target="_blank" rel="noopener noreferrer">United Nations Environment Programme</a>. And research published in 2018 found the rate of decline is <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GB005941" target="_blank" rel="noopener noreferrer">accelerating</a> in many regions.</p><p>The causes of decline vary and overlap, depending on the region. They include thermal stress from climate change; human activities such as dredging, anchoring and coastal infrastructure; and intentional removal in tourist areas. In addition, increased runoff from land carries sediment that clouds the water, blocking sunlight the plants need for photosynthesis. Runoff can also carry contaminants and nutrients from fertilizer that disrupt habitats and cause algal blooms.</p><p>All that damage comes with a cost.</p>
The Value of Seagrass<p>As with ecosystems like rainforests and <a href="https://therevelator.org/mangroves-climate-change/" target="_blank">mangroves</a>, loss of seagrass increases carbon dioxide emissions. And that spells trouble not just for certain habitats but for the whole planet.</p><p>Although seagrass covers at most 0.2% of the seabed, it <a href="https://www.unenvironment.org/news-and-stories/story/seagrass-secret-weapon-fight-against-global-heating" target="_blank">accounts for 10%</a> of the ocean's capacity to store carbon and soils, and these meadows store carbon dioxide an estimated 30 times faster than most terrestrial forests. Slow decomposition rates in seagrass sediments contribute to their <a href="https://www.researchgate.net/publication/238506081_Assessing_the_capacity_of_seagrass_meadows_for_carbon_burial_Current_limitations_and_future_strategies" target="_blank" rel="noopener noreferrer">high carbon burial rates</a>. In Australia, according to <a href="https://onlinelibrary.wiley.com/doi/10.1111/gcb.15204" target="_blank" rel="noopener noreferrer">research</a> by scientists at Edith Cowan University, loss of seagrass meadows since the 1950s has increased carbon dioxide emissions by an amount equivalent to 5 million cars a year. The United Nations Environment Programme reports that a 29% decline in seagrass in Chesapeake Bay between 1991 and 2006 resulted in an estimated loss of up to 1.8 million tons of carbon.</p>
Eelgrass in the river delta at Prince William Sound, Alaska. Alaska ShoreZone Program NOAA / NMFS / AKFSC; Courtesy of Mandy Lindeberg / NOAA / NMFS / AKFSC<p>Seagrasses also protect costal habitats. A healthy meadow slows wave energy, reduces erosion and lowers the risk of flooding. In Morro Bay, California, a 90% decline in the seagrass species known as eelgrass caused extensive erosion, according to a <a href="https://www.sciencedirect.com/science/article/abs/pii/S0272771420303528?via%3Dihub" target="_blank" rel="noopener noreferrer">paper</a> from researchers at California Polytechnic State University.</p><p>"Right away, we noticed big patterns in sediment loss or erosion," said lead author Ryan Walter. "Many studies have shown this on individual eelgrass beds, but very few studies looked at it on a systemwide scale."</p><p>In the tropics, seagrass's natural protection can reduce the need for expensive and often-environmentally unfriendly <a href="https://www.nioz.nl/en/news/zeegras-spaart-stranden-en-geld" target="_blank" rel="noopener noreferrer">beach nourishments</a> regularly conducted in tourism areas.</p><p>Seagrass ecosystems improve water quality and clarity, filtering particles out of the water column and preventing resuspension of sediment. This role could be even more important in the future. By producing oxygen through photosynthesis, meadows could help offset decreased oxygen levels caused by warmer water temperatures (oxygen is less soluble in warm than in cold water).</p><p>The meadows also provide vital habitat for a wide variety of marine life, including fish, sea turtles, birds, marine mammals such as manatees, invertebrates and algae. They provide nursery habitat for <a href="https://wedocs.unep.org/bitstream/handle/20.500.11822/32636/seagrass.pdf?sequence=1&isAllowed=y" target="_blank" rel="noopener noreferrer">roughly 20%</a> of the world's largest fisheries — an <a href="https://www.floridamuseum.ufl.edu/science/seagrass-meadows-harbor-wildlife-for-centuries/" target="_blank" rel="noopener noreferrer">estimated 70%</a> of fish habitats in Florida alone.</p><p>Conversely, their disappearance can contribute to die-offs of marine life. The loss of more than 20 square miles of seagrass in Florida's Biscayne Bay may have helped set the stage for a widespread <a href="https://www.wlrn.org/2020-08-14/the-seagrass-died-that-may-have-triggered-a-widespread-fish-kill-in-biscayne-bay" target="_blank">fish kill</a> in summer 2020. Lack of grasses to produce oxygen left the basin more vulnerable when temperatures rose and oxygen levels dropped as a result, says Florida International University professor Piero Gardinali.</p>
Damaged Systems, a Changing Climate<p>Governments and conservationists around the world have already put a lot of effort into coastal restoration efforts. And that's helped some seagrass populations.</p><p>Where stressors remain, though, restoration grows more complicated. <a href="https://www.rug.nl/research/portal/en/publications/the-future-of-seagrass-ecosystem-services-in-a-changing-world(3a8c56db-7bed-4c9e-ac7f-c72453e2a102).html" target="_blank">Research</a> published this September found that only 37% of seagrass restorations have survived. Newly restored meadows remain vulnerable to the original stressors that depleted them, as well as to storms — and <a href="https://www.ecowatch.com/tag/climate-crisis">climate change</a>.</p>
Seagrass in Dry Tortugas National Park, Florida. Alicia Wellman / Florida Fish and Wildlife / CC BY-NC-ND 2.0<p>In Chesapeake Bay a cold-water species of seagrass is currently hitting its heat limit, especially in summer, according to Alexander Challen Hyman of University of Florida's School of Natural Resources and Environment. As waters continue to warm due to climate change, the species likely will disappear there.</p><p>Climate-driven sea-level rise complicates the problem as well. Seagrasses thrive at specific depths — too shallow and they dry out or are eaten, too deep and there isn't enough light for photosynthesis.</p>
But There’s Good News, Too<p>Luckily, left to its own devices, a seagrass meadow can flourish for hundreds of years, according to a <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2019.1861" target="_blank" rel="noopener noreferrer">paper</a> published last year by Hyman and other researchers from the University of Florida. The researchers arrived at their conclusion by looking at shells of living mollusks and fossil shells to estimate the ages of meadows in Florida's Big Bend region on the Gulf Coast.</p><p>That area has extensive, relatively pristine seagrass meadows. "Our motivation was to understand the past history of these systems, and shells store a lot of history," said co-author Michal Kowalewski.</p><p>A high degree of similarity between living and dead shells indicates a stable area, while a mismatch suggests an area shifted from seagrass to barren sand. The researchers found that long-term accumulations of shells resembled living ones, suggesting that the seagrass habitats have been stable over time.</p><p>That stability allows biodiversity to thrive, creating conditions where specialist species can survive and flourish, according to Hyman.</p><p>Discovering the long-term stability of seagrass meadows has implications for choosing restoration sites, Kowalewski notes.</p><p>"There must be reasons they thrive in one place, while a mile away they don't and fossil data says they probably never did," he said. "If we remove a seagrass patch, we cannot hope to plant it somewhere else. It's not just the seagrass that is special. The location at which it's found is special, too."</p><p>A better approach is conserving these habitats in the first place, but we're not doing enough of that right now. The UN reports that marine protected areas safeguard just 26% of recorded seagrass meadows, compared with 40% of coral reefs and 43% of mangroves.</p>
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