Climate change set to increase air pollution deaths by hundreds of thousands by 2100

Guang Zeng, National Institute of Water and Atmospheric Research and Jason West, University of North Carolina – Chapel Hill

Climate change is set to increase the amount of ground-level ozone and fine particle pollution we breathe, which leads to lung disease, heart conditions, and stroke. Less rain and more heat means this pollution will stay in the air for longer, creating more health problems.

Our research, published in Nature Climate Change, found that if climate change continues unabated, it will cause about 60,000 extra deaths globally each year by 2030, and 260,000 deaths annually by 2100, as a result of the impact of these changes on pollution.

This is the most comprehensive study to date on the effects of climate change on global air quality and health. Researchers from the United States, the United Kingdom, France, Japan and New Zealand between them used nine different global chemistry-climate models.

Most models showed an increase in likely deaths – the clearest signal yet of the harm climate change will do to air quality and human health, adding to the millions of people who die from air pollution every year.

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Read more: Can we blame climate change for thunderstorm asthma?

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Stagnant air

Climate change fundamentally alters the air currents that move pollution across continents and between the lower and higher layers of the atmosphere. This means that where air becomes more stagnant in a future climate, pollution stays near the ground in higher concentrations.

Ground-level ozone is created when chemical pollution (such as emissions from cars or manufacturing plants) reacts in the presence of sunlight. As climate change makes an area warmer and drier, it will produce more ozone.

Fine particles are a mixture of small solids and liquid droplets suspended in air. Examples include black carbon, organic carbon, soot, smoke and dust. These fine particles, which are known to cause lung diseases, are emitted from industry, transport and residential sources. Less rain means that fine particles stay in the air for longer.

While fine particles and ozone both occur naturally, human activity has increased them substantially.

The Intergovernmental Panel on Climate Change has used four different future climate scenarios, representing optimistic to pessimistic levels of emissions reduction.

In a previous study, we modelled air pollution-related deaths between 2000 and 2100 based on the most pessimistic of these scenarios. This assumes large population growth, modest improvements in emissions-reducing technology, and ineffectual climate change policy.

That earlier study found that while global deaths related to ozone increase in the future, those related to fine particles decrease markedly under this scenario.

Emissions will likely lead to deaths

In our new study, we isolated the effects of climate change on global air pollution, by using emissions from the year 2000 together with simulations of climate for 2030 and 2100.

The projected air pollutant changes due to climate change were then used in a health risk assessment model. That model takes into account population growth, how susceptible a population is to health issues and how that might change over time, and the mortality risk from respiratory and heart diseases and lung cancer.

In simulations with our nine chemistry-climate models, we found that climate change caused 14% of the projected increase in ozone-related mortality by 2100, and offset the projected decrease in deaths related to fine particles by 16%.

Our models show that premature deaths increase in all regions due to climate change, except in Africa, and are greatest in India and East Asia.

Using multiple models makes the results more robust than using a single model. There is some spread of results amongst the nine models used here, with a few models estimating that climate change may decrease air pollution-related deaths. This highlights that results from any study using a single model should be interpreted with caution.

Australia and New Zealand are both relatively unpolluted compared with countries in the Northern Hemisphere. Therefore, both ozone and fine particle pollution currently cause relatively few deaths in both countries. However, we found that under climate change the risk will likely increase.

This paper highlights that climate change will increase human mortality through changes in air pollution. These health impacts add to others that climate change will also cause, including from heat stress, severe storms and the spread of infectious diseases. By impacting air quality, climate change will likely offset the benefits of other measures to improve air quality.

Guang Zeng, Atmospheric Scientist, National Institute of Water and Atmospheric Research and Jason West, Associate Professor, Department of Environmental Sciences and Engineering , University of North Carolina – Chapel Hill

This article was originally published on The Conversation. Read the original article.

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Snakebites are rarer than you think, but if you collapse, CPR can save your life

Bites from brown snakes like this one were the most common, followed by
tiger snakes, then red-bellied black snakes.
Matt Clancy/SunOfErat/Wikimedia Commons, CC BY-SA

Geoff Isbister, University of Newcastle

Despite the common belief that Australia has some of the most venomous snakes in the world, our new research shows being bitten by a snake is uncommon in Australia and dying from a snakebite is very rare.

And of the few unlucky people to collapse after venom enters their bloodstream, a bystander performing cardiopulmonary resuscitation (CPR) is the most likely thing to save them.

These are just some of the findings from 10 years of data from the Australian Snakebite Project published today in the Medical Journal of Australia.

Although many people go to hospital with a suspected snakebite, many do not turn out to have envenomation (when venom enters the bloodstream) after all.

In more than 90% of cases people are bitten by a non-venomous snake, venom is not injected when the snake bites (known as a “dry bite”) or are not even bitten by a snake (known as a “stick” bite).

Our analysis of about 1,548 cases of suspected snakebites from all around Australia, showed there were on average just under 100 snake envenomations a year, and about two deaths a year.

The most common snakebites were from brown snakes, then tiger snakes and red-bellied black snakes. Brown snakes were responsible for 40% of envenomations. Collapsing, then having a heart attack out of hospital was the most common cause of death (ten out of 23), and most deaths were from brown snakes.

What happens after a snakebite and how can CPR help?

Venom from a snakebite travels via the lymphatic system to the bloodstream. There, it circulates to nerves and muscles where it can cause paralysis and muscle damage. In the blood itself, the venom destroys clotting factors, which makes the blood unable to clot, increasing the risk of bleeding.

In the most severe cases, most commonly in brown snake bites, someone can collapse because they have low blood pressure (we don’t know for certain what causes the low blood pressure). In this situation, insufficient blood is pumped around the body for the brain and other vital organs.

Clearly the accurate diagnosis of snake envenomation and the timely administration of antivenom are essential to treating snakebites in hospital.

But when people collapse, CPR will keep the blood circulating to the vital organs – and is life-saving – however inexpertly a bystander performs it.

If a snakebite victim collapses, CPR is vital to keep the blood circulating to the vital organs.
from www.shutterstock.com

In other words, we found basic first aid before people reached hospital, of which bystander CPR is one, may be more important than any changes in how people are treated in hospital to improve people’s chance of survival. People who survived after collapsing received CPR on average within one minute of being bitten compared with 15 minutes for those who died.

Our study also showed that in most cases, people used other first-aid measures (pressure bandages and immobilising both the limb and the patient). These aim to prevent the venom travelling from the bite site, via the lymphatic system, to the bloodstream.

Antivenom saves lives for those who need it

Our study confirmed the role of antivenom in treating snakebites and the need for it to be administered before irreversible damage is done to the nervous system and paralysis occurs.

However, we found one in four patients given antivenom had an allergic reaction to it and about one in 20 have severe anaphylaxis requiring urgent treatment.

So it is essential only patients with snake envenomation, and not just a suspected snakebite, are treated with antivenom. We found 49 patients (around 6%) were given antivenom unnecessarily, out of the total 755 patients who received it.

What needs to change?

We know the earlier someone receives antivenom the better. Yet our study found that the time from being bitten until receiving antivenom had not improved over the study period.

So we need to find ways to make sure patients get antivenom as early as possible. This requires laboratory tests that can identify patients with snake envenomation in the first couple of hours after the bite.

It is also essential anyone bitten by a snake or suspected to be bitten by a snake seeks immediate medical attention and goes to hospital by ambulance.

But the best thing is to avoid being bitten in the first place:

• avoid snakes, difficult if you’re a snake handler (up to 11% of cases in our study), and take care if trying to catch or kill a snake (which led to a bite in 14% of cases)
• wear long pants and sturdy shoes when walking in the bush or rural areas (47% of snakebites were when people didn’t know one was nearby) or when gardening (8% of cases)
• be alert inside too, with 31% of snakebites near houses and 14% in buildings.

Our study confirms Australian snakes don’t really deserve their deadly reputation, unless you’re a mouse. But if you are bitten, or think you have been, hospital is still the best place for you.

Geoff Isbister, Director, Clinical Toxicology Research Group, University of Newcastle

This article was originally published on The Conversation. Read the original article.

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