When storms trigger asthma

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Nature and Environment Australia https://p.dw.com/p/5Nysb

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TRANSCRIPT

Dave McGann: I remember sitting on the couch, um, and my chest just started getting a little bit tight…”

It’s Monday evening and Dave McGann is in his apartment in Melbourne, Australia.

Dave: …within sort of, maybe half an hour I could breathe in about half capacity, 50% capacity, of what I normally could. And I thought, “geez, that is really strange.”

It’s a sweltering spring day in Melbourne, with temperatures peaking at 95 degrees Fahrenheit.

Dave: I remember it being really sunny…

Dave has just ridden his bike home from the downtown law office where he works, like he does every day.

Dave: It was getting stormy on the way home, but like I ride home rain, hail or shine. So, you know, getting wet doesn’t bother me.

I just remember that kind of thick, heavy, uh, humidity kind of feeling. …Thick, humid, dark, storm… I do remember it just getting super dark early.

He’s home when the storm hits at about 6pm.

Dave: … Melbourne weather can change so quickly and so drastically that, you know, it wasn’t out of the ordinary for it to do that later on.

What IS out of the ordinary, though, is the tightening in Dave’s chest. He doesn’t know what’s happening to him.

Dave: It was very unusual to be out of breath like that.

As the night goes on, his breathing gets worse. Eventually, Dave realizes he needs help.

Dave: … I remember laying in bed for 15 minutes and, um, I just thought I could barely breathe. I don’t know what’s going on, but I’m starting to freak out. It felt like an elephant sitting on my chest. Um, I’m sure a baby elephant, but I guess like my feeling is that I felt trapped. I couldn’t do anything. I didn’t have strength and I just felt trapped.

With the panic rising, Dave realizes he has to do something. So he googles where the nearest 24-hour pharmacy is and gets dressed.

Dave: And that was the moment where I thought, Holy…, you know, what the hell is going on? Because here I am in the middle of the night. You know, usually I’m sound asleep… I was escalating, you know, like I was like starting to get worried.

When he pulls up at the pharmacy he realizes he’s not the only person struggling to breathe.

Dave: On approach, I could see a line of people out the door and I was like, “oh, this is just bizarre. Like, something’s going on here,” … people were crying… There’s like a queue snaking and like, the people that worked there were as confused as we were. It felt like it was out of a movie and like, I just remember the staff just like flinging out asthma puffers for free. They’re just like, “Get this into you,” and “we don’t know what’s going on.”

Dave is experiencing what’s known as “thunderstorm asthma.”

So are thousands of other Melburnians. Most of them have no history of asthma. But they’re all having asthma attacks – triggered by the storm. The date is November 21, 20216.

Across the city that night, an estimated 10,000 people are rushed to hospital with breathing problems. The health system is stretched to its limits. Ambulance call lines are flooded, emergency rooms full. Ten people lose their lives.

Kira Hughes: What some Melbourne hospitals had to do on the day – they had to call an emergency code brown, which is usually reserved for natural disasters, because they just didn’t have enough beds for the patients that were coming in over the hours following the storm hitting.

That’s Kira Hughes. She’s an honorary fellow at Melbourne’s Deakin University who studies thunderstorm asthma.

Kira: The symptoms can hit within 15 minutes of exposure to the thunderstorm. So even just going outside for a couple of minutes impacted people…

60% of the people who ended up in hospital that night had had never been diagnosed with asthma.

Kira: They didn’t know what they were experiencing. They didn’t have medication or a way to treat it… And ambulances then took forever because they were helping out so many other people. It was a lot of things that culminated in this disaster, some that could have been prevented, some that couldn’t. But all we can do from now is just learn and do more research into why these things happen so we can prevent future disasters.

But what almost all of them did have was hay fever. They were sensitized to pollen from rye grass fields north of Melbourne that was sept up by the storm.

It might sound surprising, but asthma isn’t the biggest risk factor for thunderstorm asthma. People with a pollen allergy are actually most at risk. But it can really affect anyone. In Dave’s case, he says he only had mild allergies and occasional asthma symptoms as a kid. So he was caught off guard when he suddenly started struggling to breathe.

What happened that night is considered to be the worst thunderstorm asthma event recorded globally. But this isn’t just some kind of freak phenomenon unique to Melbourne.

Thunderstorm asthma has been reported all over the world from China, Iran, Italy, the UK, and the US.

Kira: So there is potential for them to happen in all these different places.

And that potential is likely growing.

Now, thunderstorm asthma events are rare. But scientists say climate change could make them more common and more difficult to predict in the future.

Kira: We’re seeing more bushfires, we’re seeing more droughts, we’re seeing more tornadoes, and we’re also seeing more thunderstorms… And that is potentially going to get worse and worse.

At the same time, rising temperatures are making pollen seasons longer and more intense.

Kira: We’re getting a ton more pollen than we used to.

And rising levels of CO2 in the atmosphere are causing some plants to produce more pollen. It’s a combination that could mean more thunderstorm asthma in the future. That’s bad news for the millions of people who suffer with pollen allergies.

Kira: It does feel like it’s out of our control. We can’t stop the weather. We can’t stop storms. We can’t stop plants from producing pollen. All we can do is just try and help people be more aware of the preventative measures that they can put in place.

So how to prepare for a future with more pollen – and potentially more asthma-inducing storms?

I’m Neil King. And if you’re someone who has seasonal allergies, you’re going to want to stick around for this episode of Living Planet.

Kira: I’ve pretty much had hay fever and asthma my entire life, but it has gotten worse as the years have gone on…

Kira Hughes isn’t just studying the risks of pollen and thunderstorm asthma. She lives with them.

Kira: I mean, it is scary. Like I’m basically living in the thunderstorm asthma hot spot as one of the prime candidates for someone at risk of it.

She takes medication daily to manage her asthma. The last time she had an allergy test at the doctor…

Kira: …my reaction to grass and birch pollen was so bad that my arm swelled up and I couldn’t move it for two days.

Kira is among the more than 400 million people worldwide who have hay fever.

Kira: I’ll also tell people that I know how bad the pollen is going to be each day, depending on if my eyes are runny as soon as I wake up.

If you have seasonal allergies too, you’ll be familiar with the sneezing, the runny nose, the itching eyes, scratchy throat etc. etc. that often come with pollen season … …when trees, grasses and weeds release huge amounts of tiny pollen grains to be carried by the wind.

Pollen can also trigger allergic asthma. That’s the most common kind of asthma.

In the US, one in four adults have hay fever or seasonal allergies. That’s also the case in Australia and the UK. It’s something that tends to disproportionately affect people in developed countries and urban areas.

And it can be debilitating.

Studies show that people with allergies have worse sleep than healthy individuals and experience higher rates of depressive symptoms and exhaustion on days with high pollen counts.

There are economic consequences too. Lost productivity and medical treatment for seasonal allergies cost the EU and the US billions each year.

In one study, people with hay fever reported a 20 percent drop in productivity at work. There’s also evidence that children perform worse in school tests on high pollen days.

Pollen’s influence on allergy sufferers may not be as headline grabbing as floods or wildfires. But it’s part of a creeping health issue that’s set to get worse – partly thanks to how human activities are affecting the planet.

Allison: this is kind of one of the unintended effects of climate change and temperature change is that it might alter seasons and how you’re exposed to pollen.

Professor Allison Steiner is an atmospheric scientist at the University of Michigan.

Allison: I think as temperatures increase, we know that that’s shifting the pollen seasons, both in terms of timing and the length and that we will continue to see how much that’s going to happen really depends upon the long term projections of temperature.

Studies from around the world have shown that warmer temperatures are causing some plants to flower earlier in the year – and for longer.

One US paper from 2020 looked at long-term pollen records from 60 cities across North America. It found the overall pollen season was around 20 days longer than it was in 1990. And that pollen concentrations in the air had increased by over 20 percent – partly due to human-driven climate change. The biggest jumps were in Texas and the Midwest.

And… there’s another thing likely shaping the pollen prognosis: Carbon dioxide.

Allison: As CO2 concentrations increase in the atmosphere. And those are largely increasing because we’re burning more fossil fuels and we’re putting more CO2 into the atmosphere that can actually, in some cases, allow plants to photosynthesize faster. And so one big question is how that might influence pollen production.

Planet-heating CO2 serves as a kind of fertilizer, supercharging plant growth. It’s been shown to boost pollen production and even make the pollen itself more potent – triggering stronger allergic reactions in people.

In one experiment, ragweed plants exposed to CO2 concentrations from the year 2000 increased pollen production by 130% compared to specimens exposed to CO2 levels from 1890.

Another study looking at oaks in South Korea found that trees kept under elevated CO2 levels produced significantly more pollen, as well as more allergenic protein. Research has also found allergenic grasses exposed to high CO2 concentrations increased pollen production by 50%.

So what could that mean for the future – if the world keeps emitting large amounts of CO2? A study Allison co-authored in 2022 predicted the US could face a 200% increase in pollen by the end of the century.

Allison: Looking at these temperature changes, precipitation changes, potential for CO2 changes. And actually the northeastern US was where we saw a lot of increase as well as also the southeastern US, we saw a large increase in oak. And this Cupressaceae, which is the conifer species. So the eastern part of the US was much more heavily influenced.

But Allison points out there’s a lot of uncertainty with pollen predictions. There can be difficult-to-explain fluctuations from year to year, as well as other shifts caused by wind, rain and drought. She also says a drop in greenhouse gas emissions in the future will probably cause pollen levels to stabilize.

Allison: When we see those large increases in pollen, those were kind of our worst case scenarios with our warmest temperatures. I don’t think we’ll reach those extreme temperatures by 2100. I think we will see changes in emissions that will slow the global rise of temperatures. But we’ll still have warmer temperatures that will influence the pollen season.

So to recap: Overall, a hotter world with higher CO2 concentrations in the atmosphere means many trees and plants producing more pollen – over a longer period. And in some cases, the pollen they’re producing is more potent.

At the same time, the number of people with hay fever appears to be growing. So there’ll be more people with pollen allergies – suffering for longer, and potentially with worse reactions.

Now, add storms into the mix.

Climate change is making them more common.

Storms can keep pollen in the air for longer, or carry it over greater distances. Or cause asthma outbreaks like the one in Melbourne we heard about at the start of the episode.

Allison: There’s definitely a growing concern about thunderstorm asthma cases. I think it’s just been hard to document.

Scientists like Allison and Kira are working to get a better understanding of how these events unfold, so they can predict when they might happen.

What they do know is that there needs to be a specific kind of powerful thunderstorm, with warm moist air rising into the atmosphere, sucking up pollen grains with it. The moisture is what causes the pollen to expand and then explode into hundreds of much tinier particles.

Kira: …like a water balloon bursting, or even sometimes if lightning strikes it like, or electrical discharge can break it up.

Intact pollen grains are too big to get into the lungs. They typically get trapped in the nose or throat, where they can cause hay fever. But these tiny, broken-up particles? They can enter the lungs and trigger asthma. The storm just needs to have strong downdrafts to bring the pollen back down to the ground, where people can breathe them in.

Allison: So we’ve actually been looking at this in the central US because that’s sort of the spawning ground for a lot of the big, what atmospheric scientists call mesoscale convective systems…

These strong storm systems happen frequently in the US Midwest during springtime.

Allison: The central Great Plains is one where we see a lot of those systems, and we also see a lot of deep convection in the southeast and northeastern US. So yeah, it is definitely a concern.

Although nowhere near the scale of the event in Melbourne, data from some US cities such as Minneapolis and Atlanta has linked these thunderstorms to spikes in people reporting asthma symptoms. One recent study out of Wichita, Kansas, found asthma-related visits to hospital emergency rooms rose five-fold on days when there was a thunderstorm.

Wichita, by the way, has won the unlucky title of the worst US city to live with a pollen allergy in three of the past five years. It’s a ranking compiled by the Asthma and Allergy Foundation of America each year. But I digress…

Kira says there are still a lot of unknowns when it comes to what makes a perfect pollen storm. For example, they don’t know how big a role air pressure or temperature play in these events…

Kira: We don’t know how much wind there has to be. We don’t know how much rain there has to be…

Other elements like pollution, or fungal spores in the air, could also be relevant. But more research is needed.

Kira’s in the right place for that, because Melbourne is something of a hotspot for thunderstorm asthma. Around a quarter of the world’s major thunderstorm asthma events have happened here. The phenomenon was first described in the UK city of Birmingham in 1983. Since then, at least 26 events have been officially recorded globally. Kira says not included in that figure are the many suspected cases that have also been reported.

Kira: These events are so rare and we’re only really studying them in retrospect, like looking back at all the information that we have and all the data that we’ve collected. It’s basically all we have, unfortunately. We don’t want more of these events to happen, but we won’t be able to study them otherwise…

So if you struggle with seasonal allergies… what can you do?

Besides medication, the main way to prevent symptoms is to stay away from pollen.

But to do that, you need to know when there’s a lot of pollen outside. That’s why reliable pollen forecasting is so important.

Allison: It’s always been surprising to me, given the number of people who are affected by seasonal allergies, that we don’t have better data on this, but it’s still very sparse.

Allison says pollen monitoring stations aren’t widespread across the US. And the way pollen is counted…

Allison: … is a very manual, time intensive process.

Often a large, vacuum-like device on top of a building is used to trap pollen in the air. A trained technician then needs to collect the pollen samples and manually count the tiny grains under a microscope.

Allison: So you can identify what kind of pollen you have based on the size and shape.

This work can take several hours. And that information is then used to make a forecast for the next days. But there are gaps. For example, Allison says many monitoring stations don’t count pollen on weekends or outside of the main pollen season.

She’s currently working on a model with the National Oceanic and Atmospheric Administration – or NOAA – to create more accurate, real-time pollen forecasts. They’re using satellite data to estimate where trees are growing and looking at how things like temperature, rain, wind and humidity influence the amount of pollen in the air and how it moves around.

Allison: And then we’re putting that into the model to try to see if we can develop better pollen forecasts that are open and free. I mean we have the model working and running and we have some experimental results and we’re still working on validating it versus the ground based observations. Again, which are pretty hard to come by, and there aren’t that many sampling stations.

Automated pollen stations are starting to be used in the US – ones that use machine learning algorithms and image recognition software, rather than a person, to deliver faster results. Allison says these new systems could really make a difference.

Allison: … with the advent of new instrumentation and also with more, um, speedy computer algorithms that can do this identification. I think over the next 5 to 10 years, we’re going to see big changes in the amount of data that’s available.

…the more data we have the better the forecasts will become over time.

In Melbourne, the norm was also counting pollen manually to make a forecast, usually for the next day.

That was part of the problem in 2016. On the night of the storm, grass pollen concentrations in the city were extremely high, but authorities couldn’t see that at the time.

A lot has changed in the 10 years since. There are more pollen monitoring stations, they’re using automated technology, and there’s a forecasting system specifically for thunderstorm asthma risk.

Kira: There are constant warnings that are put out every spring, every time there’s a hint of a thunderstorm coming on a high pollen day.

There are alerts that hospitals will send out now if they have, um, like an exponential increase in asthma presentations over a short amount of time that gets sent out to all the other hospitals and the ambulance network to basically say that like we could have like a thunderstorm asthma event coming…So I think we’re as ready as we can be at the moment.

For her part, Kira wants to make sure an event like that doesn’t happen again. She’s currently developing a tiny pollen sensor – about the size of a coin – that can detect how much pollen is in the air from any location – not just at an official monitoring site.

Kira: It’s kind of similar to a smoke detector crossed with a scale is the best way I like to describe it. It’s basically a tiny electrode that’s sensitive to mass. So if anything like, you know, presses on it…

Like grass pollen, for instance

Kira: … the heavier it is, the stronger signal it sends out. And you can basically detect that with a computer.

It delivers accurate results in less than an hour. So close to real-time. But Kira says they’re still testing to make sure the device holds up well outside the lab. She says ideally the tiny sensor could be worn like a pendant or watch.

Kira: The dream would be to have something that’s wearable that people could take with them, and then they could get an alert on their phone if there is pollen near them… that can detect pollen in real time and tell you exactly what the pollen is, where you are within a given time.

…That sensor is still a couple of years off getting on the market basically because, um, we’re still in such early stages.

With climate change set to increase the pollen risk, Kira hopes the sensor will help people with allergies monitor the air around them. Especially when spring thunderstorms are forecast.

But in the meantime, she says there are other things people can do to prepare.

Kira: I mostly just tell people just to be vigilant…

Kira recommends people keep up to date with pollen forecasts and stay indoors with the windows closed if the pollen count is high. Or if you have to go out, protect yourself with a mask. And when you get home after spending time outdoors, change your clothes, have a shower and rinse the pollen from your hair.

Kira: Even sometimes during spring, I’ll have friends message me asking if it’s going to be a high pollen day or if there’s a thunderstorm asthma risk. I’ve just become that person in my friend group.

Now every time that a storm happens, I always need to be prepared. I feel like is this the day? Is this the day that we have another one?

As for Dave, who we heard from right at the start of the episode… he makes sure he has an asthma inhaler in his cupboard, just in case. Struggling for air is not an experience he cares to repeat.

Dave: I’m someone that generally kind of, you know, moves on and looks forward…I’ve never had an anxious thought about a thunderstorm, or “I hope it doesn’t happen” or anything.

But still, after what he went through, he has decided to make one change. He keeps an asthma inhaler on hand, just in case.

Dave: It was an awful feeling. So yeah, not worth it. And it seems like such a simple little solution.

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