When spring arrives, so do warnings about thunderstorm asthma. But a decade ago, most of us hadn’t heard of it.

So where did thunderstorm asthma come from? Is it a new phenomenon?

In 2016, the world’s most catastrophic thunderstorm asthma event took Melbourne by surprise. An increase in warnings and monitoring is partly a response to this.

But there are also signs climate change may be exacerbating the likelihood of thunderstorm asthma, with more extreme weather, extended pollen seasons and a rise in Australians reporting hay fever.

A landmark catastrophe

The first time many Australians heard of thunderstorm asthma was in November 2016, when a major event rocked Melbourne.

During a late night storm, an estimated 10,000 people were rushed to hospitals with severe asthma attacks. With thousands of calls on emergency lines, ambulances and emergency departments were unprepared to handle the rapid increase in people needing urgent medical care. Tragically, ten of those people died.

This was the most catastrophic thunderstorm asthma event in recorded history and the first time deaths have ever occurred anywhere in the world.

In response, the Victorian Department of Health implemented initiatives, including public awareness campaigns and improvements to health and emergency services, to be ready for future thunderstorm asthma events.

A network of pollen monitoring stations was also set up across the state to gather data that helps to predict future events.

A problem for decades

While this event was unexpected, it wasn’t the first time we’d had thunderstorm asthma in Australia – we’ve actually known about it for decades.

Melbourne reported its first instance of thunderstorm asthma back in 1984, only a year after this phenomenon was first discovered in Birmingham in the United Kingdom.

Thunderstorm asthma has since been reported in other parts of Australia, including Canberra and New South Wales. But it is still most common in Melbourne. Compared to any other city (or country) the gap is significant: over a quarter of all known events worldwide have occurred in Melbourne.

Why Melbourne?

Melbourne’s location makes it a hotspot for these kinds of events. Winds coming from the north of Melbourne tend to be dry and hot as they come from deserts in the centre of Australia, while winds from the south are cooler as they come from the ocean.

When hot and cool air mix above Melbourne, it creates the perfect conditions for thunderstorms to form.

Northern winds also blow a lot of pollen from farmlands into the city, in particular grass pollen. This is not only the most common cause of seasonal hay fever in Melbourne but also a major trigger of thunderstorm asthma.

Why grass pollen?

There’s a particular reason grass pollen is the main culprit behind thunderstorm asthma in Australia. During storms there is a lot of moisture in the air. Grass pollen will absorb this moisture, making it swell up like a water balloon.

If pollen absorbs too much water whilst airborne, it can burst or “rupture,” releasing hundreds of microscopic particles into the air that can be swept by powerful winds.

Normally, when you breathe in pollen it gets stuck in your upper airway – for example, your nose and throat. This is what causes typical hay fever symptoms such as sneezing or runny nose.

But the microscopic particles released from ruptured grass pollen are much smaller and don’t get stuck as easily in the upper airway. Instead, they can travel deep into your airways until they reach your lungs. This may trigger more severe symptoms, such as wheezing or difficulty breathing, even in people with no prior history of asthma.

So who is at risk?

You might think asthma is the biggest risk factor for thunderstorm asthma. In fact, the biggest risk factor is hay fever.

Up to 99% of patients who went to the emergency department during the Melbourne 2016 event had hay fever, while a majority (60%) had no prior diagnosis of asthma.

Every single person hospitalised was allergic to at least one type of grass pollen. All had a sensitivity to ryegrass.

Is thunderstorm asthma becoming more common?

Thunderstorm asthma events are rare, with just 26 events officially recorded worldwide.

However there is evidence these events could become more frequent and severe in coming years, due to climate change. Higher temperatures and pollution could be making plants produce more pollen and pollen seasons last much longer.

Extreme weather events, including thunderstorms, are also expected to become more common and severe.

In addition, there are signs rates that hay fever may be increasing. The number of Australians reporting allergy symptoms have risen from 15% in 2008 to 24% in 2022. Similar trends in other countries has been linked to climate change.

How can I prepare?

Here are three ways you can reduce your risk of thunderstorm asthma:

• stock up on allergy medication and set up an asthma action plan with your GP
• check daily pollen forecasts for the estimated pollen level and risk of a thunderstorm asthma event in your local area
• on days with high pollen or a high risk of thunderstorm asthma, spend less time outside or wear a surgical face mask to reduce your symptoms.

Kira Morgan Hughes, PhD Candidate in Allergy and Asthma, School of Life and Environmental Sciences, Deakin University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Ozempic and Wegovy are increasingly available in Australia and worldwide to treat type 2 diabetes and obesity.

The dramatic effects of these drugs, known as GLP-1s, on weight loss have sparked huge public interest in this new treatment option.

However, the risks and benefits are still being actively studied.

In a new study in Nature Medicine, researchers from the United States reviewed health data from about 2.4 million people who have type 2 diabetes, including around 216,000 people who used a GLP-1 drug, between 2017 and 2023.

The researchers compared a range of health outcomes when GLP-1s were added to a person’s treatment plan, versus managing their diabetes in other ways, often using glucose-lowering medications.

Overall, they found people who used GLP-1s were less likely to experience 42 health conditions or adverse health events – but more likely to face 19 others.

What conditions were less common?

Cardiometabolic conditions

GLP-1 use was associated with fewer serious cardiovascular and coagulation disorders. This includes deep vein thrombosis, pulmonary embolism, stroke, cardiac arrest, heart failure and myocardial infarction.

Neurological and psychiatric conditions

GLP-1 use was associated with fewer reported substance use disorders or addictions, psychotic disorders and seizures.

Infectious conditions

GLP-1 use was associated with fewer bacterial infections and pneumonia.

What conditions were more common?

Gastrointestinal conditions

Consistent with prior studies, GLP-1 use was associated with gastrointestinal conditions such as nausea, vomiting, gastritis, diverticulitis and abdominal pain.

Other adverse effects

Increased risks were seen for conditions such as low blood pressure, syncope (fainting) and arthritis.

How robust is this study?

The study used a large and reputable dataset from the US Department of Veterans Affairs. It’s an observational study, meaning the researchers tracked health outcomes over time without changing anyone’s treatment plan.

A strength of the study is it captures data from more than 2.4 million people across more than six years. This is much longer than what is typically feasible in an intervention study.

Observational studies like this are also thought to be more reflective of the “real world”, because participants aren’t asked to follow instructions to change their behaviour in unnatural or forced ways, as they are in intervention studies.

However, this study cannot say for sure that GLP-1 use was the cause of the change in risk of different health outcomes. Such conclusions can only be confidently made from tightly controlled intervention studies, where researchers actively change or control the treatment or behaviour.

The authors note the data used in this study comes from predominantly older, white men so the findings may not apply to other groups.

Also, the large number of participants means that even very small effects can be detected, but they might not actually make a real difference in overall population health.

Other possible reasons for these links

Beyond the effect of GLP-1 in the body, other factors may explain some of the findings in this study. For example, it’s possible that:

• people who used GLP-1 could be more informed about treatment options and more motivated to manage their own health
• people who used GLP-1 may have received it because their health-care team were motivated to offer the latest treatment options, which could lead to better care in other areas that impact the risk of various health outcomes
• people who used GLP-1 may have been able to do so because they lived in metropolitan centres and could afford the medication, as well as other health-promoting services and products, such as gyms, mental health care, or healthy food delivery services.

Did the authors have any conflicts of interest?

Two of the study’s authors declared they were “uncompensated consultants” for Pfizer, a global pharmaceutical company known for developing a wide range of medicines and vaccines. While Pfizer does not currently make readily available GLP-1s such as Ozempic or Wegovy, they are attempting to develop their own GLP-1s, so may benefit from greater demand for these drugs.

This research was funded by the US Department of Veterans Affairs, a government agency that provides a wide range of services to military veterans.

No other competing interests were reported.

Diabetes vs weight-loss treatments

Overall, this study shows people with type 2 diabetes using GLP-1 medication generally have more positive health outcomes than negative health outcomes.

However, the study didn’t include people without type 2 diabetes. More research is needed to understand the effects of these medications in people without diabetes who are using them for other reasons, including weight loss.

While the findings highlight the therapeutic benefits of GLP-1 medications, they also raise important questions about how to manage the potential risks for those who choose to use this medication.

The findings of this study can help many people, including:

• policymakers looking at ways to make GLP-1 medications more widely available for people with various health conditions
• health professionals who have regular discussions with patients considering GLP-1 use
• individuals considering whether a GLP-1 medication is right for them.

Lauren Ball, Professor of Community Health and Wellbeing, The University of Queensland and Emily Burch, Accredited Practising Dietitian and Lecturer, Southern Cross University

This article is republished from The Conversation under a Creative Commons license. Read the original article.