Blog & updates

23 September 2026

Climate change and allergies in Australia

A changing climate is already affecting people with hay fever and asthma in Australia. Longer pollen seasons, thunderstorm asthma, bushfire smoke and mould after floods all play a part. Some of this is well established, and some is still uncertain, particularly the Australian data. This article sets out what the evidence shows and practical steps that can reduce your risk.

Why Australia is exposed

Australians have high rates of allergy. In one large international study, Melbourne had the highest rate of hay fever of all the cities involved (about one in three adults) and the highest rate of allergy to grass pollen. Our grass pollen season is also driven strongly by weather: rainfall in winter and spring and the number of hot days both affect how heavy a season will be. This makes pollen exposure here sensitive to changes in climate.

Longer and heavier pollen seasons

Plants respond to warmth and to carbon dioxide. In controlled growth experiments, higher carbon dioxide levels increased the amount of pollen some grasses produce. The clearest long-term data come from North America, where pollen seasons between 1990 and 2018 started about 20 days earlier and pollen levels rose by about 21%. Researchers attributed a substantial part of the earlier start to climate change.

Australia has shorter pollen records, and our seasons vary a great deal from year to year, so a clear local trend has not yet been shown. Researchers expect climate change to alter pollen exposure here, but how much, and in which direction for each region, is not yet known.

Thunderstorm asthma

During grass pollen season, certain thunderstorms can trigger sudden asthma in large numbers of people at once. Pollen grains are swept up into the storm, absorb moisture and burst into tiny particles. The cold wind gusts ahead of the storm carry these particles down to ground level, where they can be breathed deep into the lungs.

On 21 November 2016, a thunderstorm in Melbourne led to 3,365 more respiratory presentations to Melbourne and Geelong public hospitals than expected, and contributed to 10 deaths. In a survey of people who went to emergency departments that night, only 28% had a current diagnosis of asthma. Most had hay fever. Whether climate change will make these events more frequent is uncertain, but more intense storms and heavier pollen seasons would both increase the risk.

In Victoria, the epidemic thunderstorm asthma season runs from 1 October to 31 December. Daily risk forecasts are published during this period.

Not just Melbourne: Wagga Wagga and the Riverina

Thunderstorm asthma is not only a city problem. Wagga Wagga, a community I have close ties to, had one of Australia's largest earlier events. On 30 to 31 October 1997, Wagga Wagga Base Hospital recorded 215 asthma presentations in 24 hours. The Riverina is surrounded by ryegrass pasture, and a study of inland NSW hospitals found that the ryegrass pollen season (mid-October to the end of November) made up only 17% of the year but accounted for more than half of the days with peak asthma presentations. Wagga Wagga had the sharpest peaks of all the towns studied.

Victoria's thunderstorm asthma forecast does not cover southern NSW. If you live in the Riverina and have hay fever or asthma, keep your treatment going through late spring, and be indoors with windows closed when storms roll in on high pollen days.

If you or someone with you has severe or worsening breathing difficulty, follow your asthma action plan and call 000.

Bushfire smoke

Fire seasons in south-eastern Australia are becoming longer and more severe. Smoke is an irritant rather than an allergen, but it can make asthma much worse and irritate the nose and eyes. During the 2019 to 2020 Black Summer fires, smoke was estimated to have caused 417 excess deaths, more than 3,000 hospital admissions for heart and lung problems, and 1,305 emergency department presentations for asthma across eastern Australia.

Floods, humidity and mould

Heavy rain and flooding can leave homes damp, and mould grows readily in these conditions. In people who are allergic to mould, the spores can trigger hay fever and asthma. Damp buildings can also worsen breathing symptoms in people without a mould allergy.

What you can do

• Treat hay fever properly, and start early. Many hay fever treatments work best when used every day, starting a few weeks before the pollen season. Ask your GP or pharmacist which is right for you.
• If you have asthma, keep it under control. Take your preventer as prescribed, carry your reliever, and make sure you have an up-to-date written asthma action plan.
• Do not ignore chest symptoms. Cough, wheeze, chest tightness or breathlessness in spring can be a sign of asthma, even if you have only ever had hay fever.
• Check the forecasts. In Victoria, the Melbourne Pollen Count and Forecast gives daily pollen levels, and the Victorian Department of Health publishes epidemic thunderstorm asthma risk forecasts. On high-risk days, try to be indoors with windows and doors closed before and during the storm.
• Reduce smoke exposure. On smoky days, stay indoors with windows closed and set any air conditioner to recirculate. A portable air purifier with a HEPA filter can help in one room. A well-fitted P2 or N95 mask gives some protection if you need to be outside.
• Deal with damp early. Fix leaks, ventilate bathrooms and laundries, and dry out any water damage as soon as possible.
• Ask about desensitisation. For people with significant grass pollen allergy, allergen immunotherapy (desensitisation) can reduce symptoms over time. It is a long-term treatment, usually taken for about three years. How well it works varies between people, and it is not suitable for everyone.

When to see an immunologist or allergist

A referral from your GP is worth considering if your hay fever is not controlled despite regular treatment, if your asthma worsens each spring or on smoky days, if you are unsure what is triggering your symptoms, or if you would like to discuss desensitisation. Allergy testing, interpreted alongside your symptoms, can help identify which pollens or moulds are relevant to you, which helps target treatment.

Last reviewed: September 2026. This article is general information and does not replace advice from your own doctor. Key sources: Victorian Department of Health, Epidemic Thunderstorm Asthma Program; Borchers Arriagada et al., Medical Journal of Australia 2020; Anderegg et al., PNAS 2021; Thien et al., Lancet Planetary Health 2018; Hayden and Muscatello, NSW Public Health Bulletin 2011; Beggs, Public Health Research & Practice 2018. For more information, see the ASCIA website at allergy.org.au.

23 September 2026

Adrenaline nasal spray: is it right for you?

Since July 2026, a needle-free adrenaline nasal spray has been available on the PBS for the emergency treatment of anaphylaxis. A common question is whether to switch from an adrenaline injector. The honest answer is that it suits some people well and others less so. It is worth a conversation with your immunologist or allergist before your next prescription.

What is it?

It is a small, ready-to-use device that sprays one dose of adrenaline into the nose, where it is absorbed through the lining of the nose into the bloodstream. There are two strengths: 1 mg for children aged 4 and over weighing 15 to 30 kg, and 2 mg for children and adults weighing 30 kg or more. As with injectors, it is prescribed in pairs so a second dose is available.

Does it work as well as an injector?

Approval was based mainly on studies measuring adrenaline levels in the blood and the body's response (such as heart rate and blood pressure) after the spray, compared with injected adrenaline. These studies were largely done in people who were not having anaphylaxis at the time. The results were comparable, and the spray has been in use overseas since 2024. Even so, there is far less real-world experience with it than with injectors, which have been used for decades. The Australasian Society of Clinical Immunology and Allergy (ASCIA) includes both as options for treating anaphylaxis.

Who might it suit?

• People who delay or avoid using an injector because of a fear of needles. Adrenaline works best when it is given early, so a device you will use without hesitation matters.
• Children aged 4 and over (15 kg or more), and parents, carers and teachers who feel uneasy about giving an injection.
• Teenagers and adults who often leave their injector at home because it is bulky. The spray is smaller and easier to carry.
• People who work or travel in places with variable climates. It is more stable with variations in temperature.

Who may it not suit?

• Children under 4 years or under 15 kg. The spray is not approved for them. An injector remains the right option.
• People with nasal polyps, previous nasal surgery, a past broken nose or other structural problems of the nose. People with these conditions were not well represented in the studies, so how well the adrenaline is absorbed is less certain.
• People who would prefer to stay with a device they know well. If you are confident with your injector and carry it reliably, there may be no reason to change.

If you have heart disease, high blood pressure, an overactive thyroid, diabetes, glaucoma, Parkinson's disease or are pregnant, let your doctor know. This applies to any form of adrenaline. It does not mean you should withhold adrenaline in an emergency.

What if my nose is blocked?

According to the product information, the spray can still be used if you have a cold, hay fever or a congested nose.

Important things to know if you switch

• You need a new ASCIA Action Plan. Each device type has its own plan. Your doctor will need to complete and sign a new one.
• Update your school, childcare or workplace. They will need the new plan, and staff will need training on the new device.
• Do not test or practise with a real device. Each one holds a single dose. Ask about a trainer device for practice.
• A second dose may be needed. If there is no improvement after 5 minutes, give a second device, ideally in the same nostril. An injector can also be used as a second dose if that is what is available.
• Always call 000 after giving adrenaline, even if symptoms improve. Follow the positioning advice on your Action Plan: lie flat, or sit with legs outstretched if breathing is difficult. Do not stand or walk.
• Check expiry dates and storage. Keep it out of direct sun, and do not refrigerate it.
• The device does not change your allergy. Avoiding your triggers and carrying your device at all times still matter just as much.

Why talk to your immunologist first?

The right device depends on your age and weight, your nose, other health conditions, who is likely to give the adrenaline, and where you spend your time. A good time to discuss it is at your next review or when your current devices are due for renewal. Bring your current devices and Action Plan with you.

Last reviewed: September 2026. This article is general information and does not replace advice from your own doctor. For more information, see the ASCIA website at allergy.org.au.