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Asthma epidemics caused by climate change look set to become more common

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Emergency services in Melbourne had never seen anything like the dramatic events of last November 21.

As a ­thunderstorm struck the city, ­thousands of people experienced respiratory problems and hospitals had their ­busiest night ever. Up to 8500 people are thought to have been treated for acute asthma in the 24 hours after the storm, with at least eight deaths recorded, included New Zealand father-of-four Sam Lau.

Thunderstorm asthma epidemics are nothing new, says Richard Beasley, an expert in respiratory medicine at the Medical Research Institute of New Zealand. “These events are well recognised,” he says. “Having said that, the greater extremes in weather events that are a consequence of global climate change suggest weather-related asthma attacks may be becoming more common.”

Melbourne’s outbreak is believed to be the first to result in fatalities, but two previous epidemics there in the 1980s also saw a surge in hospital admissions. A similar phenomenon struck Kuwait, where five people died after a freak storm late last year. And there have been reports of storm-related asthma in Italy, the UK, Canada and the US.

“These events could happen, and will have occurred here in New Zealand,” says Beasley. “They may go unrecognised unless they occur in a big city. They are due to ­thunder­storms sweeping up pollen grains and rupturing them to release tiny allergen particles, which are small enough to inhale. These penetrate deep into the lungs, where they cause an allergic reaction with swelling and narrowing of the airways, triggering an asthma attack. It’s for this reason that people allergic to rye grass are at risk, and that the epidemics occur during the rye-grass pollen season.”

Richard Beasley: use inhalers even when feeling well.

Rye-grass pollen grains can travel long distances on the wind, ­increasing people’s chance of ­exposure. They are a major cause of hay fever in spring and early summer, but are generally less of an issue in coastal areas. Melbourne has an expanse of grasses around the city and the thunderstorm asthma outbreak involved a combination of a very high pollen count with a sudden change in humidity and wind.

Although we can’t do anything to control the weather, we can learn from the Melbourne experience in terms of asthma management, says Beasley. “We know people with asthma are less likely to suffer symptoms during a thunderstorm if they are taking their preventive steroid inhaler medication, which controls asthma with regular use. So this reinforces the importance of regular inhaler use even when asthma sufferers feel well.”

Worldwide, the number of people with asthma is rising. In New Zealand, more than 460,000 of us – one in nine adults and one in seven ­children – take asthma medication. Many kids end up in hospital as a result of serious attacks, with Maori and ­Pasifika people, and those living in the most deprived areas, more likely to need medical ­attention. About 67 people a year die from asthma in this country.

Less-dramatic weather events can also influence the condition, in particular sudden or marked changes in temperature and humidity. “But if asthma symptoms are being caused by changes in the weather, it’s likely to indicate that the patient’s condition is not adequately controlled,” says Beasley.

His advice to sufferers is be aware of the factors that provoke your asthma and have strategies in place both for their avoidance and for what to do if attacks occur. This applies to not only weather events but also such things as medications – aspirin and ­ibuprofen, for instance – that might provoke asthma, as well as certain foods and work-related exposure.

Anyone who has asthma ­symptoms at least twice a week should consider taking preventive medication such as a low-dose steroid inhaler.

Research shows sufferers who have an asthma action plan control their condition better than those who don’t. The Asthma and Respiratory Foundation recently released new action plans for adults, which it urges people to fill in with their GP.

Cases of thunderstorm asthma can occur in people with no history of the condition. Sufferers of hay fever caused by an allergy to grass pollen are thought to be at greater risk, so it’s important for them to recognise the symptoms of an asthma attack, which include wheezing (a whistling sound coming from the chest, especially when breathing out), breathlessness, chest tightness and severe coughing.

This article was first published in the February 25, 2017 issue of the New Zealand Listener. Follow the Listener on Twitter, Facebook and sign up to the weekly newsletter.