Ah, spring, the sun shines again, the birds sing and - ach-hoo! Airborne grass pollens trigger bouts of hay fever and episodes of asthma in people with pollen allergies.
But there is a way we could mitigate the impact of the season - pollen counts. These work in the same way as summer UV alerts, by telling us when there’s enough of something around to cause health harms.
And this helps manage the impact of UV or pollen by giving us time to prepare, by wearing UV protection, for instance, or taking antihistamines. But while this sounds like a good idea, most places in Australia don’t have a pollen count, so those of us with allergies are left to our own devices.
Pollen and health
Let’s talk first about how pollen affects health. Hay fever is the most obvious example.
According to the 2007–08 National Health Survey, hay fever affects one in six Australians, severely impairing their quality of life by making sleep difficult and causing them to under-perform at work or school.
Hay fever is strongly associated with asthma; more than 80% of allergic asthmatics also have hay fever. Asthma costs the Australian community over $700 million annually and this impact has made it one of the country’s national health priorities.
Asthma and hay fever are caused by our immune systems responding inappropriately to substances in the environment that are not harmful. These are known as triggers.
Hay fever triggers cause the lining of the eyes, nose and throat to become inflamed, producing the typical symptoms of sneezing, itchy eyes and a runny nose. Asthma triggers cause the lining of the small airways of the lung to swell, making it harder to breath.
Free like the wind
Pollen from certain wind-pollinated plants is the main asthma and hay fever trigger in the outdoor environment. The plants in question use wind to transport their pollen between plants, rather than relying on insects and birds.
Because they don’t need to attract animals, the flowers of wind-pollinated plants are rather dull in comparison to the bright, showy flowers of animal-pollinated plants.
But what they lack in colour, wind-pollinated plants more than make up for with prodigious pollen production. A single plant can release untold millions of pollen grains into the air.
While Australia’s native plants are generally not wind-pollinated, many introduced plants are. These include trees from the northern hemisphere commonly found in gardens and along suburban roads, such as birch, elm, and ash.
But the worst plants by far for pollen allergies are grasses. Perennial ryegrass is a valuable pasture grass planted across vast areas of southern Australia. By sheer weight of numbers perennial ryegrass pollen is Australia’s number one outdoor allergy trigger.
Flowering of perennial ryegrass across much of southern Australia peaks in November. And it’s no coincidence this is also the peak time for sales of the oral antihistamines.
Pollen counting can tell us how much grass pollen is in the air on a particular day. By combining this information with the weather forecast, we can predict grass pollen levels for the next few days.
Knowing the grass pollen forecast can help people allergic to grass pollen plan ahead. But before you can forecast pollen levels for a particular place, you need to have a few seasons’ worth of counts under your belt so you know how weather patterns affect pollen levels locally.
Unfortunately, Australia has very few pollen counting stations and most operate only sporadically. The lonely exception is Melbourne’s pollen count, which has been running consistently for over 20 years.
This makes a stark contrast with Europe, where a network of more than 600 pollen counting stations operates throughout the northern allergy season. That’s from early spring, when the trees flower, through to early autumn when weeds, such as dock and mugwort, flower.
The network operates efficiently across several countries and languages. And a similarly large network of stations operates across North America.
Australia’s lack of a pollen count network is surprising and means we often guess at things we really should know. For instance, we suspect Australia’s allergy season will be relatively simple to track compared to Europe’s, as we mainly have to contend with grass pollen.
But subtropical grasses that flower in summer are abundant in northern parts of Australia adding to the burden of hay fever. Right now, we don’t have a way of quantifying their role in the hay fever and asthma experienced by the population.
Knowledge and the power to help
Melbourne’s pollen data has been vital for understanding how grass pollen in the air influences hospital admissions for asthma. It seems ridiculous that we don’t know this for all Australian cities.
Not only do we need a network to monitor pollen, we need to be able to link it with weather forecasts for it to become a predictive tool.
On November 25, 2010, Melbourne’s ambulance service was overwhelmed with a massive number of calls from people with acute respiratory problems because of thunderstorm asthma.
Thunderstorm asthma occurs when there’s a thunderstorm during a high pollen count period. Prediction of pollen-induced epidemics of thunderstorm asthma could help hospital emergency departments prepare for such events.
This is only one of the many ways a national pollen count network could help improve public health throughout Australia. We just need to join the rest of the developed world and start gathering data that can inform us about what to do.