How to manage the spring pollen surge

Either we are affected ourselves or we know someone who is – or soon will be – struggling with a runny nose and itchy eyes as pollen from grasses and trees begins to spread through the air. Therefore, we took the opportunity to ask a few questions to Christer Janson, Professor of Respiratory Medicine and Allergy at the Department of Medical Sciences and Consultant at Uppsala University Hospital.

What happens in the body when we develop a pollen allergy?

“The allergens, which are proteins, are initially taken up by immune cells. In some individuals, these begin to interact with so-called T helper cells (Th2 cells), which in turn signal to B cells to start producing what are known as IgE antibodies. Upon subsequent exposure to the same type of allergen – in this case, a form of pollen – the reaction becomes more pronounced due to a kind of immunological memory that recognises the substance as harmful. This triggers a process in which the body releases, among other things, histamines, and the classic symptoms begin to appear,” explains Christer Janson.

The intensity of the reaction depends on a range of factors, and it remains difficult to determine why some individuals are more severely affected than others.

“We do not fully understand why some react more strongly than others, but we can measure levels of IgE antibodies, and those with more severe symptoms usually have higher levels. Heredity is by far the most important factor in developing pollen allergy. However, we can also see that the environment plays a role: people living in cities tend to be more severely affected than those who grow up in rural settings, for example on farms. The latter appear to be exposed to allergens earlier and more frequently, which may make them more resilient.”

Itching – a clear sign

As the severity of symptoms vary, it can sometimes be difficult to determine whether pollen allergy is the cause.

“The key difference is that pollen allergy is clearly seasonal. If these problems recur at the same time each year, one can begin to conclude that pollen is the likely cause. A particularly clear symptom is itching, so that is something to look out for. Another practical tip is to take an antihistamine tablet – if your symptoms improve, you can be fairly certain it is an allergy.”

Are over-the-counter medicines the most effective option?

“That depends on the severity of the symptoms. Tablets are the simplest way to achieve relief. If symptoms are more severe, treatment should not only alleviate them but also address the underlying inflammation. This is usually done with cortisone for nasal symptoms and sodium cromoglicate for eye symptoms. We also have allergy vaccines – previously administered as injections, but nowadays tablets are available for grass pollen, tree pollen and house dust mites.”

Climate change – a driver of pollen levels

Although new and more convenient treatments have been developed for those most severely affected, there are indications that pollen levels in the air are unlikely to decrease. As the climate changes and average temperatures rise, the prevalence of pollen allergy has also increased.

“Looking at the period from the 1990s to around 2010, we observed a substantial increase in pollen allergy – roughly 10 per cent. We have linked this to higher concentrations of pollen in the air as a result of climate change,” says Christer Janson.

There is also a risk that new allergenic species may become established in Sweden.

“Yes, we already have examples of allergens becoming more common as the climate changes. In the United States, for instance, the plant ragweed has caused very severe allergic reactions, and there is a risk that it could establish itself in Sweden.”

A glimmer of hope in a new study

Despite these concerns, there are indications that the situation may be stabilising.

“A recent study, conducted in Norrbotten, followed three cohorts of eight-year-olds from 1996 to 2017. There was a significant increase between the first and second groups, but no increase at all between the second and third groups – that is, between 2006 and 2017. It may be that a plateau has been reached, although it is difficult to generalise. Nevertheless, it offers some hope,” concludes Christer Janson.

Robin Widing