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Will climate change make the effects of pollen worse?

Posted by: , Posted on: - Categories: Health in a changing climate

pollen plant

Many people feel the effects of pollen at this time of year, but did you know the way pollen affects our health could change as plants react to our changing climate?

Current pollen picture

Pollen grains are tiny particles produced by flowering plants for reproductive purposes; some plants transfer pollen to other flowers of the same kind by means of insects, while many rely on wind to carry pollen grains through the air to their destination.

Pollen contains proteins and a significant number of people have an allergic reaction to these proteins when they breath them in (most commonly hay fever, but also allergenic asthma and eczema).

In the UK it is estimated that every year millions of people feel the ill-effects of pollen exposure.

The pollen season in the UK has three distinct but overlapping phases:

  • Early in the year, from about March until May, the blossoming of trees such as Hazel and Birch creates the first wave of symptoms for some pollen allergy sufferers.
  • From May until July grass pollen forms the bulk of the UK’s pollen load
  • Weed pollen (such as dock and mugwort) starts to occur from June and can last well into the autumn.

The UK has a network of pollen monitoring stations, which essentially suck air laden with pollen particles into a device where sticky tape captures the pollen. The tape is then placed under a microscope and the pollen particles are counted.

What will climate change do to pollen patterns in the UK?

It’s likely a changing climate will impact pollen patterns in at least three ways

  1. A changing climate will mean changes in temperature and rainfall may lengthen the UK pollen season and potentially make pollen concentrations higher;
  2. It’s possible that climate change will lead to changes in the potency of pollen – a single pollen particle can have varying amounts of the allergy causing agent on it;
  3. The UK is also facing a threat from changes in the geographical distribution of allergenic plants, due to climate change, with invasive species such as ambrosia (common ragweed) being on the watch list. A single ragweed plant can produce a billion grains of pollen per season and its pollen causes strong allergic reactions.

Can research help hayfever/asthma sufferers?

PHE, the Met Office and several universities are researching various aspects of pollen.

An early result suggests that careful cutting regimes of grass could make a significant difference to the amount of grass pollen produced, with more work needed in this area to find out the health impact of such a change.

Looking to improve pollen forecasts using molecular genetics (i.e. DNA sequencing) will give more precise information to allergy sufferers, who already know which types of grass pollens affect them and when, so they can take appropriate action.

There is currently no easy way of distinguishing between the pollen grains produced by 150 species of grass, however understanding which species of grass pollens are in the air in high quantities at a particular time will allow people with hay fever and/or asthma to better manage their allergies and medication.

It may help people to discover which particular types of grass pollen they are reacting to.

Following on from a joint Met Office/PHE project, which produced species location maps of key allergenic plants for Cornwall, Devon and Somerset, further research has now expanded these maps for the whole of the UK.

The maps show the locations of key allergenic plants. They will be used by health researchers to study impacts of plants with allergenic pollen on hospital admissions for respiratory conditions, and also provide information to local authorities and healthcare practitioners and are useful as a tool to assist self-management or treatment of allergy sufferers.

It ‘s hoped that in the future these more detailed source maps can be used, alongside wind direction and precipitation patterns to provide more detailed and local warnings to sufferers, which pollen is impacting their area and in what concentrations.

Tackling pollen with data

The best thing the medical and research community can do is gather more information and then create systems which better inform the public when allergenic pollen levels are high.

Part of this work will involve expanding and improving links between universities and Government agencies’ working on pollen, and considering the Met Office pollen monitoring network with emphasis on greater geographic coverage and a move toward rapid automated or semi-automated techniques for pollen detection and identification.

Researchers can improve the quality of information about the type and seasonal occurrence of pollen that is provided to health care professionals, so that they can effectively plan treatment and clinical trials for remedies.

The medical and research community  can improve the dissemination of high quality information about the presence of pollen to the public via the media and patient organisations, so that sufferers can understand their symptoms, avoid exposure and manage medication if appropriate.

There are now smart-phone apps available which can help pollen sufferers by giving them individual forecasts and allowing users to feedback to the data providers, too.

There is also a need for strategies to monitor and where possible contain the spread of invasive species (such as ragweed), to minimise future pollen risks to the UK population.

We know there is research work still to be done and that we have good ideas about how climate change affects pollen release patterns and distribution in the UK; it’s important to act now to protect public health sooner rather than later.

Image: Clare Bell

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