UKHSA issues unwelcome early warning over spring illness | Weather | News
The UK Health Security Agency (UKHSA) has issued an unwelcome early warning of a spring illness that could be triggered earlier this year thanks to a milder winter.
Studies suggest a warmer climate can result in some types of pollen being released sooner than normal, meaning hay fever can be triggered as early in the year as January or February. According to the Met Office, hay fever season typically kicks off in late March and lasts until September. Late March coincides with the start of astronomical spring, which is generally when weather conditions start to warm up. But Met Office data shows mean temperatures across the UK this winter were above the seasonal long-term average, with Southern England in particular seeing the warmest climes.
This February ranks as the ninth warmest on record for the UK, with all four nations recording above average mean temperatures last month, and these mild conditions can have a knock-on effect for the release of pollen.
In a warning posted on X this week, the UKHSA said: “Studies suggest that some types of pollen and other allergens could be released earlier in the year and for longer durations as the climate warms. This may mean that hay fever could be triggered as early in the year as January or February.”
Traditionally, the UK pollen season is split into three distinct, but overlapping, phases. The first phase usually runs from March to May with the release of tree pollen, followed by grass pollen from mid-May to July, and finally weed pollen is the last to be released from around July to September.
But pollen levels are very much dependent on weather conditions during spring and early summer, with warmer temperatures meaning more pollen is produced. Spring rainfall is also a big influence, as a dry season will reduce the amount of pollen production, but this winter ranks among the wettest on record for some parts of the UK.
Research suggests that with increasing temperatures, oak and grass pollen seasons may start even earlier, triggering hay fever symptoms as early as January or February.
The UKHSA added: “It’s likely a changing climate will impact pollen patterns in at least 3 ways:
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;
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.”
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The Met Office says the start of the hay fever season can also depend on where you live in the UK, with those based in the north tending to see a later start and a shorter season as there’s generally less pollen than in the south. Urban areas will also have a lower pollen count than in the countryside, and inland areas have higher levels than on the coast.
Hay fever symptoms occur when the pollen count (the number of pollen grains in one cubic metre of air) exceeds 50 and this will generally be worst in the early evening when the count is at its highest.
