Pollen season can be a drag for hay fever sufferers, with new research suggesting the symptoms will last longer as climate change continues to unfold.
Scientists from the University of Utah analysed pollen counts collected by 60 stations across the US and Canada from 1990 to 2018.
Results suggest the pollen season starts on average 20 days earlier than it did around three decades ago.
It then appears to last an additional 10 days and features over a fifth (21%) more pollen, inevitably triggering more uncomfortable itching, sneezing and eye watering.
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Human-induced climate change may be to blame, by throwing a plant's "internal timing" out of sync so it produces pollen earlier in the year.
"The strong link between warmer weather and pollen seasons provides a crystal-clear example of how climate change is already affecting peoplesâ€™ health across the US," said lead author Dr William Anderegg.
Hay fever affects up to three in 10 adults (10% to 30%) and four in 10 (40%) children in the UK.
While just a nusiance for many, hay fever can lead to more severe viral infections and even A&E visits, the Utah scientists wrote in the journal Proceedings of the National Academy of Science.
It has also been linked to a reduced performance at school among children, possibly due to the allergy disturbing their sleep.
"A number of smaller-scale studies, usually in greenhouse settings on small plants, had indicated strong links between temperature and pollen," said Dr Anderegg.
"This study reveals connection at continental scales and explicitly links pollen trends to human-caused climate change."
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The scientists analysed the pollen counts of stations managed by the US National Allergy Bureau.
Nationwide, pollen counts were found to have increased by an average of 21%, with Texas and the Midwestern states being worst affected.
Tree pollen was also found to have risen more than that produced by other plants.
To better understand whether climate change may be the culprit, the scientists applied statistical analyses to the pollen trends against nearly two dozen temperature models.
The results suggest climate change alone may be responsible for around half of the pollen season lengthing and approximately 8% of its rising count.
By splitting the years into two periods, 1990 to 2003 and 2003 to 2018, the scientists found climate change's impact on increasing pollen counts is accelerating.
"Climate change isn't something far away and in the future," said Dr Anderegg. "It's already here in every spring breath we take and increasing human misery.
"The biggest question is, are we up to the challenge of tackling it?"
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