24 November 2022

Pollen-related asthma in kids needs yearlong vigilance

Asthma Paediatrics

Autumn, not spring, is the riskiest period for children with pollen-related asthma.


Children with pollen-related asthma are at greater risk of attacks in cooler months of the year, according to new Adelaide-based research.

The prevalence of asthma, commonly triggered by pollen particles in the air, is on the rise in Australia. This is particularly true for South Australia, where the prevalence has increased from 10.6% in 2015 to 13% in 2018.

This trend, combined with recent findings published in BMJ Open, has prompted calls for constant vigilance throughout the year rather than solely in spring.

The retrospective observational study used 15 years of hospital admission, emergency presentation, ambulance callout and daily pollen count data (categorised as grasses, trees and weeds) to estimate changes between the amount of pollen in the air and an asthma-related health outcome for children and adults on a month-by-month basis.

“The use of year-round pollen data avoids a restriction to a single season, which has been used in most studies,” the authors wrote.

Between 2003 and 2017, around 22,000 hospitalisations, 40,000 emergency presentations and 4000 ambulance callouts were attributed to asthma in under-18s in metropolitan Adelaide. Regional areas of South Australia were not included in the current study due to a lack of available pollen data.

Children and teens were at a greater risk of an asthma-related hospitalisation, emergency presentation or ambulance callout between February and May. For weed pollen, children had twice the rate of having an asthma-related ambulance call out in February, and around a 25% greater chance of emergency presentations in March and hospitalisation in April.

They were also 15% more likely to have a grass pollen asthma-related emergency presentation in May.

For adults, there were around 10,000 hospitalisations, 26,000 emergency presentations and 12,000 ambulance callouts over the same period.

In contrast to children, adults were at the greatest risk of having an asthma-related event during the warmer months. Adults had a 65% higher rate of ambulance callouts in February for weed pollen and 31% higher rate of ED presentations in October, when grass pollen was considered.

There was no association between asthma outcomes and tree pollen in the adult cohort.

Age-related decreases in symptoms of allergic asthma may explain why adults do not respond to tree pollen in the same fashion as children.

Annual asthma campaigns in South Australia typically kick off in September, with a focus on encouraging compliance with asthma preventer medications. Uptake of such messaging is typically greater in children due to higher rates of asthma diagnoses in this cohort compared to adults.

“Based on the results of our study, the asthma awareness campaign in Adelaide should start in August and continue until November, to help children and parents to be equally prepared for pollen exposure,” the authors said.

However, staying alert throughout the year could have greater benefits.

“[There is] a need for year-round pollen monitoring and related health campaigns to provide effective public health prevention,” they wrote. 

BMJ Open 2022, online 22 November