Do human rhinovirus infections and food allergy modify grass pollen–induced asthma hospital admissions in children?

High ambient levels of grass, weed and other pollen are associated with asthma admissions in children and adolescents: A large 5‐year case‐crossover study

“…We did not have information on respiratory viruses or pollen sensitisation, which may be important on the pollen trigger pathways to asthma admissions. However, our Melbourne study showed consistent effects of grass as significant predictors of asthma exacerbation, even after adjusting for human rhinovirus and taking pollen sensitisation into account . Therefore, at least for grass, we are reasonably confident that our result is close to a true estimate of asthma hospitalization risk in children.…”

“…Although studies including our own have strengthened our understanding of the link between ambient pollen levels and childhood asthma hospitalizations, no study has examined different pollen types and their impacts over a long period only focusing on children and adolescents who have been admitted to hospital for asthma. Our earlier studies found significant associations between grass pollen in Melbourne and asthma admissions but over short period . Im et al assessed effects of only weed and ragweed pollen during the fall season on asthma admissions in children 0‐14 years of age.…”

“…With climate change, including changing extreme weather patterns, the allergenic effect of pollen is projected to increase, 10 especially in urban areas. 11 Although studies including our own have strengthened our understanding of the link between ambient pollen levels and childhood asthma hospitalizations, [12][13][14] no study has examined different pollen types and their impacts over a long period only focusing on children and adolescents who have been admitted to hospital for asthma. Our earlier studies found significant associations between grass pollen in Melbourne and asthma admissions but over short period.…”

“…Our earlier studies found significant associations between grass pollen in Melbourne and asthma admissions but over short period. 12,13 Im et al assessed effects of only weed and ragweed pollen during the fall season on asthma admissions in children 0-14 years of age. They found increases in 13 counts of weed pollen (per cubic metre) 3 days prior increased daily hospital admissions in this age group.…”

Does allergy explain why some children have severe asthma?

“…109 Pollen levels can vary considerably throughout the year, with levels up to 100 grains/m³ resulting in an increase in ED presentations of 18.8%. 34,110,111 Pollens are much larger than HDM and mould allergens and are more likely to be filtered out by the upper airway so less penetrates the lower airways. 109 Pollen allergy also demonstrates a synergistic relationship with viral infections, as respiratory viral infections are more likely to be associated with severe asthma exacerbations requiring hospitalization when ambient grass pollen concentrations are high.…”