Pollen may increase wheeze in children
11 March 2009

Exposure to high levels of pollen and fungal spores during the first months of life can boost a child's risk of being wheezy, according to researchers.

While previous research has suggested a child's risk of asthma varies according to the month of birth, few studies have looked at whether this could be linked to increased levels of airborne allergens such as pollen and fungal spores.

Californian researchers followed 514 children from birth until the age of 24 months, and found a clear pattern between asthma, wheeze and birth month.

The researchers found that children born between mid-February to March 2000 and between late August 2000 to early January 2001, trebled their risk of wheezing before the age of two compared to those born outside this period. In the Mediterranean-like climate of California, these months are when levels of outdoor fungal spores reach their peak. High levels of pollen in the air during a child’s first three months of life were also associated with an increased risk of wheeze.

Thirty-five children in the study (6.8 per cent) were diagnosed with wheeze by the age of two. Factors such as environmental tobacco smoke, poverty, and lower respiratory tract infections during the first year of life all increased the risk of early wheezing.

Dr Kim Harley, of the Centre for Children’s Environmental Health Research at California University, said: ‘Numerous studies have found the month of birth to be associated with the risk of allergic sensitisation or asthma later in life - an observation suggesting exposure to seasonal allergens in the perinatal period may contribute to the development of allergies.

‘Children with higher exposure to spores and pollen in the first three months of life are at increased risk of early wheezing.’

Dr Elaine Vickers, Research Relations Manager at Asthma UK said: ‘Although these results are interesting, it’s important to remember that this was a relatively small study conducted amongst a very specific group of people. The researchers were also unable to examine the children’s exposure to viruses, making it difficult to draw strong conclusions regarding the effects of pollen and fungi.

‘However, we do know that fungi and pollen trigger symptoms in many people with asthma and they should avoid these triggers wherever possible. One way of doing this is to keep your house dry and well ventilated as this will reduce your exposure to fungal spores, which are found in damp places.’