Teachers, keep the windows open: Hay fever linked to humid classrooms

Schools have been advised by medical experts to keep windows opened regularly and to introduce mechanical ventilation and dehumidification with the aim of decreasing conditions which contribute to allergies in children.

Students in poorly ventilated classrooms with higher temperatures and humidity are more likely to suffer from allergic rhinitis symptoms (hay fever), according to a study published in the Malta Medical Journal.

Increased classroom temperatures and humidity were also associated with increased incidence of allergic conditions in schoolchildren in Malta.

One possible reason for this phenomenon is that warm or humid classrooms increase the growth of bacteria and fungi which contribute to these allergies.

The study was authored by a cross-disciplinary team consisting of Caroline Gouder, Stephen Montfort and Peter Fsadni from the Department of Respiratory Medicine, Claudia Fsadni from the Department of Infectious Diseases, and Frank Bezzina from the Faculty of Economics.

The study was based on research conducted in five primary State schools in Malta, selected randomly from five geographical clusters.

These comprised Fgura, Birzebbuga, Pembroke, Qormi and Dingli. Three classrooms within each school were selected with all students being asked to participate. A total number of 237 pupils in all 15 selected classrooms consented to taking part in the study.

The study found that 32.98% of all the pupils had wheezing at one time in their life while 17.8% had experienced wheezing in the previous 12 months. Up to 16.8% of all pupils actually had doctor-diagnosed asthma.

Hay fever symptoms were present in nearly 34% of the children. 40% complaining of a runny nose and nasal phlegm, while half of the pupils complained of a blocked nose.

According to international standards, indoor relative humidity levels should ideally range between 30% and 70%. While the average humidity level within local schools falls within this range (62.71%), all three classrooms in Dingli exceeded the 70% threshold. All five schools had a relative indoor humidity above the mean of 43% found in schools across Europe.

The higher humidity levels detected in Dingli could have reflected meteorological conditions as the sampling in this particular case took place in December.