Exposure to pollen during the first year of life increases the risk of respiratory systems, suggests a study published in Allergy: European Journal of Allergy and Clinical Immunology.¹

Researchers from Switzerland undertook a study to investigate the association of respiratory symptoms with pollen exposure during the first year of life. The effect of infants sex maternal atopy and air pollution on this association was also examined. The study enrolled 401 healthy full-term infants from the Basel-Bern Infant Lung Development cohort between January 2005 and January 2016. Respiratory symptoms (cough, dyspnea and wheezing) during the day and also at night were assessed by weekly telephonic calls all through the first year of life. These symptoms were evaluated on a five-category score with scores ranging from 0 to 4; higher scores indicating increasing severity of symptoms.

Overall, the respiratory symptom scores were low for the duration of the study. The mean symptom score was 0.13 for daytime respiratory symptoms and 0.12 for nighttime respiratory symptoms. Symptoms during the day were experienced over 3.92 weeks average, while the nighttime symptoms occurred over an average of 3.03 weeks.

Exposure to tree and grass pollen was associated with increased respiratory symptoms in infants, both during the daytime and nighttime. This association was noted for individual exposure to tree or grass pollen as well as combined exposure to both. The risk ratio per 10% increase in pollen/m3 for combined pollen exposure was 1.006, for tree pollen 1.005, while the RR for  grass pollen was 1.009 for daytime symptoms. For nighttime symptoms, the risk ratio per 10% increase in pollen/m3 for grass pollen was 1.014; for both combined pollen and tree pollen, the risk ratios were 1.003.

No correlation between combined pollen and maternal atopy or the infant’s sex was found. No interactions between PM2.5 or NO₂ and tree or grass pollen were noted. However, NO2 on its own was linked to respiratory symptoms.

This study has demonstrated for the first time that exposure to separate and combined exposure to tree and grass pollen increases respiratory symptoms during the first year of life even in healthy infants. Lungs are a vulnerable organ as they are still developing in infants. Exposure to pollen may increase the likelihood of the child developing chronic childhood asthma. The authors have called for further studies to better understand “the underlying mechanisms of the association between pollen and respiratory symptoms”.

Reference

1. Gisler A, et al; BILD study group. Pollen exposure is associated with risk of respiratory symptoms during the first year of life. Allergy. 2022 Mar 18. doi: 10.1111/all.15284.