Association of asthma exacerbations with paper mulberry (Broussenetia papyrifera) pollen in Islamabad: an observational study

Osman Mohammad Yusuf, Aimal Tariq Rextin, Bakhtawar Ahmed, Rubina Aman, Tanveer Anjum, Saqib Mustafa, Mehwish Nasim, Shahida O Yusuf, Chun Lin, Summan Zahra, Hilary Pinnock, Jürgen Schwarze

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

BACKGROUND: The role of airborne plant pollen in causing allergic rhinitis has been established, but the association of concentrations of paper mulberry (Broussenetia papyrifera) pollens and incidence of asthma exacerbations has not been established, despite an observed increase in the number of asthma patients attending physician clinics and hospital Accident and Emergency (A&E) departments during the paper mulberry pollen season.

OBJECTIVE: To assess the association between paper mulberry pollen concentrations (typically peaking in March each year) and asthma exacerbations in the city of Islamabad.

METHODS: We used three approaches to investigate the correlation of paper mulberry pollen concentration with asthma exacerbations: 1) Retrospective analysis of historical records (years 2000 to 2019) of asthma exacerbations of patients from the Allergy and Asthma Institute, Pakistan (n=284); 2) Analysis of daily nebulisations in patients attending the A&E Department of the Pakistan Institute of Medical Sciences (March 2020 till July 2021); 3) Prospective peak expiratory flow rate (PEFR) diary from participants (n=40) with or without asthma and with or without paper mulberry sensitisation (based on skin prick testing). Association between pollen data and asthma exacerbations were examined by Pearson’s correlation.

RESULTS: 1). A strong positive correlation was found between mean paper mulberry pollen counts and clinical records of asthma exacerbations in patients who were sensitised to paper mulberry (Pearson’s r = 0.86, p < 0.001), but not in non-sensitised patients (r = 0.32, p = 0.3). 2) There was a moderate positive correlation between monthly nebulisation counts and pollen counts (r = 0.56, p = 0.03). 3) A strong negative correlation was observed between predicted PEFR and pollen counts in sensitised asthma patients (r = -0.72, p < 0.001) while these correlations were only of low magnitude in the non-sensitised asthma (r = -0.16, p < 0.001) and sensitised non-asthma (r = -0.28, p < 0.001) groups.

CONCLUSIONS: Our three approaches to analysis all showed an association between high paper mulberry pollen concentration in Islamabad and asthma exacerbations. Predicting pollen peaks could enable alerts and mobilise strategies to proactively manage these peaks of asthma exacerbations.
Original languageEnglish
Article number04091
Number of pages11
JournalJournal of Global Health
Publication statusPublished - 1 Sept 2023

Keywords / Materials (for Non-textual outputs)

  • Asthma
  • Pollen asthma
  • Paper mulberry
  • Pollen
  • Pollen allegy
  • Seasonal asthma
  • Islamabad


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