# Pulmonary Function Tests in Thunderstorm-associated Respiratory Symptoms: A Cross-sectional Study

## TL;DR

This study found that most people with thunderstorm-related breathing issues don't show clear signs of lung blockage, but they are more likely to have reactive airways.

## Contribution

The study provides new evidence on the prevalence of bronchial hyperresponsiveness in thunderstorm-associated respiratory symptoms.

## Key findings

- 30.6% of thunderstorm-associated patients showed airflow limitation, similar to 33.3% in the non-thunderstorm group.
- Thunderstorm-associated patients had significantly higher positive methacholine challenge test results (81.72%) compared to the non-thunderstorm group (56.17%).
- Most thunderstorm-associated patients had no obvious airflow limitation in spirometry.

## Abstract

Epidemic thunderstorm asthma is an observed increase in cases of acute bronchospasm following thunderstorms. This study aimed to compare the frequency of obstructive airway disease or bronchial hyperresponsiveness in subjects with thunderstorm-associated respiratory symptoms with subjects with similar symptoms presented at other times.

A cross-sectional study from June to November of 2013 was conducted on subjects with thunderstorm-associated respiratory symptoms living in Ahvaz City, Iran. Thunderstorm-associated subjects were presented with asthmatic symptoms in thunderstorms, and other patients presented with similar symptoms at other times. Baseline spirometry was performed on patients to examine the presence of obstructive airway disease. In all patients with normal spirometry, a provocation test was applied. A comparison of qualitative and quantitative variables was made using
the Chi-square and independent t test, respectively. All analyses were carried out using SPSS Statistics Version 22. A P value less than 0.05 was considered statistically significant.

Out of 584 subjects, 300 and 284 participants were in thunderstorm-associated and non-thunderstorm-associated groups, respectively. After the final analysis, 87 (30.6%) and 89 (33.3%) of the thunderstorm-associated subjects and non-thunderstorm-associated group, respectively, had pieces of evidence of airflow limitation (P=0.27). Among the patients with normal spirometry, 161 (81.72%) of the thunderstorm-associated patients and 100 (56.17%) patients of the non-thunderstorm-associated symptoms group had a positive methacholine challenge test result (P<0.001).

Most of the patients with thunderstorm-associated respiratory symptoms had no obvious evidence of airflow limitation in spirometry.