- Allergy or asthma symptoms increase by 2% on short-term exposure to pollen, but with no effect on lung function, according to this meta-analysis of 12 studies.
Why this matters
- This is the first meta-analysis of its kind amid conflicting results from individual studies.
- Worldwide, approximately 500 million suffer from allergic rhinitis and more than 300 million have asthma.
- A meta-analysis of 12 cohort studies after a search of PubMed and Scopus databases.
- Short-term was defined as 10 grains/m3 increase in pollen exposure.
- Funding: The Academy of Finland; others.
- Short-term pollen exposure was associated with:
- 1% increase in the risk for lower respiratory symptoms (effect estimate [EE], 1.01; 95% CI, 1.00-1.02);
- 2% increase in the risk for any allergy or asthma symptom (EE, 1.02; 1.01-1.03);
- 7% increase in the risk for upper respiratory symptoms (EE, 1.07; 1.04-1.09);
- 11% increase in ocular symptoms (EE, 1.11; 1.05-1.17); but
- No increase in daily lung function levels by spirometry.
- Small number of studies.