Short-term exposure to pollen and the risk of allergic and asthmatic manifestations: a systematic review and meta-analysis

Abstract

BackgroundSeveral studies have assessed effects of short-term exposure to pollen on allergic and asthmatic manifestations. The evidence is inconclusive, and no meta-analysis has been published.ObjectiveTo synthesise the evidence on the relations between short-term pollen exposure and the risk of allergic and asthmatic manifestations.MethodsWe performed a systematic literature search of PubMed and Scopus databases up to the end of August 2018. In addition, we reviewed the reference lists of relevant articles. Two authors independently evaluated the eligible articles and extracted relevant information in a structured form. We calculated summary effect estimates (EE) based on the study-specific ORs and regression coefficients (β) by applying both fixed-effects and random-effects models.Results26 studies met the a priori eligibility criteria, and 12 of them provided sufficient information for the meta-analysis. The summary EE related to 10 grains per m³ increase in pollen exposure showed an 1% increase (EE 1.01, 95% CI 1.00 to 1.02) in the risk of lower respiratory symptoms and a 2% increase (EE 1.02, 95% CI 1.01 to 1.03) in the risk of any allergic or asthmatic symptom. Correspondingly, the risk of upper respiratory symptoms and ocular symptoms increased 7% (EE 1.07, 95% CI 1.04 to 1.09) and 11% (EE 1.11, 95% CI 1.05 to 1.17), respectively, in relation to such pollen exposure. Short-term exposure to pollen did not show any significant effect on daily lung function levels.ConclusionOur results provide new evidence that short-term pollen exposure significantly increases the risks of allergic and asthmatic symptoms.

Exposure to green space and pollen allergy symptom severity: A case-crossover study in Belgium

“…The patients in our cohort are sensitized to birch pollen and thus experience more severe allergy symptoms when exposed to higher densities of Betula trees. The meta-analysis of Kitinoja et al (2020) confirmed that short term exposure to pollen was associated to an increase in allergic and asthmatic symptoms. On the other hand, we found that Alnus density was inversely associated with severe allergy.…”

Airborne pollen concentrations and daily mortality from respiratory and cardiovascular causes

“…Exposures to pollen from certain trees, grasses and herbs have been associated with some symptoms and signs of allergic reactions among subjects with asthma and allergies. 1 These effects are linked to type I allergic sensitization, which is mediated by specific IgE antibodies in the eyes and upper and lower airways. 2 Daily variation of pollen associates with exacerbations of asthma, and with daily outpatient visits and hospitalizations attributable to asthma and chronic obstructive pulmonary disease (COPD).…”

“… 2 Daily variation of pollen associates with exacerbations of asthma, and with daily outpatient visits and hospitalizations attributable to asthma and chronic obstructive pulmonary disease (COPD). 1 , 3 , 4 …”

Outdoor pollen concentration is not associated with exercise‐induced bronchoconstriction in children

“…However, studies have not managed to show that pollen concentrations have significant correlation with the change of lung function tests in all sorts of pollens. [35][36][37] In a Swedish study, 35 | 699…”