Vegetation, Air Pollution, and Asthma and Allergy: A Narrative Review

Abstract

Vegetation may benefit asthma and allergy, but null and detrimental associations were also reported. One explanation can be the impact of air pollution. The author aimed to narratively review published epidemiological studies that considered both vegetation and air pollution in relation to asthma, rhinitis, sensitization, and eczema. Search of peer-reviewed original studies was performed in PubMed. Additional articles were identified from the reference lists, the author's personal records, and new publication alerts. Among 18 identified studies, two indicate that vegetation reduces air pollution and is therefore protective against asthma. Results of three studies indicate that protective effects of vegetation on asthma are due to absence of pollution. Four studies identified varying interaction between vegetation and air pollution with allergic outcomes. The remaining studies reported no interplay between vegetation and air pollution in relation to allergy. Combined effects of air pollution and vegetation on allergic outcomes need to be further tested.