Airborne pollens in Brisbane

Abstract

Airborne pollens were studied daily by gravity slides from February 1962 to June 1963. There were two main pollen periods: a minor one in early spring due mainly to conifers, and a major one in summer due mainly to grasses. Grasses were responsible for 65 % of the pollen grains counted. They were present from September to May and most abundant in December and January. The commonest grasses observed in flower were: Chloris gayana, November- March; Cynodon dactylon, September-April; Paspalum dilatatum, October-March; P. urvillei, October-February; Panicum maximum, October-April; Rhynchelytrum repens, October-April; Eragrostis tenuifolia, October-March; Digitaria didactyla, December-March; Themeda australis, September-December. Because of their prevalence, high pollen yield, and allergenicity, Chloris gayana and Cynodon dactylon probably constitute the greatest risk of pollinosis in Brisbane. The commonest tree pollens found were those of the Cupressaceae, Eucalyptus, and Casuarina; among the plants and weeds those of Compositae and Plantago. It is likely that pollen, although important in causing hay fever, is an uncommon cause of asthma because: (a) being mostly over 20μ in diameter, it would rarely penetrate to the bronchioles; (b) there is no clear correspondence between the seasonal distributions of pollens and asthma.