On the causes of variability in amounts of airborne grass pollen in Melbourne, Australia.
In Melbourne, Australia, airborne grass pollen is the predominant cause of hay fever (seasonal rhinitis) during late spring and early summer, with levels of airborne grass pollen also influencing hospital admissions for asthma. In order to improve predictions of conditions that are potentially hazardous to susceptible individuals, we have sought to better understand the causes of diurnal, intra-seasonal and inter-seasonal variability of atmospheric grass pollen concentrations (APC) by analysing grass pollen count data for Melbourne for 16 grass pollen seasons from 1991 to 2008 (except 1994 and 1995). Some of notable features identified in this analysis were that on days when either extreme (>100 pollen grains m(-3)) or high (50-100 pollen grains m(-3)) levels of grass pollen were recorded the winds were of continental origin. In contrast, on days with a low (<20 pollen grains m(-3)) concentration of grass pollen, winds were of maritime origin. On extreme and high grass pollen days, a peak in APC occurred on average around 1730 hours, probably due to a reduction in surface boundary layer turbulence. The sum of daily APC for each grass pollen season was highly correlated (r = 0.79) with spring rainfall in Melbourne for that year, with about 60% of a declining linear trend across the study period being attributable to a reduction of meat cattle and sheep (and hence grazing land) in rural areas around Melbourne. Finally, all of the ten extreme pollen events (3 days or more with APC > 100 pollen grains m(-3)) during the study period were characterised by an average downward vertical wind anomaly in the surface boundary layer over Melbourne. Together these findings form a basis for a fine resolution atmospheric general circulation model for grass pollen in Melbourne's air that can be used to predict daily (and hourly) APC. This information will be useful to those sectors of Melbourne's population that suffer from allergic problems.
de Morton
Julian
J
School of Earth Sciences, University of Melbourne, Melbourne, Victoria, Australia.
Bye
John
J
Pezza
Alexandre
A
Newbigin
Edward
E
D000485:Allergens / Q000009:adverse effects / Q000032:analysis*; D000704:Analysis of Variance; D000822:Animal Husbandry; D000818:Animals; D001249:Asthma / Q000209:etiology; D002417:Cattle; D002940:Circadian Rhythm; D018556:Crops, Agricultural; D006801:Humans; D008685:Meteorological Concepts; D052638:Particulate Matter / Q000009:adverse effects / Q000032:analysis; D006109:Poaceae / Q000009:adverse effects / Q000276:immunology; D011058:Pollen / Q000009:adverse effects*; D012621:Seasons; D012756:Sheep; D014739:Victoria
D000485:Allergens; D052638:Particulate Matter
Thorax. 2006 Apr;61(4):276-8
16565264
Clin Exp Allergy. 1993 Nov;23(11):911-8
10779278
Int J Biometeorol. 2008 Nov;52(8):805-14
18651182
Med J Aust. 1979 May 19;1(10):426-9
470669
Allergy. 2007 Sep;62(9):976-90
17521313
J Allergy Clin Immunol. 2002 Jan;109(1):51-6
11799365
Lancet. 2006 Aug 26;368(9537):733-43
16935684
Clin Exp Allergy. 1999 Mar;29(3):347-56
10202342
Clin Allergy. 1973 Sep;3(3):263-7
4778073
Clin Exp Allergy. 1993 May;23(5):354-9
8334534
Clin Exp Allergy. 2007 Nov;37(11):1641-7
17877763
Int J Biometeorol. 2004 May;48(4):172-8
14997370