Regional and seasonal variation in airborne grass pollen levels between cities of Australia and New Zealand

Abstract

Although grass pollen is widely regarded as the major outdoor aeroallergen source in Australia and New Zealand (NZ), no assemblage of airborne pollen data for the region has been previously compiled. Grass pollen count data collected at 14 urban sites in Australia and NZ over periods ranging from 1 to 17 years were acquired, assembled and compared, revealing considerable spatiotemporal variability. Although direct comparison between these data is problematic due to methodological differences between monitoring sites, the following patterns are apparent. Grass pollen seasons tended to have more than one peak from tropics to latitudes of 37°S and single peaks at sites south of this latitude. A longer grass pollen season was therefore found at sites below 37°S, driven by later seasonal end dates for grass growth and flowering. Daily pollen counts increased with latitude; subtropical regions had seasons of both high intensity and long duration. At higher latitude sites, the single springtime grass pollen peak is potentially due to a cooler growing season and a predominance of pollen from C3 grasses. The multiple peaks at lower latitude sites may be due to a warmer season and the predominance of pollen from C4 grasses. Prevalence and duration of seasonal allergies may reflect the differing pollen seasons across Australia and NZ. It must be emphasized that these findings are tentative due to limitations in the available data, reinforcing the need to implement standardized pollen-monitoring methods across Australasia. Furthermore, spatiotemporal differences in grass pollen counts indicate that local, current, standardized pollen monitoring would assist with the management of pollen allergen exposure for patients at risk of allergic rhinitis and asthma.

A prognostic pollen emissions model for climate models (PECM1.0)

“…Trends for grass in Australasia show that the correlation of the end date of the pollen season with average spring temperature is positive, while the same relationship for the start date is negative, suggesting also that season start dates are earlier and season duration increases with warmer climates (Medek et al, 2016). The apparent trend in the season end date for Ambrosia with PYAAT could be due to the increased number of frost-free days, consistent with global warming, and a strong relationship between frost-free days and changes of ragweed season length (Easterling 2002;Ziska et al, 2011).…”

“…Observations by Craine et al (2012) of Poaceae in an American prairie have indicated that C 3 and C 4 grass flowering occurs at distinctly different times, with C 3 in the late spring and C 4 in mid-to-late summer. Similarly, Medek et al (2016) observed two grass pollen peaks in Australia, with a stronger, late-summer peak at lower southern latitudes where there is higher incidence of C 4 grass. However, the authors note that sometimes this may be due to a second flowering of some C 3 grass species.…”

High Levels of Allergenic Tree Pollen in Southern New Zealand

“…With the exception of the Palmerston North study of pine pollen, none of these papers focused on tree pollen. Recently, a series of publications have reviewed the available information about allergenic pollen levels in Australia and New Zealand and highlighted the emphasis placed to date on grass pollen [12][13][14][15]. As such, little is known about the levels of tree pollen in New Zealand, nor the extent to which such pollens could be contributing to the burden of allergenic rhinitis in New Zealand.…”

Biogeographical variation in specific IgE recognition of temperate and subtropical grass pollen allergens in allergic rhinitis patients

“…GP has been identified as the leading trigger of the most severe thunderstorm‐related asthma outbreak globally, including the most recent and fatal occurring in Melbourne, Australia, in 2016, with 10 related deaths . Both temperate and subtropical grasses are found in places with diverse climatic regions such as parts of Australia, Africa, India and America (Supplementary figure 1). Research has indicated differences in allergen composition and immune recognition between the pollen of grasses from different subfamilies .…”