Spring is rightfully considered the peak season for hay fever sufferers in Canberra, though recent measurements of pollen and spores in the air show that late Summer and early Autumn can also be a sniffly time in the Capital. The Canberra Pollen and Spore Monitoring Program at the ANU has been measuring daily pollen counts throughout the year and the latest results show some surprisingly elevated levels of allergy causing pollen and spores in our air during the months of February and March.
Grasses are some of the biggest culprits when it comes to allergic rhinitis (hayfever and asthma), though throughout much of southern temperate Australia the peak season is over by December. In Canberra we are on the boundary between grasslands dominated by temperate species (such as Rye Grass) that flowers during the Spring and early Summer and the subtropical species (such as Buffalo Grass) that flower later around late January into February. That means we have the potential to experience a second hay fever season due to grasses. This year, however, we noticed that people were complaining of hay fever related symptoms (eyes, nose, throat and lungs) extending into early Autumn – suggesting that other factors might be playing a role in heightened allergic reactions (Fig. 1).
Figure 1. Climate, pollen and total symptoms reported for the months of February to March in Canberra, 2019. The daily pollen counts for the most abundant types include Chinese Elm, Casuarina, Grass and the , 18 Feb - 8 March) and the native Casuarina tree (26 Feb – 11March). In addition, the airborne spore gic rhinitis symptoms reported (AirRater.org study) standardised against the total survey participant numbers (period average depicted by black dashed line). The elevated level periods for each pollen/spore type are shown by coloured horizontal bars. The red shaded block shows the period when elevated pollen levels (multiple pollen types) coincide with of greater levels of hay fever symptoms in the survey population.
The daily pollen counts show that low levels of grass occurred throughout February, but these were accompanied by periods of elevated levels of the common allergenic tree pollens including Chinese Elm (Ulmus, 18 Feb - 8 March) and the native Casuarina tree (26 Feb – 11 March). In addition, the airborne spore Alternariashows elevated levels during three periods across these two months. The elevated levels of multiple allergenic pollens (Fig. 2) occurring at the same time is likely to lead to a much greater number of people experiencing mild to severe hay fever during these times (Fig. 3). Warm temperatures and an extended dry period from early February to mid-March (which included a major dust storm) appears to have led to an even longer period for hay fever sufferers in Canberra to endure the sniffles this year.
Figure 2. Dominant types of airborne pollen and spores recorded during the months of February and March in Canberra.
Figure 3. Box and whisker plots of total symptoms in periods of elevated and low pollen reported for the months of February to March in Canberra, 2019. Shows the greater number of sypmtoms related to hay fever recorded during periods of elevated ad multiple pollen present in the atmosphere.