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Allergy Today: Twelve-month Daily Pollen Forecasts for Aotearoa-New Zealand - and a note about pollen counting

Pollen forecasting for all 12 months of the year is now available on MetService New Zealand’s regional weather forecast pages. These can be found by visiting: https://www.metservice.com/towns-cities Screen Shot 2021-11-01 at 3

The service is an extension to the spring and summer forecasts we have seen for the past 24 years, which covered the main grass season. Now, the forecasts include winter, early spring and autumn months, as well as the heavy-pollen spring and summer periods.

The pollen forecast provides an indication of pollen abundance in the air, plus a listing of the pollen types predicted to be in the air at any location in New Zealand. Clicking on any city or region to obtain a local weather forecast, and scrolling down the page, will give you today’s pollen forecast indicating low/moderate or high exposure risk. It will also provide a list of pollen types predicted to be in the air.

The data is derived from 24 years of pollen season flowering timing records (phenological data) for New Zealand allergenic plants throughout the country. It is supported by four limited historical published pollen count studies.
The dramatic appearance of yellow dust in late winter, marks the arrival of a cloud of pine pollen that is the controlled shedding from flowering pine trees over a two to four week period each year.

This marks the start of the hayfever season. The macrocarpa, or cypress, is also allergenic to some and i
n this photo, we can see the author shaking a macrocarpa branch, which releases a cloud of pollen from the male cones of the tree.

This conifer burst is quickly followed by pollen from yellow-flowered wattle (Acacia). Wattle pollen is very large and shed as a fused cluster of individual grains that generally does not travel far on the wind.Macrocarpa Tree Picture-682

Pollen from deciduous trees, of which many people are allergic, quickly follow. These include hazelnut, alder, ash, elm, oak and maples. Birches follow these and the bright yellow pollen is released from the prominent catkins high in the trees. Compared to pine pollen, you won't notice these deciduous tree pollens as the grains are smaller and not released en masse as clouds of pollen, but are more potent in provoking allergy symptoms.


The months of September through to December are even more potent as grass pollen fills the air we breathe. Many of us find this period of the year difficult due to sneezing, a running nose and eyes, a scratchy throat, and for some, asthma.
The pollen forecast service will let you know which of these pollen types is likely to be in the air you breathe on any given day. Local pollen sources – such as a birch tree in your section, a shelter belt of pines upwind, or an area of grass flowering nearby - will vastly influence these general forecasts however, leading to increased density of pollen in the air you breathe.

Indication levels
‘Low’ means little or no pollen is forecast to be in the air on the reported day, meaning the pollen allergy hazard is low.
‘Moderate’ means significant allergenic pollen of those listed is likely to be about in your district and likely to cause significant inhalant allergy in sensitised people.
‘High’ means the combination of the listed plant pollen types and the prevailing forecasted weather will generate high pollen loads in the air and could cause severe allergy.
These designations refer to an assessed pollen allergy hazard level based on the following three inputs:

  • Pollen known to be in the air now in each location and its allergenicity
  • How the weather will affect production of pollen
  • How the weather will move the pollen from its sources in the anthers of plants, into the local or distant air.

The assessments are based on a combination of factors known to influence the production of pollen by allergy-causing plants, and the movement of the pollen in the air by the forecasted weather conditions. Some of the factors used in determining the level of pollen hazard, are the strength of the allergy-causing pollen type (technically known as its allergenicity); the estimated amount of pollen production; and altitude, temperature, wind dispersal, electrical, and rainout factors, all of which are known to depress or elevate pollen levels in the air.

Due to the geographical nature of Aotearoa, plant growth and development is affected by latitude, altitude, and climatic zones, which influence when pollen from each allergy-causing plant species is produced each year.

What about pollen counting for New Zealand?
Many countries overseas have well-developed networks of pollen counting stations in major cities and districts. These are particularly strong in Europe, Scandinavia, North America and Japan. Recently, there have been reports about the need for the establishment of similar stations here in New Zealand.

These could use automated, algorithm-assisted pollen identification systems that accurately determine the pollen content in the air, perhaps avoiding the labour-intensive methods used in the last 100 years, which carry high costs per station. I worked in a palynological laboratory in Stockholm where pollen counting was performed every day over the Swedish summer and can attest to the desirability of getting rapid, scientifically robust data to release to media.

Pollen counts are a quantitative measure of pollen density in the air (expressed as number of pollen grains per cubic metre of air). Establishing such a system here would yield data that would allow solid comparisons of our air with that of other countries. It would also aid inhalant allergy research and set baseline pollen data to allow tracking of possible changes due to environmental and agricultural trends, such as climate change and primary productivity.

Here, in New Zealand, this would require individual pollen counting stations for every location, bearing in mind the data obtained suffers from inaccuracies due to the time the pollen sampling was performed and just where the pollen sampling equipment is located. Most pollen stations around the world, however, are expensive to operate since trained technicians must use a sampling device, and manually count pollen grains under a microscope. Progress has been made in automating parts of this process by clever engineering, but more innovation is needed.

In the meantime, the MetService pollen forecast using phenological data based on what’s flowering and where will continue to aid people with pollen allergy and asthma in Aotearoa.

Remember, we all breathe the pollen-laden air in this country. Four out of five people have an immune system that tolerates this assault on our airways, but one in five will be sensitised to the protein allergens that flood out of the pollen grains when they become wet in our nose or on airway surfaces. These stimulate the allergic response resulting in a running nose, reddened eyes and irritated airways. To know if you are allergic to pollens, you should consult your GP to arrange a diagnostic test (usually a simple skin test).

More information about pollen and pollen allergy in Aotearoa available at:
https://blog.metservice.com/pollen and you can also refer to the Allergy NZ Pollen Calendar here.

Dr David Fountain
Pollen Forecaster in association with Metservice NZ
Associate Professor, Plant Biology (Retired)
Massey University

A CHALLENGE TO CLEVER INVENTORS!

Modern, real-time sampling of air and analysis using automated artificial intelligence (AI) would be a game-changer, providing hour-to-hour pollen count data. I would challenge a clever reader to develop a portable real-time air sampler to accomplish what a ‘coulter counter’ does in identifying and counting cell particles e.g. from blood passing through a narrow glass tube (it is so narrow, the cells, or pollen grains, are forced to pass in a line and therefore can be easily counted and identified). We already have the expertise to use computer-assisted identification of pollen types in New Zealand, we just need a machine that passes one cubic metre of air through the capillary tube system equipped with AI to achieve a real and instant pollen count!

Allergy Today, October 2021