Pollen exposure is one cause of asthma attacks for people prone to them. Breathing in pollen can also cause certain other respiratory symptoms such as sneezing, congestion, and a runny nose. Climate changing is constantly shifting pollen levels, changing the pollen season and in turn affecting human health. We often get the question: Can pollen be measured with sensors in real time? What kind of measurement technologies exist? What can be done to avoid pollen during its peak? Read on more to find out.

What is pollen?

Pollen is produced as part of the reproductive process of plants, specifically cone-bearing plants and flower-bearing plants. Cone-bearing plants produce pollen in pollen cores, while flower-bearing plants produce pollen in a section called anthers within the flower. 

Pollen grains have an adhering characteristic in order for insects visiting for nectar to pick them up and act as pollinators. Other methods of pollination include cross-pollination (pollen is carried to a flower of another plant to another species), self-pollination (a flower pollinates other flowers on the same plant), and wind pollination (release of pollen clouds into the air). Wind pollination is the main source of what causes all the allergy symptoms when the season peaks.

Pollen counts as particulate matter, but most intact pollen grains are larger than 10 μm. Hence, their concentrations often don’t show in particulate matter levels such as PM_2.5 or PM₁₀.

What are the health effects of pollen?

Pollen is one of the possible triggers of asthma attacks. People with hay fever (‘allergic rhinitis) can have symptoms such as sneezing, congestion, and runny nose from breathing in pollen. Other individuals can also experience allergic conjunctivitis, causing red, watery, or itchy eyes. 

Pollen also interacts with the immune system, particularly a certain number of cell types including:

• Epithelial cells – a type of cell that lines the surface of your body
• Dendritic cells – a long ‘tree-like’ cell that are responsible for the initiation of adaptive immune responses 
• Macrophages – special cells involved in the detection and destruction of bacteria and other harmful organisms
• Granulocytes – a common type of white blood cell

All of these cells have the potential to play a significant role in initiating and regulating airway inflammation following exposure to pollen. 

Furthermore, pollen grains interact with environmental pollutants; an ongoing research area between air pollution and cardiovascular and respiratory deaths. Traidl-Hoffmann and colleagues also state that environmental factors from natural and anthropogenic factors influence the aggravation and elicitation of allergic symptoms. This evidence is supported when a higher prevalence rate of allergies was shown in children regularly exposed to higher levels of urban air pollution exposure, especially to traffic emissions. 

Lastly, a time-series analysis in the Netherlands found a strong association between the day-to-day variation in pollen concentrations and deaths due to cardiovascular diseases. This supports the view that airborne pollen concentrations seem to have far more effects on human health than previously thought. 

How is climate change affecting pollen?

Why is pollen relevant and concerning? Increasing temperatures due to climate change cause shifts in seasons: milder autumn and winter, longer spring and summer times. This in turn starts the flowers to bloom earlier and for longer periods. Species of plants not previously native in the case of Germany are establishing from the rise in temperature. One such example is the ragweed (Ambrosia artemisiifolia), which originated in North America and came to Europe through globalization in trade.

These findings are also consistent with research done in North America by Paudel and colleagues. Upon analysis of pollen and mold concentrations in the San Francisco Bay area, there were ties between pollen seasons and observed climate variables. They also observed pollen and mold activities increasing outside their peak seasons, reasons being due to local change in land-use and rapid urbanization. 

How to measure pollen

 Several methods have been used to measure pollen around the world. Most of them are relying on manual sampling and sample analysis, however some new and innovative technologies are piloting autonomous or semi-autonomous pollen measurement systems. Here are some examples:

Melbourne pollen and count forecast (manual)

The Burkard spore trap is an air-sampling device that is used to catch airborne pollen on a glass slide, which is stained with a dye and counted using a microscope. Under the microscope, different types of pollen can be distinguished by a laboratory analyst in a manual process due to their unique shapes, color, and size. The daily pollen count is a report of both grass and all kinds of pollen (as grains per cubic meter of air) caught in the trap in the previous hours. The Melbourne pollen and count forecast also compiles a comprehensive website that provides more information on grass pollen count and other FAQs.

American Council on science and health (manual)

Rotorod, a silicone grease-coated clear rod that tests the air on a schedule, usually over a 24 hour period. The pollen covered on the rod is then examined and calculated into amounts from low to high that makes sense to the general public. A current pollen allergy forecast can be followed to observe critical points during the day.

German Research Center for Environmental Health (manual and automatic)

The German Pollen Information Service Foundation (PID) provides a German-wide measurement network consisting of 36 sites using the Hirst trap. The Hirst trap, also known as the Bukard trap, is a pollen measurement device that determines pollen through a pollen analyst using a microscope. Additionally, a new automatic pollen measurement technologie is being piloted in Germany: A new BAA500 pollen meter automatically captures microscopic images of pollen and compares them to samples from an image database. The PID also provides a number of services that provide daily and weekly pollen counts as well as how to adjust activities during high counts. 

How to avoid pollen

There are several actions you can take to reduce allergic reactions to pollen:

1. Avoid grassy areas such as parks and fields, particularly in the morning and evening when the pollen count is at its peak.
2. Change and wash outdoor clothes after being outside in order to prevent pollen entering your home. 
3. Keep windows closed at peak pollen times and ventilating with air conditioning also helps to prevent pollen in your home environment. 
4. Check weather reports for the pollen count and stay in-doors when advised to reduce outdoor activity, if possible.
5. With the relations of pollen and other air pollutants, monitoring environmental pollutants that can aggravate the symptoms of allergies is also an important step to be wary of.
6. Become a sensor host to bring real-time data information about other airborne pollutants right at your doorstep!