Pollen calendar: Tracking airborne pollen to prevent allergy

Indian Express

Pollen grains are male biological structures with the primary role of fertilisation, but when inhaled by humans, they may strain the respiratory system and cause allergies.

By studying airborne pollen and its seasonal variations for about two years, researchers from the Post Graduate Institute of Medical Education and Research (PGIMER) and Panjab University have created a pollen calendar for Chandigarh, arguably the first for any city in India.

Titled, ‘Pollen calendar to depict seasonal periodicities of airborne pollen species in a city situated in Indo-Gangetic plain, India’, the study was recently published in the journal Atmospheric Environment.

Dr Ravindra Khaiwal, Additional Professor of Environmental Health, Department of Community Medicine and School of Public Health, PGIMER, the lead investigator of the study, spoke to The Indian Express to explain this pollen calendar and its role in preventing allergies.

What is a pollen calendar?
Pollen calendars represent the time dynamics of airborne pollen present in a particular geographical area. They yield readily accessible visual details about various airborne pollen present throughout the year in a single picture.

Is this a new concept in India? Where else in the west has this calendar been used?

Though the concept is not essentially new, this is one of the major environmental concerns that had not been addressed for the Indian cities.

Such calendars are location-specific, as pollen concentrations are closely related to locally distributed flora. Europe, UK and the US are using regional pollen calendars in a big way to prevent and diagnose allergic rhinitis/hay fever and predict the timing and severity of the pollen season.

Why is it important to study pollen?
Pollen grains are male biological structures with the primary role of fertilisation, but when inhaled by humans, they may strain the respiratory system and cause allergies. Pollen found suspended in air can cause widespread upper respiratory tract and nasobronchial allergy with manifestations like asthma, seasonal rhinitis, and bronchial irritation.

About 20-30 per cent of the population suffers from allergic rhinitis/hay fever in India, and approximately 15 per cent develop asthma. Pollen is considered a major outdoor airborne allergen responsible for allergic rhinitis, asthma, and atopic dermatitis in humans. Considering these concerns, we conducted this study for Chandigarh.

What were the key findings?

The study highlights the variability of crucial pollen types in different seasons. Spring and autumn are two seasons when airborne pollen dominate. The findings will enhance the understanding of pollen seasons, which will in turn help minimise pollen allergies.

How will a pollen calendar benefit people, especially those who have respiratory issues?

A pollen calendar provides a clear understanding for clinicians, as well as people with allergies to identify the potential allergy triggers and help to limit their exposure during high pollen load season.

The early advisories can be prepared and disseminated through media channels to the citizens so that they can use protective gear during the period when the concentration of allergic pollen will be high. People can access the Pollen Calendar through the Care 4 Clean Air website.

Does the study infer that gardens and parks in the city contribute to the pollen and thus there must be proper scientific tree plantation?

It is important to involve experts while designing parks. We should try to plant trees/shrubs that release no or little pollen. Trees such as palms, nettle, safeda, white mulberry (shahtoot), congress grass, pine, have a high incidence of pollen.

What kind of trees must be grown alongside our roads or in parks?
Plant monoecious plants (male and female flowers on the same plant). Hibiscus, lilies, and holly that are grown widely in Chandigarh are examples of such plants. Cucumbers and squashes are also monoecious. Select plants with low to moderate pollen production.

Non-allergic or entomophilous plant species should be chosen to provide an allergen-free atmosphere. Examples of such plants include rose, jasmine, salvia, Bougainvillea, Raat ki rani and sunflower.