Context
Recently, cities like Kolkata and other parts of India have reported a significant surge in pollen concentrations, leading to a spike in seasonal allergies, hay fever, and respiratory issues. This phenomenon is increasingly linked to changing climatic patterns and urban vegetation choices.
1. Understanding Pollen (Biological Basics)
- Definition: Pollen consists of microscopic grains discharged from the male part of a flower (anther) or from male cones. They are the male gametophytes of seed plants.
- Dispersal (Pollination):
- Anemophilous plants: These are wind-pollinated plants (e.g., grasses, oaks, pines). They produce vast quantities of lightweight pollen, which are the primary cause of allergies.
- Entomophilous plants: These are insect-pollinated plants. Their pollen is usually heavier and stickier, making them less likely to become airborne.
2. The Link with Climate Change
- Extended Growing Seasons: Rising global temperatures cause plants to bloom earlier and for longer durations, extending the “pollen season”.
- The CO2 Factor: Higher atmospheric Carbon Dioxide (CO2) levels act as a “fertilizer” for plants. Studies show that increased CO2 can lead to plants producing more potent and a higher volume of pollen grains.
- Urban Heat Island Effect: Cities stay warmer than rural areas, trapping pollen and pollutants near the ground, worsening the impact on urban populations.
3. Public Health: Pollen and Air Quality
- Aeroallergens: Pollen is classified as a biological air pollutant.
- Thunderstorm Asthma: A rare but serious phenomenon where a thunderstorm “shatters” pollen grains into much smaller particles. These tiny particles can bypass the nose and enter deep into the lungs, causing acute asthma attacks.
4. Policy and Urban Planning
- Botanical Sexism: A term often used to describe urban planning that prioritizes planting male trees (to avoid the “litter” of fruits and seeds). Since male trees produce pollen, this practice significantly increases the pollen load in urban air.
- Mitigation: Experts suggest a “biodiverse urban forest” approach, mixing male and female trees and prioritizing insect-pollinated species to reduce airborne allergens.
5. Scientific Advancement (Predictive Model)
A team of researchers from France and the United States has developed a new computational model to predict how pollen behaves in the air.
- The study was published in the journal Physics of Fluids.
- The model is called DF-PIBM (Direct-Forcing Porous Immersed Boundary Method).
This model helps scientists understand:
- How pollen grains move with wind
- When and how they are released from trees
- How far they can travel in the atmosphere
With reference to rising pollen levels and seasonal allergies, consider the following statements:
1. Wind-pollinated plants produce large quantities of lightweight pollen that are more likely to cause allergies.
2. Higher atmospheric carbon dioxide levels can increase the quantity of pollen produced by plants.
3. Thunderstorm asthma occurs when pollen grains are broken into finer particles that can penetrate deeper into the lungs.
Which of the statements given above are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Answer: D
Explanation:
Statement 1 is Correct: Wind-pollinated (anemophilous) plants release large amounts of light, airborne pollen, which easily spreads in the air and is the major cause of allergies.
Statement 2 is Correct: Increased atmospheric CO₂ acts as a fertilizer, leading to greater plant growth and higher pollen production.
Statement 3 isCorrect: In thunderstorm asthma, pollen grains absorb moisture and burst into very fine particles, which can bypass the nose and enter deep into the lungs, triggering severe asthma attacks.
