Credit: Science Pulse (Facebook)
Lichens are indeed recognized globally as bioindicators of air quality, particularly due to their high sensitivity to airborne pollutants like sulfur dioxide (SO₂), nitrogen oxides (NOx), ozone, and heavy metals.
They absorb water and nutrients directly from the atmosphere through their surface, making them vulnerable to contaminants in the air.
There are three main types of lichens:
- Crustose (flat, crusty)
- Foliose (leafy)
- Fruticose (bushy)
Research shows that in urban or industrial areas with high pollution, lichen diversity drastically declines or certain species disappear altogether.
On the other hand, in clean, unpolluted environments, a variety of lichen species can thrive and even colonize large surfaces of trees, rocks, and soil.
Scientists and environmental monitoring agencies use lichen surveys to evaluate air quality over time.
Some lichens are even used to map pollution gradients across cities and forests. For instance:
In Europe, monitoring lichens has helped track forest decline due to acid rain.
In India, studies have used lichen biodiversity to assess urban air pollution in cities like Delhi, Mumbai, and Kolkata.
Their disappearance is not just a visual clue — it's backed by measurable physiological stress, DNA damage, and metabolic disruption in the lichens themselves, all due to air contaminants.
So yes — the presence of healthy lichens is a strong biological assurance of clean air.
