The Punjab government has announced plans to expand its “Liquid Tree” project as part of efforts to tackle urban air pollution through scientific and nature-based technologies.

Pakistan’s first Environmental Protection Agency-certified liquid tree is expected to be moved from Faisalabad to Lahore under the expansion plan. The initiative uses microalgae inside specially designed photobioreactors to absorb carbon dioxide and release oxygen through photosynthesis.

What Is a Liquid Tree?

A liquid tree is a compact, water-filled structure containing microalgae.

Like conventional trees, the algae absorb carbon dioxide during photosynthesis and release oxygen. The systems can be installed in places where there is insufficient space or suitable soil for planting mature trees, including congested commercial districts, transport stops and paved urban centres.

Liquid trees are sometimes incorporated into benches, bus shelters and other forms of street furniture. Their small footprint makes them suitable for densely developed areas, although they are not a substitute for natural forests or urban tree cover.

More Than 100 Microalgae Types Collected

Punjab officials said more than 100 types of microalgae had been collected from regions extending from Karachi to Khyber for research connected to the project.

Different algae species can vary in their ability to survive local temperatures, absorb pollutants and function efficiently under changing environmental conditions.

Testing locally collected species could help authorities identify varieties better suited to Punjab’s heat, sunlight and air-quality conditions.

Wider Pollution-Control Measures Announced

The liquid-tree expansion forms part of a broader environmental programme announced by the provincial government.

The measures include:

  • Green buffer zones around industrial areas
  • Mandatory plantation initiatives
  • Stronger controls on tree cutting
  • Scientific monitoring of urban pollution
  • Expansion of environmentally focused infrastructure

Green buffers can help separate industrial sites from nearby communities while vegetation captures some dust and airborne particles. Their effectiveness, however, depends on appropriate plant selection, adequate width and long-term maintenance.

Technology Cannot Replace Natural Trees

Although liquid trees can provide environmental benefits in heavily paved areas, they cannot deliver all the services offered by natural vegetation.

Living trees cool streets through shade and evaporation, absorb rainwater, reduce noise, support wildlife and improve soil health. Urban forests also help reduce the heat-island effect created by roads, concrete and buildings.

Liquid trees can complement urban forests, but they cannot replace the ecological value of living trees and healthy green spaces.

The strongest urban air-quality strategy would combine microalgae systems with emissions controls, cleaner transport, industrial regulation and widespread protection of natural tree cover.

Performance Must Be Measured Publicly

The project’s long-term value will depend on transparent monitoring.

Authorities should regularly assess:

  • Carbon dioxide absorption
  • Effects on nearby air quality
  • Energy and water requirements
  • Maintenance costs
  • Algae health and replacement needs
  • Performance during extreme heat and smog
  • Environmental benefits compared with conventional planting

Publishing this data would allow researchers and the public to evaluate whether liquid trees are producing meaningful improvements or primarily serving as experimental installations.

Punjab’s initiative demonstrates how biological technology may support cleaner cities. Its success will ultimately depend on whether it forms part of a larger, evidence-led programme to reduce pollution at its source.