Greening Our Cities: A Research-Based Path to Cleaner Air in Bangladesh

How strategic green infrastructure can combat urban air pollution based on my recent research findings

If you live in a city like Dhaka, Khulna, or Mymensingh, you don't need a scientist to tell you the air is thick. You feel it in your lungs, see it haze the skyline, and know it's a daily reality. As a researcher deeply invested in our urban environments, I've moved beyond just observing the problem. My recent work, culminating in a semi-systematic review published in Water, Air, & Soil Pollution (2025), focuses on a powerful, natural solution: Green Infrastructure (GI).

This research synthesizes global evidence to answer a critical question: How can we strategically use nature—like parks, street trees, and green roofs—to fight urban air pollution, and what does this mean for Bangladesh?

Image by DC Studio on Freepik

Green Infrastructure for Sustainable Cities: A Smarter Path to Urban Resilience

The Scale of the Problem: More Than Just Dust

Urban air pollution is a complex cocktail of harmful particles and gases. Our review highlighted that the most pervasive and health-damaging pollutants are:

• Particulate Matter (PM2.5 and PM10): These tiny particles, largely from vehicle exhaust, industrial emissions, and construction, can penetrate deep into our lungs and bloodstream, causing respiratory and cardiovascular diseases.
• Nitrogen Dioxide (NO2): A gas primarily from combustion engines, it's a key component of smog and a serious respiratory irritant.

In many rapidly urbanizing areas of Bangladesh, the levels of these pollutants consistently exceed national and international safety standards, creating a silent public health crisis.

The Promise of Green Infrastructure: It's Not Just About Beauty

Green Infrastructure isn't just about planting a few trees for shade. It's a strategic network of natural and semi-natural systems designed to deliver specific ecosystem services. Our research confirms that GI can be a potent weapon against air pollution through two main mechanisms:

1. Deposition

Leaves and branches act as physical filters, trapping and absorbing particulate matter.

2. Dispersion

By influencing wind patterns, well-placed vegetation can help break up and disperse pockets of polluted air.

However—and this is a crucial finding—GI is not a one-size-fits-all solution. Its effectiveness is highly dependent on scale, urban design, and the type of vegetation.

Key Findings from My Research: What Really Works?

After analyzing dozens of studies from around the world, several critical insights emerged that are directly relevant to Bangladeshi cities:

Trees are Champions, But Placement is Key

Tree-dominated GI (like roadside canopies and urban parks) consistently outperforms lawns or hedges in reducing pollutants. However, in extremely compact "urban canyons" with narrow streets and high-rises—a common feature in old Dhaka—poorly planned trees can actually trap pollution by restricting airflow. The solution is strategic planting that encourages, not blocks, air circulation.

Scale Matters Dramatically

Our research revealed that the impact of green infrastructure changes significantly depending on the scale:

• At the street level, the total amount of greenery has a minimal direct impact on pollution.
• At the city and community level, tree cover becomes the dominant factor, significantly reducing pollution through regional dispersion and deposition.

This tells us that isolated patches of green won't cut it; we need connected, city-wide networks.

The Urban Form Dictates Success

Cities with more open layouts and polycentric designs allow for better air circulation. Our research found that compact urban forms combined with integrated green spaces are associated with better air quality, as they can reduce reliance on cars and create pollution-buffering green zones.

Seasonal Variations Play a Role

The effectiveness of GI changes with the seasons. Leaf density, humidity, and rainfall all influence how much pollution vegetation can capture. Long-term, climate-sensitive planning is essential.

Connecting Research to Reality: My On-the-Ground Work

This global review isn't just theoretical for me. It directly informs my local monitoring and projects in Bangladesh. The findings have helped shape my approach to analyzing urban air quality patterns and advocating for evidence-based green infrastructure planning in our cities.

A Clear Path Forward for Urban Bangladesh

The evidence is clear: weaving Green Infrastructure into the fabric of our cities is not a luxury—it's a necessity for public health and sustainable development. Based on my research, here is what we must advocate for:

• Prioritize Native Trees: Focus on planting dense, native tree species along major roads and in parks to act as natural air filters.
• Think in Networks, Not Patches: Plan interconnected green corridors that facilitate air movement and pollutant dispersion across the city.
• Retrofit the Concrete Jungle: Promote green roofs and vertical gardens on existing buildings to increase greenery without needing more land.
• Mandate Green Planning: Urban policy must integrate GI as a core component of all new development projects.

The challenge of urban air quality is daunting, but it is not insurmountable. By combining global research with local action and data, we can chart a course toward cleaner, greener, and healthier cities for all Bangladeshis.

Research Reference: This blog post is based on my research published in:
Idris, A. B., Hossain, M. M., Islam, M. A., Hossain, M. Z., & Islam, M. T. (2025). Green Infrastructure and Urban Air Quality: A Semi-Systematic Review of Multiscale Evidence, Methodologies, and Policy-Relevant Insights. Water, Air, & Soil Pollution, 236, 993.