The Air Looks Clean, But Is It? What PM1 Pollution Means for Cities Like Kano

Last year, I visited a friend in Kano, one of Nigeria’s fastest-growing cities. The air felt dry and dusty, but not particularly smoky or smoggy. I assumed, like many people do, that if I couldn’t see or smell pollution, the air couldn’t be that bad.

But I was wrong.

A groundbreaking 2025 study from The Lancet Planetary Health has made me—and many scientists—rethink what we know about air pollution. The study, by Chi Li and a global team of researchers, focused on PM1 pollution: ultrafine particles that are smaller than 1 micron in diameter.

Unlike the more commonly monitored PM2.5, PM1 is small enough to penetrate not just your lungs, but your bloodstream and even your brain. This stuff isn’t just a lung problem—it’s a whole-body problem. And for cities like Kano, it may be the most overlooked environmental health threat we face today.

PM1: The Invisible Danger

To put this into perspective:

• A human hair is about 70 microns wide.
• PM2.5 (which most air monitors track) is 2.5 microns or smaller.
• PM1 is less than 1 micron—so tiny, it can slip past your body’s natural defenses and wreak havoc on your heart, brain, and immune system.

In the U.S., the study found that over 90% of PM2.5 pollution is actually PM1. While they focused on data from the U.S., their methods have global implications—especially for fast-urbanizing regions like Kano.

📊 Estimated PM1 and PM2.5 Levels in a Kano-like Urban Area (2015–2024)

The red dashed line represents PM1 (ultrafine particles).

The orange line shows PM2.5 (standard air quality measure).

The grey shaded area highlights that about 90% of PM2.5 in this scenario is actually PM1.

Why Kano Matters

Kano is home to over 4 million people and growing. It’s a city of vibrant markets, busy roads, and rapid development. But this also means:

1. Heavy use of diesel generators (especially during power outages)
2. Open burning of waste, especially plastic and electronics
3. Unpaved roads and construction dust
4. Biomass cooking in many households

These are all sources of fine—and ultra-fine—particles.

While Nigeria doesn’t currently monitor PM1 (and barely tracks PM2.5 in many areas), if we apply the logic of the Li et al. study, it’s safe to assume that a large proportion of air pollution in Kano is made up of PM1 particles.

Personal Experience: Dust, Diesel, and the Morning Commute

On my second morning in Kano, I joined a neighbor on a keke (tricycle) ride through the Sabon Gari market. Traffic was heavy, and the air was full of what looked like harmless dust. 

Later that evening, a quick check with a low-cost air quality sensor I brought along showed PM2.5 levels over 120 µg/m³—well above WHO’s safety limit of 15 µg/m³. And if 90% of that is PM1? That means we were breathing in nearly 100 µg/m³ of ultrafine particles.

DIY: How You Can Track Air Pollution 

Air monitoring doesn't have to be expensive or complicated. Here’s how you can monitor your own air and raise awareness in your community:

📡 Step 1: Get a Low-Cost Air Sensor

• Devices like PurpleAir, AirVisual Node, or IQAir AirVisual Pro are portable and easy to set up.
• They measure PM1, PM2.5, and PM10 in real-time.
• Cost: Around ₦200,000 ($150–200), but it can be shared between schools, neighbors, or NGOs.

📊 Step 2: Track Daily Trends

Monitor PM spikes during:

• Early morning cooking
• Traffic rush hours
• Open burning periods
• Share your results on WhatsApp or local community boards.

🧠 Step 3: Educate and Engage

Organize small community talks or school visits to explain the difference between visible dust and invisible PM1.

Advocate for cleaner cooking stoves and better waste management as a public health issue.

You can check out my previous post on Air quality Modelling

What Can Kano Do About PM1?

While regulating invisible particles seems tough, here are five practical steps that can reduce PM1 in urban Nigeria:

1. Clean Up Generator Use

Encourage use of inverter systems or solar panels.

Promote cleaner fuels like low-sulfur diesel.

2. Ban Open Waste Burning

Provide affordable waste collection.

Create community awareness campaigns about the hidden dangers of burning plastic.

3. Green Urban Spaces

Trees and vegetation help trap airborne particles.

Community gardens can be both air filters and food sources.

4. Public Transport Overhaul

Invest in low-emission buses and rail systems.

Regulate tricycles and older vehicles with emission checks.

5. Advocate for Air Quality Standards

Nigeria’s National Environmental (Air Quality Control) Regulations need to include PM1.

Pressure local government to install permanent air quality monitoring stations.

Final Thoughts: Don’t Let Clean-Looking Air Fool You

Just because you can’t see it, doesn’t mean it’s safe. PM1 is odorless, colorless, and often ignored—but its impact on your lungs, heart, and brain is very real.

The research by Chi Li and colleagues has started a vital conversation globally. Now it’s our turn to localize it. Whether you're in Kano, Lagos, or anywhere else in Nigeria, understanding PM1 is the first step toward breathing better and living longer.

Have you noticed any changes in how you feel during dusty harmattan months or traffic jams? Have you ever tried tracking your local air quality? Let us know in the comments—and share this article to start a conversation that really matters. 💨🇳🇬

Sources:

Chi Li, Randall V. Martin, Aaron van Donkelaar, et al. (2025). Estimates of submicron particulate matter (PM1) concentrations for 1998–2022 across the contiguous USA. The Lancet Planetary Health, 9(6): e491. DOI: 10.1016/S2542-5196(25)00094-4