Chief Steward - Green Africa Foundation
Released for Global attention on May 16, 2025, at 1600 hrs, Nairobi, Kenya

1. Introduction: A Personal Wake-Up Call

Our team at the Green Africa Foundation recently began using a precision air quality monitor called the Aranet4 to track carbon dioxide (CO₂) levels, temperature, and humidity in real time across various regions of Kenya. What we discovered was alarming: Many enclosed environments-homes, offices, and especially cars - often record dangerously high CO₂ levels, even when the air conditioning is on. This silent threat is hidden in plain sight, and it's time we bring it to light.

2. The Science of Stagnant Air: Why CO₂ Accumulates

• CO₂ is a natural by-product of human respiration.
• In enclosed spaces without fresh airflow, levels can rise rapidly.
• CO₂ concentrations between 1000 and 2000 ppm impair cognitive functioning; above 2000 ppm, it causes drowsiness and headaches.
• When combined with low air pressure (e.g., 821 hPa at high altitudes like Nairobi), high humidity, and elevated temperatures, the body's stress levels increase while oxygen availability and ventilation efficiency decrease.

According to the U.S. Environmental Protection Agency (EPA) and ASHRAE, these conditions can reduce cognitive performance and increase fatigue, directly impacting task performance and health.

3. Field Observations: Real-World CO₂ Levels in Kenyan Vehicles

To verify these concerns, we conducted an observational study using the Aranet4 sensor across various regions of Kenya, including Nairobi, Malindi, Kitui, Eldoret, and Naivasha. In each area, we assessed CO₂ levels in indoor and in-vehicle settings across 3 to 8 vehicles per region under varying conditions.

• Malindi: Indoor CO₂ levels in our accommodation ranged from 400 to 480 ppm. However, inside vehicles with closed windows, CO₂ levels rapidly exceeded 2,000 ppm. Upon opening the windows, the levels halved within minutes.
• Nairobi: Indoor readings in our locations varied between 500 and 990 ppm, depending on the neighborhood. In-car CO₂ concentrations spiked to between 1,900 and 4,300 ppm, regardless of vehicle type or whether the AC was on. Opening the windows drastically improved air quality.
• Kitui, Eldoret, and Naivasha: Similar trends were observed; vehicles operating in recirculation mode experienced a rapid buildup of CO₂, which was only reversed with direct ventilation.

These measurements, validated by the high-accuracy Aranet4 device using NDIR (non-dispersive infrared) technology, provide tangible, real-world evidence that Kenyans are frequently breathing unsafe air within spaces intended for transportation or shelter.

4. Cars: The Deadliest Trap

Car cabins with AC in recirculation mode can reach dangerous CO₂ levels (2500-5000 ppm) in under 30 minutes. This is particularly hazardous for:

• Drivers, which can lead to impaired attention and delayed reaction times.
• Passengers, especially children and the elderly.

In some traffic accidents, fatigue or drowsiness may be mistakenly attributed to poor sleep-while CO₂ could be the unseen cause.

5. Linking to Road Safety

Kenya continues to face tragic road accidents despite significant efforts. Scientific evidence globally shows that CO₂ - induced fatigue can lead to fatal driver errors. In a tropical country like Kenya, CO₂, heat, and humidity combine to form a triple threat that:

• Worsens focus
• Triggers stress responses
• Increases the likelihood of human error

Policy Link: NTSA road safety campaigns must include air quality awareness.

6. What Must Be Done (Call to Action)

For the Public:

• Ventilate rooms and vehicles regularly.
• Avoid continuous use of air recirculation in cars.
• Install affordable CO₂ monitors in indoor spaces and vehicles.

For Policy Makers:

• Include CO₂ safety awareness in driver education and NTSA roadworthiness standards.
• Enforce mandatory ventilation standards in public transport vehicles, classrooms, and offices.
• Support incentives for local manufacturing or importing of affordable air quality sensors.
• Promote building codes that include controls for CO₂, temperature, and humidity.

For Researchers and Industry:

• Study real-world CO₂ exposure levels in matatus, offices, homes, and schools.
• Publish links between high indoor CO₂ levels and public health outcomes, including accident statistics.

7. A New Frontier of Climate and Health Leadership

This issue goes beyond comfort, life and death, productivity, and clarity of mind. As Kenya strives for climate resilience and sustainable development, indoor air quality must be recognized as a critical health and safety policy component. The enemy is invisible but deadly. Neglecting indoor air quality jeopardizes our health, safety, and future. Let us act now, not to breathe easier, but to live smarter, safer, and longer.

Of course, this was a limited study that might not paint an exact picture across the country, but the potential implications for road safety are severe. A detailed scientific exploration may offer intriguing insights. Recognizing and addressing this invisible yet preventable threat is crucial for our immediate well-being and future prosperity.

Think green, act green
Isaac Kalua Green, Ph.D., CBS, MBS, HSC
www.kaluagreen.com / green@greenafricagroup.africa