NAIROBI, Kenya – The sun beats down on Tom Mboya Street, where buses belch black smoke into the air and vendors shout amid the constant honking of matatus (minibus taxis). 

The air is already thick with smoke before midday. In the midst of this stands James Muro, a fruit seller whose workday is measured in dust, fumes and strained breaths.

In 2024, he began having a persistent cough. At first, he thought it was nothing serious. But as weeks went by, the symptoms worsened – chest tightness, shortness of breath and eventually a bloody cough. 

A visit to Kenyatta National Hospital revealed a lung infection aggravated by long-term exposure to polluted air. 

“It felt like the city I depend on for survival was slowly choking me,” he says. For him, the city’s fading green lungs aren’t an abstract concern, they are a daily struggle to stay healthy. Muro’s struggle reflects the growing health toll of Nairobi’s shrinking spaces and rising air pollution.

Romanus Opiyo, an environmentalist at Stockholm Environment Institute, says that urban areas block air circulation, leading to poor air quality and compromised health. 

“Lack of green spaces and built-up areas act as blockades to air circulation which actually compromises people’s health and wellbeing,” said Opiyo, who stresses the importance of addressing challenges like human capital, budget allocation and community awareness and proper implementation of the Nairobi integrated Urban Development master plan.

“If there is an adequate budget allocation, national staff who are aware and also in numbers to reinforce awareness to the community and proper implementation of plans we will be able to solve these  gaps.”

“The loss of green spaces is not just an environmental issue. It is an urban health crisis. Vegetation acts as a natural filter, absorbing harmful pollutants such as particulate matter (PM 2.5).” 

PM 2.5 is a component of air pollution that is less than 2.5 micrometers in diameter,  30 times thinner than a human hair. These microscopic particles easily bypass the body’s natural defenses, lodge deep within the lungs, and penetrate the bloodstream.

This pollutant is linked to cardiovascular diseases; chronic respiratory illnesses, particularly chronic obstructive pulmonary disease (COPD) and severe asthma and lung cancer. It also causes severe childhood conditions like pneumonia and stunted lung development.

Falling short of global standards

The Kenyan Constitution (2010, Article 42) guarantees every citizen the right to a clean and healthy environment. Yet, the disappearance of Nairobi’s green lungs shows how far reality falls short of this promise. 

WHO and UN-Habitat recommend that every resident should have access to at least 9–10 m² of green space per person, according to a 2016 WHO report on Urban Green Spaces and Health.

Nairobi, however, falls far below these thresholds.  According to the 2020 UN-Habitat Nairobi Public Space Inventory and Assessment Report, there are 826 public spaces in Nairobi City County. They occupy a combined area of 3106.4Ha – only 5.32% of the built up area – and translate to 6.56m2 per capita of public open space. 

Kenya’s Vision 2030 identifies environmental management as a pillar of sustainable development, while its National Land Use Policy calls for equitable access to urban green space. However, weak enforcement has seen Nairobi lose its green cover.

“One of the remaining indigenous urban forests in Kenya is Ngong Road Forest. However it faces repeated threats from rapid urbanization, expanding roads, encroachment for real estate and development, and installing utilities has continued to reduce the forest boundaries,” explains Wanjiru Hungi, a representative from Ngong Road Forest Association.

“Illegal logging and informal settlements have continually reduced the boundaries of the forest. Land grabbing and irregular allocations remain the most critical threat in the forest undermining the legal protection of the land,” she emphasises.

According to a study published in 2020 by Francis Oloo and colleagues, from approximately 6,600ha of forest land, 720 ha has been lost between 2000 and 2019, representing a loss of about 11%.  There is a clear need for Nairobi to work towards improving the amount of urban land designated, used and experienced as public space. This decline undermines Sustainable Development Goal (SDG) 11, which calls for inclusive, safe, resilient, and sustainable cities with equitable access to green spaces.

“Sometimes it feels like someone is pressing down on my chest, the pain comes suddenly and I just stop what I am doing until it passes,” says Muro. 

Steadily worsening air pollution

Air pollution is the leading risk factor for death in Nairobi. The health burden is already evident. According to the State of Global Air 2024, air pollution contributed to more than 30,000 deaths in Kenya in 2021, representing 8% of all deaths nationwide. Children, the elderly, outdoor workers such as street vendors and traffic police, and people with existing conditions like asthma or diabetes face the highest risks.

Chest tightness is a common sign of PM 2.5 damage, which inflames the lungs and reduces airflow that can strain the heart and chest muscles.  

“Once inhaled, PM 2.5 triggers inflammation and oxidative stress, weakening the lungs and making people more vulnerable to infections,” explains Dr Joseph Ndung’u,  a specialist at a local hospital. 

In Nairobi, exposure to PM 2.5 is rising at an alarming pace. The annual average PM 2.5 concentration in Nairobi, Kenya is 18.4 µg/m³ – significantly higher than the World Health Organization (WHO)’s recommended annual threshold of 5 µg/m³. 

A recent health impact assessment for Nairobi using WHO’s AirQ+ tool suggests that this level of pollution can cause 400 and 1,400 premature deaths annually in the city. 

The steady increase in air pollution over the last decade has been fueled by motor vehicle emissions, industrial activity, open burning of waste, and the continued loss of trees and green buffers that once absorbed some of these pollutants.

Trends in annual average PM 2.5 levels Kenya from 1990-2020: State of Global Air (2024)

Air Pollution and disease

Trends over the last decade show a troubling rise but, unlike infectious diseases, the effects of air pollution are hidden and cumulative, building often unnoticed over time until they manifest as chronic illness. 

The missing link

Non-motorised transport (NMT) is often described as the backbone of sustainable urban mobility. Unlike motorized transport, it produces zero emissions, improves physical health, and reduces congestion.  

In Nairobi, however, the connection between green spaces and NMT is steadily eroding. Parks, tree-lined corridors, and public walkways that once provided shaded, safe routes for pedestrians and cyclists have been lost to urban sprawl and poor planning. 

The result is twofold: more emissions from motor vehicles as residents rely heavily on matatus and private cars, and higher risks of traffic injuries as pedestrians are forced onto unsafe, congested roads.

“Shifting even a small percentage of short trips from cars to walking and cycling can improve air quality, while also reducing greenhouse gas emissions,” says Carly Gilbert-Patrick, the UN Environment Programme’s (UNEP) team leader for active mobility, digitalisation and mode integration. 

“It’s about reclaiming space and dignity for the people who rely on walking and cycling every day. From this we can see multiple benefits including environment, air quality, road safety, equity.”

The decline of green spaces has led to a decline of safe walking and cycling routes. This loss of active transport opportunities contributes to a sedentary lifestyle, which is driving up cases of obesity, diabetes, and cardiovascular disease, illnesses that could be prevented through daily walking or cycling. 

Road traffic injuries are the leading cause of death in 15 to 29-year-olds worldwide, with Kenya amongst the hardest hit in Africa, according to the WHO. Nairobi records thousands of pedestrian and cyclist injuries annually, many of them fatal.

Kenya has recognised this gap. In 2009, the Integrated National Transport Policy stressed low-emission mobility as a national priority, and the 2017 Non-Motorized Transport Policy calls for safer walking and cycling networks. 

Yet, on the ground, progress remains slow, and Nairobi continues to expand highways while neglecting pedestrian and cycling infrastructure. 

 “I work to feed myself, but the city’s streets are slowly stealing my strength.  The air I need to survive is slowly turning against me and  everyday is a battle between survival and sickness,” Muro says.

This article was produced as part of a collaboration between Health Policy Watch and KEMRI’s Health Journalism and Public Health course.

Image Credits: Timon Abuna, Google Earth.