Research Fellow in data science and air quality management at the Stockholm Environment Institute (SEI), Ngongang Wandji/ HANDOUTThe Nairobi City Marathon is scheduled for June 7, starting at City Hall Way and finishing at Uhuru Park, with a significant portion of the race unfolding on the Nairobi Expressway.
According to Ngongang Wandji, a Research Fellow in data science and air quality management at the Stockholm Environment Institute (SEI), the four monitoring devices have been positioned at key points along the course to provide continuous reading on air quality before, during and after the race.
Wandji revealed that SEI, working in partnership with Moja Expressway, selected the sites based on their strategic importance in understanding Nairobi's pollution patterns and urban environment.
"Moja Expressway came in very strongly to reaffirm their collaboration with Stockholm Environment Institute in using their infrastructure to map out four strategic sites along the route of the current Nairobi Marathon," he said. One of the sensors has been installed at JKIA, chosen for its proximity to industrial activity.
"We have one sensor at JKIA, which is a strategic site close to industries," Wandji explained. "Industries operate 24 hours, but there are specific periods when production is lower, and pollution is at its minimum."
"To ensure we get accurate data on pollution levels from industrial areas, we chose JKIA because of its proximity."
Another sensor sits at Uhuru Park, the emotional and logistical centrepiece of the marathon. "We chose Uhuru Park because that is where the heart of the marathon will be," Wandji noted.
The third device has been positioned at ABC Place in Westlands, the furthest point along the marathon distance. "We also have a device at the furthest point of the marathon distance at ABC Place in Westlands."
Wandji said the location was selected because it provides insight into pollution levels within a predominantly commercial area. "ABC is an area close to many offices. We do not expect any major concern there because many offices are closed on Sunday," he added.
The fourth and final sensor has been placed along Museum Road, a critical access point for the race. "We also have a device at the museum, which is the entry and exit point for the races."
He noted that Museum Road offers a unique mix of residential neighbourhoods, universities, and varying land-use activities, making it a vital site for gathering comprehensive environmental data. "That spot is also an intersection of residential areas for universities and different land uses. We wanted to ensure we had proper data representing those environments."
With the marathon taking place on a Sunday and road closures beginning at midnight, Wandji believes pollution levels are likely to remain relatively low. "Being on a Sunday means there will not be a lot of activity, plus traffic will be closed at midnight, so we are confident there will not be a lot of pollution in that area."
He added that the Expressway was chosen not only for its strategic positioning across Nairobi's urban hotspots, but also to guarantee the safety of the monitoring equipment.
"The reason we chose the Expressway is that we can ensure the safety of the gadgets and, more importantly, demonstrate that these locations are very strategic areas within the city's hotspots for understanding Nairobi's climatology."
Wandji said the monitoring devices will remain operational beyond this year's race, allowing researchers to build long-term air quality trends around the Nairobi City Marathon. "The devices remain operational before the marathon, during and even after, so that next year we can understand air quality trends for the Nairobi Marathon."
He further revealed plans to install five air-quality sensors for the 2027 edition of the City marathon. The sensors aim at providing Athletics Kenya with timely data on particulate matter 2.5 (PM2.5), a key measure of air pollution relevant to athlete health and environmental reporting. Roughly 30 times thinner than a human hair, PM2.5 particles can penetrate deep into the lungs, making accurate monitoring critical to strengthen the marathon's global standards and sustainability credentials.
