Spatial ambient air quality analysis and its impact on traffic police within the central business district (CBD) in Nairobi Kenya

Introduction
In Kenya, every person is entitled to a clean and healthy environment. Although clean air is a basic requirement for human health and well-being, air pollution continues to pose a significant threat to health worldwide. In Kenya the traffic police officers (TPO’s) spend most of their time on the road controlling traffic a condition that exposes them to automobile pollution.

Methods
Emissions of CO, CO2 and NOx from vehicles in the CBD in Nairobi were sampled. A total of 117 TPO’s participated in the study. A gas Aspiration pump AP-20 together with detector tubes were used to determine the levels of NOx, CO emissions while Testo 435 multifunction measuring instrument was used to determine CO2 levels, wind velocity and temperature at ten purposely selected sites within the CBD.

Results
CO2, CO and NOx sampled had means of 634.80 ppm, 12.74 ppm 2.56 ppm respectively. A statically significant difference between the sample means and the population means was observed suggesting that the traffic police officers were exposed to CO, CO2 and NOx levels that were above the OEL-RL for the gases. 88% of the TPO’s reported to have been affected, 2% were not affected by the pollutants in their work environment while 10% reported a neutral position.

Discussion
The high pollution levels observed above could be attributed to the use of second hand vehicles. Lack of regular maintenance and tune up of the vehicles especially by public transport vehicles owners, traffic congestion, lower wind speed within the CBD and lack of fitting catalyticconverters on the vehicles were other probable factors.

The TPO’s who were exposed to these pollutants were at high risk of being affected by the pollutants. Similarly members of the public who are normally in the CBD were equally exposed and therefore were expected to have been affected by the pollutants.