Air Quality Measurements in Uganda
Department of Physics & Astronomy, Colgate University
Airborne particulates are a major component of air pollution. Ambient (outdoor) particulates are estimated to cause 3 million premature deaths annually worldwide, with an additional 4.3 million deaths due to the indoor environment. Particles with aerodynamic diameters under 10 microns (PM10) can reach the lungs, and those under 2.5 microns (PM2.5) can reach the bloodstream. Exposure to airborne particulates is linked to a wide range of cardiovascular problems. In developed nations, particulate levels are routinely monitored, and when they exceed threshold levels, warnings are issued and activity restrictions are implemented to reduce them. However, in most developing countries, there is no government monitoring, and a lack of data will hamper future efforts to study the effects and mitigate the most important sources.
Long-term particulate matter (PM10) measurements were conducted during the period January 2016 to September 2017 at three sites in Uganda (Mbarara, Kyebando, and Rubindi) representing a wide range of urbanization, and during both wet and dry seasons. Particulate matter (PM10) samples were collected for 24-h periods on PTFE filters using a calibrated pump and analyzed gravimetrically to determine the average density. Particulate levels were monitored simultaneously using a light scattering instrument to acquire real time data from which diurnal variations were assessed. The PM10 levels averaged over the sampling period at Mbarara, Kyebando, and Rubindi were 5.8, 8.4, and 6.5 times higher than the WHO annual air quality guideline of 20 μg·m−3, and values exceeded the 24-h mean PM10 guideline of 50 μg·m−3 on 83, 100, and 86% of the sampling days. Higher concentrations were observed during dry seasons at all sites. Seasonal differences were statistically significant at Rubindi and Kyebando. Bimodal peaks were observed in the particulate levels as a function of time of day with higher morning peaks at Mbarara and Kyebando, which points to the impact of traffic sources, while the higher evening peak at Rubindi points to the influence of dust suspension, roadside cooking and open-air waste burning. Long-term measurement showed unhealthy ambient air in all three locations tested in Uganda.
One day of breathing: the left air filter has collected 24 hours of particulates through a pump pulling air at about the same rate as human lungs. On the right, a new air filter for comparison.