Abstract
Abstract. Air pollution is understudied in sub-Saharan Africa, resulting in a gap in the scientific understanding of emissions, atmospheric processes, and impacts of air pollutants in this region. The Rwanda Climate Observatory, a joint partnership between MIT and the government of Rwanda, has been measuring ambient concentrations of key long-lived greenhouse gases and the short-lived climate-forcing pollutants CO2, CO, CH4, black carbon (BC), and O3 with state-of-the-art instruments on the summit of Mt. Mugogo (1.586∘ S, 29.566∘ E; 2590 m above sea level) since May 2015. Rwanda is a small, mountainous, and densely populated country in equatorial East Africa, currently undergoing rapid development but still at less than 20 % urbanization. Black carbon concentrations during Rwanda's two dry seasons (December–January–February, DJF, and June–July–August, JJA), which coincide with the two regional biomass burning seasons, are higher at Mt. Mugogo than in major European cities with daily values (24 h) during the dry season of around 5 µg m−3 (daily average concentrations ranging from less than 0.1 to over 17 µg m−3 for the entire measurement period). BC baseline concentrations during biomass burning seasons are loosely correlated with fire radiative power data for the region acquired with a MODIS satellite instrument. The position and meteorology of Rwanda is such that the emissions transported from both the northern and southern African biomass burning seasons affect BC, CO, and O3 concentrations in Rwanda. Spectral aerosol absorption measured with a dual-spot Aethalometer varies seasonally due to changes in types of fuel burned and the direction of pollution transport to the site. Ozone concentrations peaked during Rwanda's dry seasons (daily measured maximum of 70 ppbv). The understanding and quantification of the percent contributions of regional and local (beyond large-scale biomass) emissions is essential to guide policy in the region. During the rainy seasons, local emitting activities (e.g., cooking, transportation, trash burning) remain steady, regional biomass burning is low, and transport distances are shorter as rainout of pollution occurs regularly. Thus, local pollution at Mugogo can be estimated during this time period and was found to account for up to 35 % of annual average BC measured. Our measurements indicate that air pollution is a current and growing problem in equatorial East Africa.
Highlights
According to recent data collected and published by the World Bank, particulate air pollution in most African countries is above the annual average guideline values recommended by the World Health Organization (WHO)
Rwanda has two rainy seasons roughly occurring in March–April–May (MAM) and September–October– November (SON) and two dry seasons during DJF and JJA
1. during Rwanda’s two dry seasons, transported pollution led to high black carbon and carbon monoxide levels at the Rwanda Climate Observatory (RCO), surpassing concentrations measured in many major cities elsewhere
Summary
According to recent data collected and published by the World Bank, particulate air pollution in most African countries is above the annual average guideline values recommended by the World Health Organization (WHO). Little scientific research has been published on air quality in Africa, which can be approximated by the number of paper results from the search terms “air pollution + country name”. World Bank collected data and model approximations estimate higher PM2.5 exposure in African versus European countries (Fig. 1). The WHO reported in 2013 that one in eight premature deaths globally can currently be linked to poor air quality (WHO, 2013), while another, more recent re-. DeWitt et al.: Air Quality in Rwanda port showed that these deaths are concentrated in developing countries (World Health Organization, 2016). Widespread crop fires in northern and southern Africa, prevalent in boreal winter (December–January–February, DJF) and austral winter and part of austral spring (June–July–August, JJA, and September–October), respectively, are known to increase aerosol and ozone concentrations in this region and transported molecular and aerosol fire tracers associated with elevated ozone have been measured as far as the Pacific and Indian oceans (Field et al, 2016; Real et al, 2010)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
