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Motor vehicle traffic is an important source of particulate pollution in cities of the developing world, where rapid growth, coupled with a lack of effective transport and land use planning, may result in harmful levels of fine particles (PM2.5) in the air. However, a lack of air monitoring data hinders health impact assessments and the development of transportation and land use policies that could reduce health burdens due to outdoor air pollution. To address this important need, a study of traffic-related PM2.5 was carried out in the city of Nairobi, Kenya, a model city for sub-Saharan Africa, in July 2009. Sampling was carried out using portable filter-based air samplers carried in backpacks by technicians on weekdays over two weeks at several sites in and around Nairobi ranging from high-traffic roadways to rural background. Mean daytime concentrations of PM2.5 ranged from 10.7 at the rural background site to 98.1 μg/m3 on a sidewalk in the central business district. Horizontal dispersion measurements demonstrated a decrease in PM2.5 concentration from 128.7 to 18.7 μg/m3 over 100 meters downwind of a major intersection in Nairobi. A vertical dispersion experiment revealed a decrease from 119.5 μg/m3 at street level to 42.8 μg/m3 on a third-floor rooftop in the central business district. Though not directly comparable to air quality guidelines, which are based on 24-hour or annual averages, the urban concentrations we observed raise concern with regard to public health and related policy. Taken together with survey data on commuting patterns within Nairobi, these results suggest that many Nairobi residents are exposed on a regular basis to elevated concentrations of fine particle air pollution, with potentially serious long-term implications for health.

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Tuhkanen, T. (2016). A multiresidue analytical method for trace level determination of antibiotics and antiretroviral drugs in wastewater and surface water using SPE-LC-MS/MS and matrix-matched standards. Analytical Methods, 8 (37), 6720-6729. doi:10.1039 AbstractAn analytical method for simultaneous determination of seven commonly used antibiotics and three antiretrovirals in surface water and urban wastewater at ng/L level has been developed. The method involves concentration and clean-up by solid phase extraction (SPE) followed by identification and quantification by liquid chromatography tandem mass spectrometry (LC-ESI-MS/MS). The use of matrix-matched calibration curves constructed by spiking surface water was evaluated for quantification and compared with the internal standard method using isotopically labelled compounds. The method gave absolute recoveries of 41-116% with most of the compounds having recoveries >50%. The LOQ ranged from 5-63 ng/L allowing for determination of the analytes at trace levels in the environmental samples considered. The difference in the quantification results obtained using surface water matrix-matched standards and internal standards were within ±20% margin.The method provides an affordable and relatively fast alternative with acceptable accuracy and precision. The method was applied to study the occurrence of the target analytes in surface water of Lake Päijänne and wastewater from Jyväskylä wastewater treatment plant (WWTP) in Central Finland. All target compounds were detected in the WWTP streams with concentration ranging between 10-570 ng/L while low ng/L levels were measured for some of the analytes in surface waters. The results institutes the need for further monitoring in in other WWTP streams and receiving waters as well as improvements of the wastewater treatment process with the aim of minimizing the pharmaceutical load in the effluents.

Presence of antimicrobial cocktails in the hydrological cycles is of interest because of their potential to mediate antimicrobial resistance within the natural environment. In this study, we determined the concentrations of selected antibiotics and antiretroviral drugs (ARVDs) in wastewater treatment plant (WWTP) effluent, effluent suspended particulate matter (SPM), surface waters and river sediments in Kenya in order to determine the extent of pollution within the sampled environment. Target analysis for the most common antibiotics and ARVDs was done. Sulfamethoxazole (SMX), ciprofloxacin (CIP), trimethoprim (TMP), norfloxacin (NOR), zidovidine (ZDV), lamivudine (3TC) and nevirapine (NVP) were analyzed using LC-ESI-MS/MS. Effluent aqueous phase had concentrations ranging between 1.2 µg L−1 to 956.4 µg L−1 while the effluent SPM showed higher concentrations, ranging between 2.19 mg Kg−1 and 82.26 mg Kg−1. This study shows emission of active pharmaceutical ingredients (APIs) from WWTP to the environment mainly occurs via the SPM phase, which is usually overlooked in environmental analyses. Concentrations in surface waters and river sediments ranged between 1.1 µg L−1 to 228 µg L−1 and 11 µg Kg−1 to 4125 µg Kg−1 respectively. ARVDs occurred at consistently higher concentrations than antibiotics in both the aqueous and solid samples. The wastewater treatment plants and lagoons where sludge degradation should occur, are sources of active pharmaceutical ingredients (APIs) including transformational products, nutrients and organic matter that are released back to the aqueous phase.

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