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Introduction Respirable crystalline silica (RCS) exposures in tanzanite gem mining have been linked to tuberculosis and silicosis among miners. We conducted a plot study to assess RCS exposures and to introduce safer mining practices in one small-scale underground tanzanite mine. Materials and methods Personal and area air samples for RCS were collected during tanzanite mining operations before and after improved work practices employed to reduce exposures and analyzed using X-ray diffraction. Area samples were collected at the rest area, located approximately 300 m underground and 100 m from other work activities. Improved practices included the use of wet drilling methods and drilling with new bits. Results A total of 33 personal and 4 area air samples were collected. Pre-intervention, mean exposures for all operations, drilling operations, non-drilling activities, and area samples were 122 mg/m3, 247 mg/m3, 34.3 mg/m3, and 1.95 mg/m3, respectively which exceeded the U.S. OSHA Permissible Exposure Limit (PEL) by 2,440 times for all operations, by 4,946 times for drilling operations, by 686 times for non-drilling activities and 39 times for area samples collected at an underground rest area. The post-intervention results showed a 99% reduction of RCS exposures for wet drilling operations, 98.5% reduction for non-drilling activities, and 36% reduction for area samples. Despite improvements, post-intervention RCS exposures during drilling had a mean of 2.08 mg/m3 or more than 41 times the OSHA PEL. Conclusions We successfully piloted a program to work with small-scale tanzanite miners to reduce RCS exposures and raise awareness about the occupational health risks of RCS, though additional measures are recommended to further reduce RCS exposures. Similar programs should be taken to scale throughout underground mining sites in Tanzania and other countries. [ABSTRACT FROM AUTHOR]

Quantification and characterization of waste are a pre-requisite for any planning and design for solid waste management. This paper reports on lessons from a research and pilot scale demonstration project on community level solid waste management in Dar es Salaam City, Tanzania. As part of the project, a study area was selected, and waste collection routes and service schedules were designed using the Heuristic-Deterministic approach. Households in the study area were given storage bags of different colours to facilitate on-site sorting and storage of the waste. The collected waste was transported and re-sorted so as to quantify it and determine its composition. The per capita waste generation rate (WG) was found to be between 300 and 450g per day and organic waste made up more than 78% of the total amount of waste. The moisture content of the waste was found to be 65% - 75% while the bulk density was 310 kgm.³. The study demonstrated among other things, that composting of solid waste could greatly alleviate solid waste management problems in Dar es Salaam City. It also showed that it was possible to manage waste at community level on cost- recovery basis. A further observation was that, the project improved greatly the environmental sanitation of the study area. [ABSTRACT FROM AUTHOR]