Personal and indoor exposure to PM_2.5 and polycyclic aromatic hydrocarbons in the southern highlands of Tanzania: A pilot-scale study

Personal and indoor exposure to PM_2.5 and polycyclic aromatic hydrocarbons (PAHs) were measured in households in the Njombe district of Tanzania. Cooking is conducted indoors in this region due to its high elevation, cool climate, and heavy seasonal rainfall. Kitchens are often poorly ventilated, resulting in high exposures to combustion-related pollutants. Sampling sites were selected to represent typical cooking practices across regional socio-economic divisions. These include the use of open wood fires, charcoal, a mix of charcoal and kerosene, and liquid petroleum gas (LPG) for cooking fuels. PM_2.5 average personal exposure was 14 μg/m ³ (±3, n = 3) for LPG, 88 μg/m³ (±42, n = 3) for kerosene/charcoal mix, 588 μg/m³ (±347, n= 3) for charcoal alone, and 1574 μg/m³ (±287, n = 3) for open wood fires. Total PAH average personal exposures were less than 1 ng/m³ (±1, n = 3) for LPG, 57 ng/m³ (±16, n = 3) for kerosene/charcoal mix, 334 ng/m³ (±57, n = 3) for charcoal alone, and 5040 ng/m³ (±909, n = 3) for open wood fires. Benzo[a]pyrene equivalent exposures for US EPA's priority PAH pollutants were 0 for LPG, 8 ng/m³ for kerosene/charcoal mix, 44 ng/m³ for charcoal, and 767 ng/m³ for open wood fire. Inhalable pollutants are present at unacceptably high levels, exceeding indoor air quality standards for all but LPG fuels. Relative results provide an exposure profile for rural East Africa and support the feasibility of conducting a larger scale smoke exposure campaign in the region. The use of "fuel efficient" wood stoves for the reduction of PM_2.5 and PAH exposure was measured in a local secondary school. Proper use of "fuel efficient" wood stoves reduced personal and indoor exposure to measured pollutants by more than 90%, supporting further investigation into the applicability of this technology to significantly improve indoor air quality.