Household fuel use and pulmonary tuberculosis in western Nepal: A case-control study

Abstract

BACKGROUND: Whether cooking with solid fuels, as occurs widely in developing countries, including Nepal, is a risk factor for pulmonary tuberculosis (PTB) is uncertain. Epidemiologic studies have produced variable results. This case-control study sought to resolve this issue with a large sample size and a population-based control group. METHODS: PTB cases (N = 581), aged 18 to 70 were recruited from diagnostic centers in Kaski and neighboring districts of Nepal. Population-based controls (N = 1,226) were recruited. Persons who had previously been diagnosed with TB were excluded. Questionnaires were administered at participants’ homes. RESULTS: Using liquefied petroleum gas (LPG) as the cookstove reference fuel, for women the odds ratio (OR) for having a primary cookstove that used wood was 0.21 (95% CI: 0.08,0.52); for men the corresponding OR was 0.80 (0.37, 1.74). For biogas, the OR for women was 0.24 (0.06,0.87) and for men, 1.41 (0.61, 3.23). CONCLUSIONS: The unexpected finding of a higher risk for women using LPG cookstoves, relative to wood or biogas-burning cookstoves, may be attributable to excluding persons with prior TB. A possible explanation is that emissions, such as ultrafine particles, formed during LPG combustion promote PTB manifestation in infected people who have not previously had PTB. The damage from the initial PTB leaves them susceptible to the PTB-promoting effects of smoke from wood fires. Further studies, excluding participants who have previously had TB are needed to confirm these findings. Use of exhaust hoods to the outdoors for all stoves, well-ventilated kitchens, and gas stoves raised above ground would reduce exposures.

Logistic regression analysis of environmental and other variables and incidences of tuberculosis in respiratory patients

“…In indoor air, exposures to fine particles are from the combustion of household fuels and poor ventilation in the kitchen 10 , 18 . Both kitchen ventilation and household combustions associate with TB, especially in women 14 , 15 , 18 , 53 . In this context, data were compiled under the category kitchen, which had three independent variables, namely, (i) kitchen location (KLO) (partitioned inside the house (PIH) or non-partitioned inside the house (NPIH)), (ii) cooking fuel uses (CFU) (LPG or solid fuels) and (iii) ventilation in the kitchen (VEN) (at least one window of size 2ft by 2ft or no window).…”

“…Several studies 15 – 21 have shown that exposure to fine particulate matter (PM 2.5 ; particles of size less than or equal to 2.5 microns) from burning biomass, smoking, kerosene fuel, vehicular pollution, etc. trigger the risk of TB infection and full-blown disease.…”

“…More than 65% of rural households in the states of Uttar Pradesh and Bihar are dependent on kerosene lamps as their primary source of lighting 32 . The household air pollution is increasing due to uses of solid fuels and kerosene, making a large population vulnerable to TB infection 8 , 11 , 13 , 15 , 33 , 34 .…”

“…Most of the studies noted above 8 , 11 , 13 , 15 , 28 , 33 – 41 , use only a subset of variables and lack comprehensive analysis. These studies rely on the unadjusted odds ratio (UOR).…”

Biomass Fuel Use and Cardiac Function in Nepali Women

“…The initial basis for the selection of study participants was households of control participants in a pulmonary tuberculosis (TB) case-control study carried out in and around Kaski District, Nepal [2,4], with the objective of obtaining 300 participants from households, with a balanced distribution of the three main fuels used in this area in primary stoves for cooking: LPG, wood, and biogas. Participants in the present study were required to be women, who do most of the cooking in Nepal, aged 40-70 years.…”