A comparative study of human exposures to household air pollution from commonly used cookstoves in Sri Lanka

Abstract

Solid fuel burning cookstoves are a major source of household air pollution (HAP) and a significant environmental health risk in Sri Lanka. We report results of the first field study in Sri Lanka to include direct measurements of both real-time indoor concentrations and personal exposures of fine particulate matter (PM ) in households using the two most common stove types in Sri Lanka. A purposive sample of 53 households was selected in the rural community of Kopiwatta in central Sri Lanka, roughly balanced for stove type (traditional or improved 'Anagi') and ventilation (chimney present or absent). At each household, 48-h continuous real-time measurements of indoor kitchen PM and personal (primary cook) PM concentrations were measured using the RTI MicroPEM personal exposure monitor. Questionnaires were used to collect data related to household demographics, characteristics, and self-reported health symptoms. All primary cooks were female and of an average age of 47 years, with 66% having completed primary education. Median income was slightly over half the national median monthly income. Use of Anagi stoves was positively associated with a higher education level of the primary cook (P = 0.026), although not associated with household income (P = 0.18). The MicroPEM monitors were well-received by participants, and this study's valid data capture rate exceeded 97%. Participant wearing compliance during waking hours was on average 87.2% on Day 1 and 83.3% on Day 2. Periods of non-compliance occurred solely during non-cooking times. The measured median 48-h average indoor PM concentration for households with Anagi stoves was 64 μg/m if a chimney was present and 181 μg/m if not. For households using traditional stoves, these values were 70 μg/m if a chimney was present and 371 μg/m if not. Overall, measured indoor PM concentrations ranged from a minimum of 33 μg/m to a maximum of 940 μg/m , while personal exposure concentrations ranged from 34 to 522 μg/m . Linear mixed effects modeling of the dependence of indoor concentrations on stove type and presence or absence of chimney showed a significant chimney effect (65% reduction; P < 0.001) and an almost significant stove effect (24% reduction; P = 0.054). Primary cooks in households without chimneys were exposed to substantially higher levels of HAP than those in households with chimneys, while exposures in households with traditional stoves were moderately higher than those with improved Anagi stoves. As expected, simultaneously measuring both indoor concentrations and personal exposure levels indicate significant exposure misclassification bias will likely result from the use of a stationary monitor as a proxy for personal exposure. While personal exposure monitoring is more complex and expensive than deploying simple stationary devices, the value an active personal PM monitor like the MicroPEM adds to an exposure study should be considered in future study designs.

Possible Mediation by Methylation in Acute Inflammation Following Personal Exposure to Fine Particulate Air Pollution

“…A rubber intake tube draws air from the breathing zone of the wearer (see Web Figure 2 MicroPEM reportedly correlates well (R 2 > 0.99) with the TSI DustTrak (Shoreview, Minnesota) (27). We also attached a HOBO Data Logger (Onset Computer Corporation, Bourne, Massachusetts) on the rings of the vest to simultaneously monitor local temperature and relative humidity (Web Figure 2).…”

Sri Lanka Pilot Study to Examine Respiratory Health Effects and Personal PM2.5 Exposures from Cooking Indoors

“…The recruitment effort and purposive sampling yielded 53 households with women who cooked and were willing to participate in the exposure study. For a detailed description of the study design and data collection see Chartier et al [13]. …”

“…During the 48 h monitoring period, the field team deployed the MicroPEM exposure monitors and recorded stove, chimney, and cooking area measurements and features. They also asked the cook questions about the demographic characteristics of her household and cooking practices [13]. …”

“…Details about the study design and the results of exposure monitoring are presented in a previous publication [13]. That paper reported that indoor PM 2.5 concentrations were reduced by 65% when a chimney was present ( p < 0.001) and by 25% ( p = 0.054) when an Anagi stove (versus a Traditional stove) was used.…”

“…That paper reported that indoor PM 2.5 concentrations were reduced by 65% when a chimney was present ( p < 0.001) and by 25% ( p = 0.054) when an Anagi stove (versus a Traditional stove) was used. Furthermore, personal PM 2.5 concentrations were slightly higher than indoor PM 2.5 concentrations at low indoor concentration levels but much lower at high indoor concentration levels, presumably because the cook moved away from the stove when the smoke was intolerable [13]. The current manuscript describes the observed association between self-reported respiratory health conditions of the primary cook, and children residing in her household, and personal and indoor PM 2.5 concentrations influenced by stove and kitchen area characteristics.…”