The use of bluetooth low energy Beacon systems to estimate indirect personal exposure to household air pollution

Abstract

Household air pollution (HAP) generated from solid fuel combustion is a major health risk. Direct measurement of exposure to HAP is burdensome and challenging, particularly for children. In a pilot study of the Household Air Pollution Intervention Network (HAPIN) trial in rural Guatemala, we evaluated an indirect exposure assessment method that employs fixed continuous PM 2.5 monitors, Bluetooth signal receivers in multiple microenvironments (kitchen, sleeping area and outdoor patio), and a wearable signal emitter to track an individual's time within those microenvironments. Over a four-month period, we measured microenvironmental locations and reconstructed indirect PM 2.5 exposures for women and children during two 24-h periods before and two periods after a liquefied petroleum gas (LPG) stove and fuel intervention delivered to 20 households cooking with woodstoves. Women wore personal PM 2.5 monitors to compare direct with indirect exposure measurements. Indirect exposure measurements had high correlation with direct measurements (n = 62, Spearman ρ = 0.83, PM 2.5 concentration range: 5-528 µg/m 3). Indirect exposure had better agreement with direct exposure measurements (bias: −17 µg/m 3) than did kitchen area measurements (bias: −89 µg/m 3). Our findings demonstrate that indirect exposure reconstruction is a feasible approach to estimate personal exposure when direct assessment is not possible.

Attributing Air Pollutant Exposure to Emission Sources with Proximity Sensing

“…Based on Bluetooth Low Energy (BLE) Beacon technology, we developed this proximity sensing system using commercially available BLE Beacons to estimate the user's distance to the cooking area (time-activity data) and therein attribute exposure to a source and improve personal-to-cooking area pollution modeling. Since the development and implementation of our system, additional validation work has been conducted using principles of the system in Guatemala [10] with expressed interest in modeling exposure using an array of low-cost sensors [11].…”

Air Pollutant Exposure and Stove Use Assessment Methods for the Household Air Pollution Intervention Network (HAPIN) Trial

“…The system was piloted by the four sites and found to be acceptable to participants. Specific results from our formative work indicated that indirect exposure measurements had high correlation with direct personal measurements for adult women cooking with either gas or solid fuel (n = 62, Spearman q = 0:83, PM 2:5 concentration range: 5-528 lg=m 3 ), and indirect measurements had better agreement with direct measurements (bias: −17 lg=m 3 ) compared with kitchen area measurements (bias: −89 lg=m 3 ) (Liao et al 2019). Performance of the Beacon localization approach is also checked via a walk-through procedure by the field enumerators after installation of the loggers and receivers in the home, but before sampling begins.…”

“…The microenvironmental approach is used because even with the small size of the ECM, it is still impractical for use on young infants. The approach used here is similar to previous efforts (Balakrishnan et al 2004;Ezzati et al 2000;Saksena et al 2003;Zuk et al 2007) but adds an objective measure of location with the Beacons by tracking where the child is over 24 h (Piedrahita et al 2019b;Liao et al 2019). Objective measures of location are key for using this approach because participant recall of time-activity patterns can be unreliable and are often biased (Daum et al 2018).…”

“…Results from the HAPIN formative work in Guatemala have shown that the Beacon system provides accurate time-location patterns, and this microenvironmental approach can predict personal exposure better compared with a single area measurement (Liao et al 2019). The system was piloted by the four sites and found to be acceptable to participants.…”

Design and Rationale of the HAPIN Study: A Multicountry Randomized Controlled Trial to Assess the Effect of Liquefied Petroleum Gas Stove and Continuous Fuel Distribution

“…Personal exposures for the child are estimated by integrating corresponding area concentrations with time spent in the respective locations along with time spent near the mother, who is instrumented with an ECM and receiver whenever feasible. Details of this approach can be found in Liao et al (2019), which presents results from piloting the indirect assessment with proximity beacons for the HAPIN trial in Guatemala.…”