An Inexpensive Dual-Chamber Particle Monitor: Laboratory Characterization

Abstract

In developing countries, high levels of particle pollution from the use of coal and biomass fuels for household cooking and heating are a major cause of ill health and premature mortality. The cost and complexity of existing monitoring equipment, combined with the need to sample many locations, make routine quantification of household particle pollution levels difficult. Recent advances in technology, however, have enabled the development of a small, portable, data-logging particle monitor modified from commercial smoke alarm technology that can meet the needs of surveys in the developing world at reasonable cost. Laboratory comparisons of a prototype particle monitor developed at the University of California at Berkeley (UCB) with gravimetric filters, a tapered element oscillating microbalance, and a TSI DustTrak to quantify the UCB particle monitor response as a function of both concentration and particle size and to examine sensor response in relation to changes in temperature, relative humidity, and elevation are presented here. UCB particle monitors showed good linearity in response to different concentrations of laboratory-generated oleic acid aerosols with a coarse (mass median diameter, 2.1 m) and fine (mass median diameter, 0.27-0.42 m) size distributions (average r 2 ϭ 0.997 Ϯ 0.005). The photoelectric and ionization chamber showed a wide range of responses based on particle size and, thus, require calibration with the aerosol of interest. The ionization chamber was five times more sensitive to fine rather than coarse particles, whereas the photoelectric chamber was five times more sensitive to coarse than fine. The ratio of the response between the two sensors has the potential for mass calibration of individual data points based on estimated parameters of the size distribution. The results demonstrate the significant potential of this monitor, which will facilitate the evaluation of interventions (improved fuels, stoves, and ventilation) on indoor air pollution levels and research on the impacts of indoor particle levels on health in developing countries.

Household Air Quality Risk Factors Associated with Childhood Pneumonia in Urban Dhaka, Bangladesh

“…The UCB particle monitor has been validated in laboratory and household-level applications. 3,10,11 We used a random number function in Microsoft Excel (Microsoft Corp.) to choose one-half of the case and control households for measurement of PM 2.5 concentrations; we relied on the random selection process to maintain an~2:1 ratio of controls to cases among the subset of households with PM 2.5 measurement. In these households, we sought to measure PM 2.5 in the cooking space and the living area where the child was reported to sleep.…”

An inexpensive light-scattering particle monitor: field validation

“…The light-scattering chamber discussed here uses a light-emitting diode (LED) with an output wavelength of 880 nm and a photodiode that measures the intensity of scattered light at an angle of 45° from the forward direction. Although the UCB does not select particles using a traditional size cut device (cyclone or impactor), the photoelectric sensor is most sensitive to particles less than 2.5 mm in aerodynamic diameter (PM 2.5 ) and the ionization sensor is most sensitive to particles less them 1.0 μm.1 † Temperature correction and data filtering were as described in Edwards et al 2 Briefly, the 1 min logged values represent a weighted moving average of the previous sixty 1 s particle concentrations. Temperatures were recorded every 15 s and averaged for 1 min logged values.…”

Laboratory Evaluation and Calibration of Three Low-Cost Particle Sensors for Particulate Matter Measurement

“…The PPD42NS sensor and GP2Y1010AU0F sensor have also been packaged in commercialized particle monitors, such as the AirAssure PM 2.5 Indoor Air Quality Monitor (TSI Inc.), which was tested in this study, the Air Box TM (Haier Inc.), and the Pervasive Air-Quality Monitor (PAM, Air-Scientific). To fulfill the need for smaller, cheaper, and more accurate particle monitors, other sensors have also been designed (Litton et al 2004;Chowdhury et al 2007), calibrated (Edwards et al 2006), and applied in field studies (Chowdhury et al 2007;Sahu et al 2011).…”