Small, smart, fast, and cheap
The ability to measure concentrations of small airborne particles is vital in understand adverse health effects from combustion-derived air pollution as well as monitoring trends and the degree of improvement due to control options. Currently available instrumentation necessary to conduct such measurements is generally complex and expensive, as well as requiring trained personnel. Such devices are used routinely in developed countries in mobile laboratories and ambient air monitoring stations, and are well-suited for measurements under controlled laboratory conditions. However, their routine use in real-world household environments, is prohibitively expensive and cumbersome and yet this is where better measurements of human exposure is most needed to pin down health effects. To add to this difficulty, many applications require multiple measurements using several instruments over extended time periods, further adding to cost and complexity. Monitoring locations may also be remote where electrical power is unavailable and security is questionable, so that use of conventional instruments is not possible. In addition, those devices relying on weighing of filter samples, the “gold standard” for particle measurements, produce delayed and even more expensive data because of their need for laboratory work.
Of particular interest to our group in this regard are monitors for use in developing countries to measure particle levels in and around households using solid fuels (biomass and coal). Such fuels are commonly used for cooking and heating, often resulting in high human exposure to particles, and apparently contributing significantly to premature mortality and illness. The lack of suitable instruments for this settings has greatly hampered both health and intervention investigations in these settings.
In an effort fulfill the needs for small, smart, fast, portable, and cheap particle monitors that could be deployed easily in remote, unattended, settings, a commercial smoke detector that combines ionization chamber sensing and optical scattering sensing was identified and modified so that real-time signals could be measured and logged continuously. Through a grant from the Shell Foundation, we laboratory and field tests of these devices since 2003 have now resulted in the “UCB Particle Monitor (UCB),” which has been validated in field trials in Guatemala, Mexico, and India in locations where particle levels are above 50 µg/m3. Two software packages for launching and downloading the devices, and manipulating and storing the data have been developed as well. Journal articles describing the theory, lab tests, and field validation of the UCB are now published (see below).