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< prev - next > Energy Stoves and Ovens KnO 100158_Monitoring Indoor Air Pollution (Printable PDF)
Household smoke monitoring
Practical Action
Monitoring pollution
It is widely agreed that the two major components of biomass smoke that should be monitored are
particulates and carbon monoxide. Particulates are tiny particles of smoke that get deep into the
lungs and make people vulnerable to respiratory infections. Carbon monoxide is a colourless
odourless gas that can lead to death in a very short period of time at high concentrations. At the
lower concentrations commonly experienced in households using traditional stoves and open fires,
exposure can lead to headaches, dizziness and nausea, and it is linked to low birth weight. Where
coal-burning is common, oxides of sulphur may also be measured
Monitoring particulates
One approach to monitoring particulates is to use a low-flow sampling
pump that draws in air, spins off the larger particles and deposits the
lighter, more dangerous ones, on a small circular disc of filter paper.
The filter is weighed before and after monitoring, and the difference
in weight indicates the levels of pollutant in the room .
Monitoring is usually conducted over a whole day. This type of monitor
(made by AP Buck) was used by Practical Action, and is well tried and
tested, but only showed the total levels of pollution over the whole
day. Some versions of this monitor (Figure 3) now measure the levels
of pollution and record them minute by minute over the day (called
‘real-time monitoring’) .
Figure 3: Buck low-
flow sampling pump
A big advantage of this type of monitor is that the white filter paper turns completely black during
monitoring due to the smoke. This filter can be shown to household members to demonstrate
what is happening when they breathe in polluted air. A disadvantage is that the pumping action is
audible within the house during monitoring.
More recently, a small silent monitor has been developed by
University College Berkeley, USA, which produces real time data.
The UCB monitor (Figure 4) relies on sensors from an inexpensive
commercial household smoke detector that combines ionization
chamber sensing (ion depletion by airborne particles) and
photoelectric sensing (optical scattering by airborne particles)
(UCB, 2006).
Monitoring carbon monoxide
Figure 5: T82 Carbon monoxide
time, as shown in Figure 6.
Figure 4: UCB monitor
There are two main types of equipment for monitoring
carbon monoxide in this type of work. The first is a ‘stain
tube’, which is a small tube, made of robust glass inside
which is a sensor which changes colour with exposure to
the gas. These tubes are useful if only a small number of
measurements are to be made, but as they can only be
used once, they are expensive for larger numbers of
samples. They give an indicator of CO levels, but are
difficult to interpret accurately and do not give real time
data. Practical Action uses real time monitoring of carbon
monoxide. The equipment is an ISC-T82 single gas monitor
made by Industrial Scientific (Figure 5). Once monitoring
has taken place, the data can be downloaded to computer
using a T82 datalogger to computer. Software enables the
user to look at graphs of levels of carbon monoxide with