Abstract:
Indoor air pollution associated with biomass combustion for cooking remains a signifi cant environmental health challenge in rural regions of sub-Saharan Africa; however,
routine monitoring of woodsmoke aerosol concentrations continues to remain sparse.
There is a paucity of field data on concentrations of combustion-generated ultrafine
particles, which efficiently deposit in the human respiratory system, in such environ ments. Field measurements of ultrafine and fine woodsmoke aerosol (diameter range:
10–2500 nm) with field-portable diffusion chargers were conducted across nine wood burning kitchens in Nandi County, Kenya. High time-resolution measurements (1 Hz)
revealed that indoor particle number (PN) and particle surface area (PSA) concentra tions of ultrafine and fine woodsmoke aerosol are strongly temporally variant, reach
exceedingly high levels (PN > 106
/cm3
; PSA > 104
μm2
/cm3
) that are seldom observed in
non-biomass burning environments, are influenced by kitchen architectural features,
and are moderately to poorly correlated with carbon monoxide concentrations. In five
kitchens, PN concentrations remained above 105
/cm3
for more than half of the day due
to frequent cooking episodes. Indoor/outdoor ratios of PN and PSA concentrations
were greater than 10 in most kitchens and exceeded 100 in several kitchens. Notably,
the use of metal chimneys significantly reduced indoor PN and PSA concentrations.