Indoor carbon monoxide and PM2.5concentrations by cooking
fuels in Pakistan
Biomass, such as wood, crop residues and dung are
used as cooking fuels by half of the world?s population;
three-fourth of such use occurs in developing countries
(Bruce et al., 2000). Biomass provides 70% of Paki-
stan?s domestic sector energy and 53% of the biomass
energy is from wood (IUCN, 2003; Rehfuess et al.,
2006). Typical traditional biomass stoves can divert up
to 38% of fuel carbon into products of incomplete
combustion, including carbon monoxide (CO), partic-
ulate matter (PM), polycyclic aromatic hydrocarbons,
along with releasing other toxic substances, including
nitric oxides, sulfur dioxide, and formaldehyde (Bruce
et al., 2000; Smith et al., 2000; Zhang and Smith,
Indoor air pollution from biomass fuel is the 8th most
important risk factor, responsible for 2.7% of the
global burden of disease (Smith et al., 2004). In high-
mortality developing countries, indoorsmoke is respon-
sible for an estimated 3.7% of the overall disease
burden, making it the most lethal killer after malnutri-
Abstract In developing countries biomass combustion is a frequently used source
of domestic energy and may cause indoor air pollution. Carbon monoxide (CO)
and particulate matter with an aerodynamic diameter of 2.5 lm or less (PM2.5)
were measured in kitchens using wood or natural gas (NG) in a semi-rural
community in Pakistan. Daytime CO and PM2.5levels were measured for eight
continuous hours in 51 wood and 44 NG users from December 2005 to April
2006. The laser photometer PM2.5(Dustrak, TSI) was calibrated for field
conditions and PM2.5measurements were reduced by a factor of 2.77. CO was
measured by an electrochemical monitor (Model T15v, Langan). The arithmetic
mean for daytime CO concentration was 29.4 ppm in wood users; significantly
higher than 7.5 ppm in NG users (P < 0.001). The arithmetic mean for daytime
PM2.5concentrations was 2.74 mg/m3in wood users; significantly higher than
0.38 mg/m3in NG users (P < 0.001). Higher peak levels of CO and PM2.5were
also observed in wood users. Time spent in the kitchen during fuel burning was
significantly related to increasing CO and PM2.5concentrations in wood users.
These findings suggest that cooking with wood fuel may lead to hazardous
concentrations of CO and PM2.5.
A. R. Siddiqui1,2, K. Lee1,3,
Z. A. Bhutta5, E. B. Gold1
1Department of Public Health Sciences, University of
California at Davis, CA, USA,2Department of
Community Health Sciences, Aga Khan University,
Karachi, Pakistan,3Graduate School of Public Health
and Institute of Health and Environment, Seoul
National University, Seoul, Korea,4Program in
International Nutrition, University of California at Davis,
CA, USA,5Department of Pediatrics, Aga Khan
University, Karachi, Pakistan
Key words: Indoor air quality; Biomass combustion;
Developing country; Wood burning; Kitchen.
Graduate School of Public Health
Seoul National University
28 Yeongun-dong Jongro-gu
Tel.: 82 2 740 8881
Fax: 82 2 745 9104
Received for review 2 April 2008. Accepted for
publication 10 July 2008.
? Indoor Air (2008)
Biomass combustion is frequently used in developing countries for cooking. This study showed very high level of air
pollution in kitchens using wood as the cooking fuel. Many people, especially women and children, are vulnerable to
exposure to very high levels of air pollutants as they spend time in the kitchen during cooking hours.
Indoor Air 2009; 19: 75–82
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? 2008 The Authors
Journal compilation ? Blackwell Munksgaard 2008
have resulted in inadequate statistical power to find
some significant associations. In addition, placing the
sampler in the breathing zone of those likely to be
exposed may not have been uniform in all houses
and that participants required access to their stoves;
however, the variation in this placement among parti-
cipating households is likely to have been random.
This study found that wood users were less-educated,
lived in houses made of a straw or a mix of straw and
bricks with inadequately ventilated kitchens, had a
longer duration of fuel burning, and cooked for longer
duration during fuel burning. Such differences in
populations by fuel type may enhance the vulnerability
of females and perhaps children to high air pollutant
levels which could lead to adverse health effects. This
study demonstrated that women involved in cooking
with biomass are potentially vulnerable to exposure to
high concentrations of CO and PM2.5. Considering the
significant number of women in developing countries,
this is a critical worldwide public health issue.
in such settings. Changes in fuel type, cookingbehavior,
and kitchen practices may bring about the reduction of
indoor air pollutants emitted by cooking fuels.
We acknowledge our participants and field staff. We
are grateful for the support from Department of
Biomedical Engineering Aga Khan University for
technical advice regarding maintenance of air sample
instruments. The study was funded by NIH (5R03
ES13159-2). This project was partially supported by
NIH Research Grant # D43 TW01267 funded by the
Fogarty International Center and the National Insti-
tute of Child Health and Human Development.
Albalak, R., Keeler, G.J., Frisancho, A.R.
and Haber, M. (1999) Assessment of
PM10concentrations from domestic bio-
mass fuel combustion in two rural Boliv-
ian highland villages, Environ. Sci. Tech.,
Balakrishnan, K., Sambandsam, S.,
Ramaswamy, P., Mehta, S. and Smith,
K.R. (2004) Exposure assessment for
respirable particulates associated with
household fuel use in rural district of
Andhra Pradesh India, J. Expo. Anal.
Environ. Epidemiol., 14, S14–S25.
Brauer, M., Barlett, K., RegaladoPineda, J.
and Perez-Padilla, R. (1996) Assessment
of particulate concentrations from
domestic biomass combustion in rural
Mexico, Environ. Sci. Tech., 30, 104–109.
Bruce, N., Perez-Padilla, R. and Albalak, R.
(2000) Indoor air pollution in developing
countries: a major environmental and
public health challenge, Bull. World
Health Organ., 78, 1078–1092.
Bruce, N., McCracken, J., Albalak, R.,
Schei, M., Smith, K.R., Lopez, V. and
West, C. (2004) Impact of improved
stoves, house construction and child
location on levels of indoor air pollution
exposure in young Guatemalan children,
J. Expo. Anal. Environ. Epidemiol., 14,
Dasgupta, S., Huq, M., Khaliquzzaman, M.,
Pandey, K. and Wheeler, D. (2006)
Indoor air quality for poor families: new
evidence from Bangladesh, Indoor Air, 16,
Ezzati, M., Saleh, H. and Kammen, D.M.
(2000) The contributions of emissions and
spatial microenvironments to exposure to
indoor air pollution from biomass
combustion in Kenya, Environ. Health
Perspect., 108, 833–839.
IUCN (2003) Regional Technical Assistance
for Coastal and Marine Resource Man-
agement and Poverty Reduction in South
Asia (ADB Reta 5974). Poverty and
Environment Nexus Study: Rehri Mian,
Korangi Creek area, Pakistan Compo-
nent, Asian Development Bank IUCN-
2003, The World Conservation Union
Khushk, W.A., Fatmi, Z., White, F. and
Kadir, M.M. (2005) Health and social
impacts of improved stoves on rural
women: a pilot intervention in Sindh
Pakistan, Indoor Air, 15, 311–316.
Lohdi, M.A. and Zain-al-Abdin, A. (1999)
Indoor air pollutants produced from fos-
sil fuel and biomass, Energy Conserv.
Manage., 40, 243–248.
McCracken, J.P. and Smith, K.R. (1998)
Emissions and efficiency of improved
wood burning cookstoves in highland
Guatemala, Environ. Int., 24, 739–747.
Naeher, L.P., Leaderer, B.P. and Smith,
K.R. (2000a) Particulate matter and car-
bon monoxide in highland Guatemala:
indoor and outdoor levels from tradi-
tional and improved wood stoves and gas
stoves, Indoor Air, 10, 200–205.
Naeher, L.P., Smith, K.R., Leaderer, B.P.,
Mage, D. and Grajeda, R. (2000b) Indoor
and outdoor PM2.5and CO in high- and
low- density Guatemala villages, J. Expo.
Anal. Environ. Epidemiol., 10, 544–
Naeher, L.P., Smith, K.R., Leaderer, B.P.,
Neufeld, L. and Mage, D.T. (2001)
Carbon monoxide as a tracer for
assessing exposures to particulate
matter in wood and gas cook stove
households of highland Guatemala,
Environ. Sci. Tech., 35, 575–
Park, E. and Lee, K. (2003) Particulate
exposure and size distribution from wood
burning stoves in Costa Rica, Indoor Air,
Rehfuess, E., Mehta, S. and Pruss-Ustun, A.
(2006) Assessing household solid fuel use:
Multiple implications for the millennium
development goals, Environ. Health
Perspect., 114, 373–378.
von Schirnding, Y., Bruce, N., Smith, K.R.,
Ballard-Tremeer, G., Ezzati, M. and
Lvovsky, K. (2002) Addressing the Impact
of Household Energy and Indoor Air Pol-
lution on the Health of the Poor: Implica-
tions for Policy Action and Intervention
Measures, Geneva, Switzerland, World
Siddiqui, A.R., Bhutta, Z., Brown, K.H.,
Lee, K. and Gold, E.B. (2008) Prenatal
exposure to wood fuel smoke and low
birth weight, Environ. Health Perspect.,
Smith, K.R., Samet, J.M., Romieu, I. and
Bruce, N. (2000) Indoor air pollution in
developing countries and acute lower
respiratory infections in children, Thorax,
Smith, K.R., Mehta, S. and Feuz, M.
(2004) Indoor smoke from household
use of solid fuels. In: Ezzati, M., Lopez,
A.D., Rodgers, A. and Murray, C.J.L.
(eds) Comparative Quantification of
Health Risks: The Global Burden of
Disease Due to Selected Risk Factors,
Vol. 2, Geneva, World Health Organi-
Zhang, J. and Smith, K.R. (2005) Indoor
Air Pollution from Household Fuel
Combustion in China: A Review, China,
The 10th international conference on
indoor air quality and climate,
Siddiqui et al.