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Prevalence of respiratory symptoms among children in rural Myanmar-disease burden assessment attributable to household biomass smoke

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More than three billion people continue to rely on solid fuels as their primary source of domestic energy which is associated with elevated concentrations of indoor air pollutants and increased morbidity and mortality both in adults and children. In Myanmar, solid fuel including coal and biomass (such as dung, crop and charcoal) is the main source of energy used in households. A community-based pilot study was conducted in rural Myanmar with the aim to determine the prevalence of childhood respiratory symptoms in association with the use of biomass for cooking. A total of eighty households were recruited and monitored for exposure to particulate matter with size less than 2.5 μm in aerodynamic diameter (PM2.5) and carbon monoxide (CO). In addition, mothers were interviewed to understand their cooking habits, some house characteristics and children’s respiratory health. The study found that PM2.5 and CO were significant contributors for the prevalence of acute respiratory infections and trouble breathing among young children. House characteristics including mosquito coil, associated with children’s respiratory health. The study confirms that domestic environments in developing countries, like Myanmar, continue to have significant health impacts on children.
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Environment
Original Paper
Prevalence of respiratory
symptoms among children in rural
Myanmar-disease burden assessment
attributable to household
biomass smoke
Krassi Rumchev, Thet Win, Dean Bertolatti and
Satvinder Dhaliwal
Abstract
More than three billion people continue to rely on solid fuels as their primary source of domestic
energy which is associated with elevated concentrations of indoor air pollutants and increased mor-
bidity and mortality both in adults and children. In Myanmar, solid fuel including coal and biomass
(such as dung, crop and charcoal) is the main source of energy used in households. A community-
based pilot study was conducted in rural Myanmar with the aim to determine the prevalence of
childhood respiratory symptoms in association with the use of biomass for cooking. A total of eighty
households were recruited and monitored for exposure to particulate matter with size less than 2.5 lm
in aerodynamic diameter (PM
2.5
) and carbon monoxide (CO). In addition, mothers were interviewed to
understand their cooking habits, some house characteristics and children’s respiratory health. The
study found that PM
2.5
and CO were significant contributors for the prevalence of acute respiratory
infections and trouble breathing among young children. House characteristics including mosquito coil,
associated with children’s respiratory health. The study confirms that domestic environments in
developing countries, like Myanmar, continue to have significant health impacts on children.
Keywords
Indoor air pollution, IAQ, solid fuel, biomass energy, respiratory symptoms, children, women,
Myanmar
Accepted: 29 January 2015
Introduction
Over half of the world continues to rely on solid fuels as
the primary source of domestic energy.
1
While the
world population depending on biomass energy is
projected to decline, the rate of decline may not keep
up with population growth and the disadvantaged
status of many developing countries. Currently, the
number of people relying on biomass for cooking and
heating including wood, animal dung, crop waste is
approximately 2.7 billion people and a further 0.4 bil-
lion use coal.
1
During the cooking and heating pro-
cesses, high levels of health-damaging pollutants,
including particulate matter and carbon monoxide,
can be generated.
2
Particulate matter (PM) has been
classified by aerodynamic diameter as size is a critical
health determinant.
3
PM less than 2.5 lm in aero-
dynamic diameter (PM
2.5
) is classified as fine particles
and the combustion of wood and other biomass fuels is
considered as one of their main sources. Fine particu-
late pollution (PM
2.5
) is of specific concern because it
School of Public Health, Curtin University, Perth, Western
Australia, Australia
Corresponding author:
Krassi Rumchev, Curtin University, GPO Box U1987, Perth,
Western Australia 6845, Australia.
Email: k.rumchev@curtin.edu.au
Indoor and Built Environment
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!The Author(s) 2015
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DOI: 10.1177/1420326X15586017
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may contain a high proportion of various toxic metals
and acids, and aerodynamically it can penetrate deeper
into the respiratory tract.
3
There are differences in
exposure levels to biomass smoke and the consequent
health effects; however, young children and their
mothers from developing countries are considered as
the most vulnerable. During cooking activities, young
children are normally carried on their mother’s back or
stay nearby; as a result, they become exposed to higher
levels of potentially harmful indoor air pollutants,
including PM
2.5
and CO.
4
According to Bruce et al.,
5
the average time spent for preparing and cooking meals
may vary; however, it is estimated to be between 3 and
7 h per day. Furthermore, Bruce states that as many as
1 billion people, mostly women and children, are regu-
larly exposed to levels of indoor air pollution that are
up to 100 times higher than those considered acceptable
concentrations. In a report published by the World
Health Organisation (WHO),
2
nearly 2 million people
die prematurely from illness attributable mainly to
indoor air pollution generated from household solid
fuel including asthma, acute respiratory infection
(ARI) and bronchitis. In addition, WHO estimated
that 35.7% of all acute respiratory infections (ARI)
are caused by exposure to smoke generated from burn-
ing solid fuel. The study findings of Smith et al.
6
and
Zelikoff et al.
7
showed that young children living in
homes and using solid fuels for cooking have two or
more times higher risks of suffering from acute lower
respiratory infections (ALRI) than unexposed children.
This is consistent with the results of a study in
Zimbabwe, which reported that children from house-
holds using solid fuel have suffered twice more from
ARI than those from households using LPG/natural
gas or electricity.
8
Similar results were demonstrated
in other studies conducted in other developing coun-
tries.
9,10
In addition, Shi and colleagues established
that early abnormal lung development due to exposure
to poor indoor air quality may be a significant suscep-
tible factor in certain respiratory diseases such as
chronic obstructive pulmonary disease (COPD), cystic
fibrosis (CF) and asthma during childhood or later in
life.
11
WHO estimated that indoor air quality (IAQ)
worldwide is responsible for 2.7% of the global
burden of diseases, and in developing countries IAQ
accounted for 3.7% of the burden of disease, making
it the most significant risk factor after malnutrition,
HIV/AIDS epidemic and lack of safe water and
sanitation.
12
Myanmar is the largest country in the main land of
South East Asia region with a total land area of 676 577
km
2
, and the majority of the country’s population (70%)
resides in rural areas.
13
Domestic utilization of solid fuel
in Myanmar is almost 100%.
14
In 2002, WHO identified
11,590 deaths due to acute lower respiratory infections
(ALRI) in children under five years of age and attributed
to the use of solid fuel in Myanmar.
12
Of all deaths in
Myanmar, 87% occur in rural areas compared to 13% in
urban areas. In addition, the number of COPD deaths
for age 30 and above, attributable to solid fuel use in
Myanmar, was 3070. The estimated total percentage of
national burden of diseases attributable to solid fuel use
in Myanmar is 3.2.
14
To our knowledge, this was the first study of this
kind conducted in Myanmar to investigate indoor air
quality in relation to prevalence of childhood respira-
tory symptoms.
Methods
Study population
The study population consisted of young children, aged
between 9 months and 6 years, and was recruited from
families residing in a village of Hlegu, Yangon Division.
This village represents a typical rural life in the upper
and lower Myanmar agricultural townships that are
dominated by paddy rice cultivation. One hundred
households from five randomly selected villages were
approached and 80 families agreed to participate in the
study. After Curtin University Human Research Ethics
Committee approved the research protocol, a contact
with local authorities of the studied areas in Myanmar
was established and asked for their collaboration. Heads
of the selected villages agreed to advise all residents
about the study and requested their cooperation and
support throughout the project. All prospective partici-
pants were given an information sheet explaining the
study details, and their right to withdraw at any time
during the study, before asked to sign a consent form.
Data collection
Two methods were applied for study data collection –
interview and indoor environmental monitoring. Data
collection took place in June and July 2009.
Interviews
A structured questionnaire, based on the questionnaire
of the American Thoracic Society for respiratory symp-
toms,
15
was used to elicit required data. Some questions
were modified appropriately and made relevant for the
local lifestyle and settings of the study area. The ques-
tionnaire, the consent form and information sheet were
translated in the local language (Burmese) by a team of
local language experts and medical personnel who also
assisted with the interviewing process. Pretest of the
questionnaire was conducted prior to the main study
among five randomly selected families.
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The questionnaire consisted of three parts as the first
part aimed to obtain demographic information of
the families. The second part was related to respiratory
health of the studied children, their older siblings.
Questions included symptoms of cough, wheeze, trou-
ble breathing, running nose, eczema, allergy and
doctor-diagnosed asthma, bronchitis and acute respira-
tory infections. The last part of the questionnaire
comprised information regarding house characteristic
such as age, type of the house, type of floor covering,
presence of windows and fans, place of cooking, kit-
chen size and type of fuels. Questions related to occu-
pants’ activities, cooking habits and smoking inside the
house were also included.
Environmental monitoring
Each participating household was monitored for
concentrations of fine particulate matter with size less
than 2.5 mm in diameter (PM
2.5
) and carbon monoxide
(CO). All measurements were undertaken in kitchens
for approximately 5 h, including the cooking time.
Indoor concentrations of PM
2.5
were measured using
the TSI DustTrack Aerosol Monitor Model 8520,
with size-selective inlet conditioner. This is a real-time
monitor with the flow rate of 1.7 l/min.
16
In addition to
the regular annual factory calibration, the DustTrack
was custom calibrated using the integral 37 mm filter, at
some selected site locations, to determine the gravimet-
ric concentration. The custom calibration factor was
reused at all measurement sites. The levels of exposure
to CO were estimated using Dra
¨eger pump (Model
21/31) as was successfully used in a previous study.
10
The limit of detection (LOD) for CO Dra
¨eger tube was
between 2.47 mg/m
3
and 74 mg/m
3
(10%). Other
indoor parameters such as temperature and humidity
were also monitored using Tinytag-Ultra Data
Loggers. Air velocity inside the house was recorded
by TSI Velocicalc 8345 Anemometer.
Data analysis
Personal and house characteristics of the 80 households
were described using mean (standard deviation) and
median (interquartile range) for continuous variables,
while counts (percentages) were used for categorical
variables. Comparisons of exposure levels of PM
2.5
and CO in relation to personal and house characteris-
tics were assessed using the Independent samples t-test
and Mann–Whitney U test, and Analysis of Variance
and Kruskal–Wallis test. Univariate logistic regression
was used to assess the effects of personal characteristics,
house characteristics and exposure levels of PM
2.5
and
CO, and the likelihood of children reporting respiratory
symptoms (wheeze, trouble breathing and acute
respiratory infections) with adjustments for age and
gender of the child. Multivariable logistic regression
models were also used to assess the joint effects of per-
sonal and house characteristics, exposure levels of
PM
2.5
and CO, and the likelihood of children’s report-
ing respiratory symptoms with adjustments for all vari-
ables. The effects of the personal and house
characteristics, and exposure levels were represented
using odds ratios and associated 95% confidence inter-
vals. P<0.05 was considered to be statistically signifi-
cant. All statistical analyses were performed with IBM
SPSS Statistics Version 21.
Results
Study population
A total of 80 children aged between 9 and 72 months
participated in the study. Most of their mothers (40%)
were middle school leavers, 24% finished high school
and 17% completed primary school. Fifty per cent of
the women in the studied area did not have a job and
stayed at home as housewives. Of all children’s fathers,
36% finished high school, followed by 24% with voca-
tional training and only 12% reached tertiary education.
Most of the men were employed in construction indus-
tries, factories or in farms with an average salary less than
AUD$2 per day. The overall minimum family income was
40,000 Kyat, equivalent to approximately AUD$40 and
maximum of 120,000 Kyat (AUD$120) per month. Of all
households, 44% (35) claimed to be smoke-free houses.
Indoor air pollutants and indoor climate
The mean concentration of PM
2.5
measured in house-
holds kitchens was 472 lg/m
3
(8 lg/m
3
–2050 lg/m
3
)
and for CO the concentration was 4.9 mg/m
3
(<LOD-
15mg/m
3
). The average temperature was 27.8C (23.8–
32.5C) and the relative humidity was 92% (70–100%)
which slightly exceeded the ASHRAE standard 55:2013
recommended guideline values for temperature
(21–26C) and relative humidity (30–70%).
17
The
mean air movement measured in the households was
0.8 m/s (0.1 m/s–2.3 m/s).
House characteristics and related
concentrations of PM
2.5
and CO
The number of people who lived in each house varied
between 3 and 10 with most of the households (64%)
reported five or more family members. Each house had
between one and four rooms; however, only 11%
reported having four rooms.
Of all houses, 40% were built from wood, 39% from
brick and 17% from bamboo with the highest median
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exposure levels of fine particles measured in bamboo
houses (134 mg/m
3
) (Table 1). Majority of households
used zinc sheet and thatch for roofing, and only 6% of
families reported using asbestos in which children were
exposed to higher concentrations of PM
2.5
and CO,
although not significantly different from those who
lived in houses with no asbestos (Table 1). The reported
daily cooking time ranged between 2 h and 4 h, as for
most of families (63%) the cooking time was approxi-
mately 3 h per day. Of all households, 20% used biomass
(coal and firewood) for cooking, and in these houses the
PM
2.5
and CO concentrations were significantly higher
than those that did not use biomass fuel (Table 1).
The use of mosquito coil and smoking inside the
house significantly increased exposure levels of PM
2.5
and CO. Close proximity to busy roads also signifi-
cantly contributed to the indoor concentrations of
fine particles and carbon monoxide (Table 1). As can
be seen from Table 1, there were other house charac-
teristics that had an impact on PM and CO concentra-
tions although with no significant effect.
Prevalence of childhood respiratory
symptoms
The most common reported childhood respiratory
symptoms were cough (90%) followed by runny nose
(78%) and wheeze (76%). Of all children, 51% children
had acute respiratory infections (ARI) and 46%
reported asthma. Other symptoms reported by children
were allergy (39%), bronchitis (35%), eczema (27%),
hay fever (25%) and trouble breathing (24%).
As can be seen from Table 2, children who reported
respiratory symptoms were exposed to higher levels of
fine particulates and carbon monoxide compared to
those who did not report such symptoms although not
all differences were significant. Children with diagnosis
of ARI were exposed to significantly higher concentra-
tions of PM
2.5
while children with trouble breathing
lived in houses with significantly higher concentrations
of CO compared to those who did not report such symp-
toms. Marginally significant differences in PM concen-
trations were measured in households with children who
suffered from allergies, bronchitis and trouble breathing
compared to those who did not have such symptoms.
According to personal communications, most of the
mothers reported a very limited or no knowledge regard-
ing potential adverse health effects associated with
exposures to solid fuel smoke.
House characteristics and prevalence of
respiratory symptoms among children
The study results showed that some house characteris-
tics and elevated concentrations of PM
2.5
and CO
increased the prevalence of childhood respiratory
symptoms (Table 3). Mosquito coil use and exposures
to PM
2.5
and CO were significantly associated with
childhood ARI and the association persisted for mos-
quito coil use after adjusting for all variables. Children
from households that used mosquito coil were approxi-
mately six times more likely to be diagnosed with ARI.
Kitchen size was significantly associated with wheeze
and children who lived in households with kitchens of
4m
3
were approximately four times more likely to
report wheeze symptoms when compared to those
who lived in larger kitchens. Close proximity to a
busy road, smoking and cooking with biomass were
significantly associated with trouble breathing in chil-
dren. The association persisted for households located
near busy roads and cooking with biomass after adjust-
ing for age and gender. Children who lived in houses
located near busy roads and cooked with biomass were
approximately 6 and 10 times more likely to report
trouble breathing, respectively.
Carbon monoxide and PM appeared to be also
strong contributors for prevalence of childhood trouble
breathing as for every unit increase in exposure to CO
and PM, the prevalence of trouble breathing increased
by 19% and 9%, respectively.
Prevalence of respiratory symptoms
among older siblings
Prevalence of respiratory symptoms among older sib-
lings was also high as ARI was the most prevalent
respiratory symptom with 66% followed by asthma
with 35%, shortness of breath and eczema, both with
22%. Households where biomass was the main energy
used for cooking significantly (<0.05) increased the
symptoms of asthma (56%), shortness of breath
(50%) and eczema (40%) among the older siblings
compared to those who lived in households with no
biomass cooking (30%, 16% and 17%, respectively).
In addition, older siblings with asthma and shortness
of breath were exposed to significantly (<0.05) higher
median levels of PM
2.5
(520 mg/m
3
and 609 mg/m
3
) com-
pared to those with no such symptoms (52 mg/m
3
and
51.5 mg/m
3
, respectively). Higher CO concentrations
were also measured in houses with older siblings who
reported respiratory symptoms but the differences were
not significant.
Discussions
This was the first study conducted in Myanmar to
investigate indoor air quality in relation to prevalence
of respiratory symptoms among children. The study
was undertaken in rural areas of Myanmar where
90% of the households still used solid fuel as a major
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Table 1. Exposure levels of PM
2.5
(lg/m
3
) and CO (mg/m
3
) in relation to house characteristics.
Variables n(%)
PM
2.5
PM
2.5
CO CO
Mean SD Median (IQR) Mean SD Median (IQR)
No. of windows
0–1 13 (16.2%) 435.77 548.67 53.00 (23.00, 764.00) 5.03 4.80 4.00 (0.10, 7.00)
2 67 (83.8%) 479.26 614.67 70.00 (30.00, 780.00) 4.90 4.00 5.00 (1.00, 7.00)
p-Value 0.813 0.540 0.920 0.843
Nearby road
No 47 (58.8%) 329.14 502.99 52.00 (24.00, 558.00) 4.31 4.06 4.00 (0.10, 7.00)
Yes 33 (41.2%) 675.94 675.46 409.00 (30.00, 1141.00) 5.81 4.06 5.00 (3.00, 8.00)
p-Value 0.015 0.035 0.108 0.102
Mosquito coil use
No 16 (20.0%) 156.56 285.02 29.50 (19.50, 45.50) 2.62 3.16 0.10 (0.10, 6.00)
Yes 64 (80.0%) 551.10 634.44 318.50 (38.00, 917.50) 5.50 4.13 5.00 (2.50, 8.00)
p-Value <0.001 0.003 0.011 0.011
Smokers at home
No 35 (43.8%) 233.19 366.58 52.00 (27.00, 334.00) 4.11 3.29 4.00 (0.10, 7.00)
Yes 45 (56.2%) 658.09 681.68 454.00 (30.00, 1141.00) 5.56 4.58 5.00 (1.00, 9.00)
p-Value 0.001 0.026 0.104 0.206
Stove type
Open fire 49 (61.2%) 539.65 662.25 55.00 (25.00, 952.00) 4.97 4.48 4.00 (0.10, 8.00)
Stove only 31 (38.8%) 365.57 481.06 70.00 (35.00, 642.00) 4.85 3.50 5.00 (2.00, 7.00)
p-Value 0.178 0.992 0.904 0.784
Kitchen location
Within house 56 (70.0%) 532.83 613.99 318.50 (34.00, 896.00) 5.43 4.29 5.00 (1.50, 8.00)
Outside house 24 (30.0%) 330.71 557.51 52.50 (21.50, 504.50) 3.74 3.43 4.00 (0.10, 6.00)
p-Value 0.170 0.107 0.092 0.102
Cook with biomass
No 64 (80.0%) 314.75 419.83 52.00 (26.00, 614.00) 4.07 3.25 4.00 (0.10, 7.00)
Yes 16 (20.0%) 1102.00 797.17 1388.00 (243.50, 1789.00) 8.33 5.38 9.00 (4.00, 12.50)
p-Value 0.001 <0.001 0.007 0.003
Cook with electricity
No 63 (78.8%) 507.69 613.83 134.00 (29.00, 865.00) 5.17 4.07 5.00 (1.00, 8.00)
Yes 17 (21.2%) 340.65 549.71 47.00 (23.00, 349.00) 4.04 4.24 4.00 (0.10, 6.00)
p-Value 0.312 0.295 0.317 0.277
Kitchen size
4m
3
37 (46.2%) 495.43 593.21 134.00 (29.00, 780.00) 4.92 4.12 5.00 (0.10, 7.00)
>4m
3
43 (53.8%) 452.20 614.59 60.00 (27.00, 689.00) 4.93 4.14 4.00 (1.00, 7.00)
p-Value 0.751 0.885 0.990 0.949
Fan use
No 53 (66.2%) 488.18 615.53 96.80 (27.00, 764.00) 4.97 3.93 5.00 (2.00, 7.00)
Yes 27 (33.8%) 440.81 582.70 53.00 (30.00, 780.00) 4.84 4.50 5.00 (0.10, 8.00)
p-Value 0.741 0.943 0.901 0.861
House type
Brick 31 (38.8%) 461.45 566.40 70.00 (23.00, 811.00) 4.45 3.91 5.00 (0.10, 7.00)
Wood 32 (40.0%) 516.43 673.43 54.45 (29.50, 843.50) 5.33 4.26 5.00 (2.00, 8.00)
Bamboo 17 (21.2%) 408.53 544.94 134.00 (25.00, 647.00) 5.03 4.32 4.00 (0.10, 8.00)
p-Value 0.833 0.810 0.695 0.773
(continued)
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source of energy. This is in agreement with WHO
data
12
showing that around 95% of families who live
in developing countries use solid fuel as a major source
of energy. The mean concentration of PM
2.5
measured
in the current study was 472.2 lg/m
3
which is almost 20
times higher than the WHO recommended guideline
value of 25 lg/m
3
.
18
This is consistent with the findings
of other studies
10
including the study of Ingale and col-
leagues who measured particulate levels in rural India
between 500 lg/m
3
and 18,900 lg/m
3
.
19
This study
showed that number of windows, kitchen size, the use
of incense burner and mosquito coil significantly
increased the indoor particle concentrations and similar
results were established elsewhere.
10,20
According to
Smith and Mehta,
21
a gram of pollution released
indoors is likely to cause many hundreds of times
more exposure than a gram released outdoors.
The present study is similar to others
22–24
demon-
strating that the most common childhood respiratory
symptoms were cough, followed by wheeze, ARI
Table 2. Childhood respiratory symptoms in relation to exposure of PM
2.5
(mg/m
3
) and CO (mg/m
3
).
Variables n(%)
PM
2.5
PM
2.5
CO CO
Mean SD Median (IQR) Mean SD Median (IQR)
Bronchitis
No 52 (65%) 383.00500.00 65.00 (29.25, 628.00) 4.503.9 4.50 (0.1, 7.00)
Yes 28 (35%) 637.00735.00 210.00 (23.25, 1271.50) 5.504.50 5.00 (1.5, 8.00)
p-Value 0.071 0.446 0.344 0.448
Wheeze
No 19 (23.8%) 438.63 620.08 60.00 (38.00, 865.00) 4.91 3.47 5.00 (3.00, 7.00)
Yes 61 (76.2%) 482.65 600.28 96.80 (27.00, 764.00) 4.93 4.31 5.00 (0.10, 8.00)
p-Value 0.782 0.595 0.986 0.900
Asthma
No 43 (54%) 416.9 549.60 60.00 (29, 735) 5.043.97 5.00 (2.00, 7.00)
Yes 37 (46%) 536.46658.24 134 (26.00, 886.00) 4.904.29 5.00 (0.1, 8.00)
p-Value 0.385 0.802 0.779 0.807
Allergies
No 49 (61%) 371.51538.10 49.00 (26.00, 688.50) 4.624.02 4.00 (0.1, 7.00)
Yes 31 (39%) 631.31668.10 454.00 (40.00, 1355.00) 5.414.25 6.00 (1.00, 8.00)
p-Value 0.059 0.078 0.404 0.316
Trouble breathing
No 61 (76.2%) 388.49 509.15 55.00 (27.00, 689.00) 4.26 3.53 4.00 (0.10, 7.00)
Yes 19 (23.8%) 740.95 789.36 367.00 (33.00, 1461.00) 7.07 5.11 7.00 (3.00, 12.00)
p-Value 0.080 0.091 0.034 0.035
ARI diagnosis
No 39 (48.8%) 305.15 476.95 47.00 (23.00, 558.00) 4.06 3.86 3.00 (0.10, 7.00)
Yes 41 (51.2%) 631.10 667.11 409.00 (38.00, 1139.00) 5.75 4.20 5.00 (3.00, 8.00)
p-Value 0.014 0.009 0.065 0.081
Table 1. Continued.
Variables n(%)
PM
2.5
PM
2.5
CO CO
Mean SD Median (IQR) Mean SD Median (IQR)
Type of roofing
Thatch 26 (32.5%) 519.23 745.75 50.50 (21.75, 1034.00) 4.91 4.40 3.50 (0.1, 8.00)
Zinc sheet 49 (61%) 411.46 483.93 96.80 (31.50, 749.50) 4.84 3.83 5.00 (1.00, 7.00)
Asbestos 5 (6.3%) 822.8 801.90 735.00 (54.00, 1635.50) 5.84 5.88 7.00 (0.1, 11.00)
p-Value 0.311 0.296 0.876 0.660
6Indoor and Built Environment 0(0)
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and asthma. ARI is a serious problem in Myanmar and
51% of the studied children reported this illness while
among their older siblings the prevalence of ARI was
66%. These results are consistent with the study by
Smith et al.
6
who claimed that the acute respiratory
infection is one of the most common causes of illness
in children and a major cause of death in the world. In
most households, the median exposure levels of CO
were within the WHO recommended guideline value;
however, the study found that carbon monoxide was
a significant contributor for prevalence of ARI along
with fine particulate matter. Exposure to PM
2.5
and CO
also significantly increased the prevalence of trouble
breathing. These results are consistent with the findings
of studies undertaken elsewhere. A study in Kenya
9
showed that exposure to particulate matter was a sig-
nificant contributing factor for increased incidence of
respiratory symptoms among children. Increased
prevalence of childhood respiratory symptoms was
also associated with exposures of particulates and
carbon monoxide in studies from China, South
Pakistan, India and Zimbabwe.
10,19,25,26
Consistent with previous findings,
8,27
the current
study showed that house characteristics can also con-
tribute to increased prevalence of childhood respiratory
health including mosquito coil for ARI and kitchen size
for wheeze. Cooking with biomass, smoking inside the
house and nearby busy road significantly increased the
prevalence of trouble breathing in young children and
increased the prevalence of asthma, shortness of breath
and eczema among older siblings which has also been
demonstrated in other studies.
21,26,27
There were some limitations related to this study
which are acknowledged by authors. First, confound-
ing factors such as age and gender were considered in
the logistic regression model; however, the authors
acknowledge that other factors including nitrogen
oxides (NOx) and not measured in the current study,
could affect the association between respiratory
symptoms and indoor air pollution. The second limita-
tion was related to the diagnosis of asthma and bron-
chitis which may vary from country to country. In
order to minimise this limitation, local trained medical
professionals were asked to assist with the interview
process of the study population. It is also acknowl-
edged that the small sample size, due to time and
resource constraints, is a limitation and therefore
resulted in a study with a lower statistical power.
Finally, the DustTrak particle monitor may cause
biased particle concentration readings in conditions of
extreme temperatures and high relative humidity
(>80%). Since the average recorded relative humidity
was 70% and the average temperature was 26C, it is
believed that the DustTrak provided accurate readings.
Conclusion
The study confirms that domestic environments in
developing countries, like Myanmar, continue to have
significant health impacts on women and children. The
burden of disease as a result of poor indoor air quality
is likely to be high and requires further studies and
interventions. In 2006, WHO unveiled indoor air pol-
lution from burning solid fuel as one of the top global
health risk, and yet the most recent and more accurate
estimates show practically no change.
28
Practical solutions to the household energy problem
do exist including switching from a traditional stove to
an improved stove. Household energy projects are cur-
rently under way around the world and some have been
Table 3. Odds ratios with 95% confidence intervals of respiratory symptoms in relation to house characteristics
and for unit increase in exposure levels of PM
2.5
(mg/m
3
) and CO (mg/m
3
).
ARI diagnosis
Variables Univariate
a
Multivariable
b
Mosquito coil use 6.24 (1.61–24.25), p¼0.008 6.24 (1.61–24.25), p¼0.008
PM
2.5
1.11 (1.02–1.21), p¼0.020 n.s.
CO 1.12 (1.00–1.26), p¼0.054 n.s.
Wheeze
Kitchen size 4.16 (1.19–14.52), p¼0.026 4.16 (1.19–14.52), p¼0.026
Trouble breathing
Nearby road 6.21 (1.95–19.77), p¼0.002 6.46 (1.74–23.92), p¼0.005
Smokers at home 5.81 (1.53–22.05), p¼0.010 n.s.
Cook with biomass 10.27 (2.96–35.67), p<0.001 10.67 (2.66–42.77), p¼0.001
PM
2.5
1.09 (1.01–1.19), p¼0.036 n.s.
CO 1.19 (1.04–1.36), p¼0.014 n.s.
p-value is significant at <0.05.
Rumchev et al. 7
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very successful. As an example, the Chinese National
Improved Stove Program focused on improving stoves
by increasing air flow or installing chimneys or flues.
This national program has accomplished an unprece-
dented scale of rural energy intervention, distributing
more than 180 million improved stoves.
27
Several other
intervention studies also documented reduction in
indoor air pollution levels including the study in
Guatemala which was the most sophisticated interven-
tion undertaken to date.
29
In addition, changing behaviour using education and
awareness programmes can also play an important role
in reducing exposures of indoor smoke in rural
Myanmar.
Authors’ contribution
All authors contributed equally in the preparation of this
manuscript. I declare that there was no conflict of interest
in relation to the work of this paper.
Acknowledgments
The authors would like to thank all participants and volun-
teers for their contribution to this study.
Declaration of conflicting interests
The authors declared no potential conflicts of interest with
respect to the research, authorship, and/or publication of this
article.
Funding
This research received no specific grant from any funding
agency in the public, commercial, or not-for-profit sectors.
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Around 50% of people, almost all in developing countries, rely on coal and biomass in the form of wood, dung and crop residues for domestic energy. These materials are typically burnt in simple stoves with very incomplete combustion. Consequently, women and young children are exposed to high levels of indoor air pollution every day. There is consistent evidence that indoor air pollution increases the risk of chronic obstructive pulmonary disease and of acute respiratory infections in childhood, the most important cause of death among children under 5 years of age in developing countries. Evidence also exists of associations with low birth weight, increased infant and perinatal mortality, pulmonary tuberculosis, nasopharyngeal and laryngeal cancer, cataract, and, specifically in respect of the use of coal, with lung cancer. Conflicting evidence exists with regard to asthma. All studies are observational and very few have measured exposure directly, while a substantial proportion have not dealt with confounding. As a result, risk estimates are poorly quantified and may be biased. Exposure to indoor air pollution may be responsible for nearly 2 million excess deaths in developing countries and for some 4% of the global burden of disease. Indoor air pollution is a major global public health threat requiring greatly increased efforts in the areas of research and policy-making. Research on its health effects should be strengthened, particularly in relation to tuberculosis and acute lower respiratory infections. A more systematic approach to the development and evaluation of interventions is desirable, with clearer recognition of the interrelationships between poverty and dependence on polluting fuels.
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BACKGROUND—A critical review was conducted of the quantitative literature linking indoor air pollution from household use of biomass fuels with acute respiratory infections in young children, which is focused on, but not confined to, acute lower respiratory infection and pneumonia in children under two years in less developed countries. Biomass in the form of wood, crop residues, and animal dung is used in more than two fifths of the world's households as the principal fuel. METHODS—Medline and other electronic databases were used, but it was also necessary to secure literature from colleagues in less developed countries where not all publications are yet internationally indexed. RESULTS—The studies of indoor air pollution from household biomass fuels are reasonably consistent and, as a group, show a strong significant increase in risk for exposed young children compared with those living in households using cleaner fuels or being otherwise less exposed. Not all studies were able to adjust for confounders, but most of those that did so found that strong and significant risks remained. CONCLUSIONS—It seems that the relative risks are likely to be significant for the exposures considered here. Since acute lower respiratory infection is the chief cause of death in children in less developed countries, and exacts a larger burden of disease than any other disease category for the world population, even small additional risks due to such a ubiquitous exposure as air pollution have important public health implications. In the case of indoor air pollution in households using biomass fuels, the risks also seem to be fairly strong, presumably because of the high daily concentrations of pollutants found in such settings and the large amount of time young children spend with their mothers doing household cooking. Given the large vulnerable populations at risk, there is an urgent need to conduct randomised trials to increase confidence in the cause-effect relationship, to quantify the risk more precisely, to determine the degree of reduction in exposure required to significantly improve health, and to establish the effectiveness of interventions.
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