University Report: Ambient Air Pollution, CO, and Child Pneumonia

This report presents a systematic review of the literature investigating the correlation between ambient air pollution, especially carbon monoxide (CO), and the incidence of pneumonia in children. The research question, formulated using the PICO framework, examines whether CO exposure leads to a higher pneumonia rate in children compared to negligible CO exposure. The search strategy included PubMed Central, BioMed Central, and CINAHL databases, with a timeframe of 2014-2020. Keywords such as "air pollution," "carbon monoxide," and "pneumonia in children" were used with Boolean operators to refine the search. Inclusion criteria focused on peer-reviewed articles, recent publications, and specific study designs like systematic reviews and RCTs. Exclusion criteria eliminated irrelevant articles, non-English publications, and those lacking full text. The results, summarized in a table, reveal varying findings, with some studies suggesting a positive association between CO and pneumonia, while others indicate no significant link or attribute pneumonia to other pollutants. The conclusion highlights the inconclusive role of carbon monoxide in causing pneumonia in children, emphasizing the need for further research. The report adheres to the PRISMA guidelines for article selection and provides a comprehensive analysis of the existing literature.

Running head: AMBIENT AIR POLLUTION
CO-induced pneumonia in children
Name of the Student:
Name of the University:
Author Note:

1AMBIENT AIR POLLUTION
Table of Contents
Research question.......................................................................................................................2
Search strategy...........................................................................................................................2
Inclusion and exclusion criteria.................................................................................................5
Inclusion criteria.....................................................................................................................5
Exclusion criteria...................................................................................................................5
Results........................................................................................................................................6
Conclusion................................................................................................................................10
References................................................................................................................................12

2AMBIENT AIR POLLUTION
Research question
In children, does exposure to the air pollutant carbon monoxide lead to pneumonia than air
with negligible or absence of carbon monoxide?
 Patient/population: Children
 Intervention: Exposure to the air pollutant carbon monoxide
 Comparison: Negligible or absence of carbon monoxide in air
 Outcome: pneumonia as the health effect
Search strategy
A systematic review of literature was conducted to to extract the most relevant research
articles to the question under review. This was carried out by searching the medical databases
PubMed Central, BioMed Central and CINAHL as the primary sources of information. The
time frame for the search was set within the range of 2014-2020 to study the most updated
articles and maintain recency of the study. The medical databases listed above were search
using a search terms and a set of keywords, which include “air pollution”, “carbon monoxide
contamination”, “air pollutants”, “CO-induced pneumonia”, “CO inhalation”, “carbon
monoxide exposure”, “pneumonia in children” and “air-borne infection in children”. The use
of the Boolean operators along with the search terms increased the count of search results and
helped in filtering out the irrelevant articles and select only the studies highly suitable to the
review PICO question.
Keywords Keyword Keyword
Keyword 1 air pollution OR air pollutants
Boolean AND
Keyword 2 CO inhalation OR CO-induced pneumonia

3AMBIENT AIR POLLUTION
Boolean AND
Keyword 3 pneumonia in children OR air-borne infection in children
Boolean AND
Keyword 4 carbon monoxide
exposure
AND carbon monoxide contamination
Figure 1: Search terms an the use of Boolean operators
The search results obtained from the input of the above-mentioned keywords and Boolean
operators were narrowed down to the most appropriate and relevant studies on the basis of
the inclusion and exclusion criteria described in the following section for evaluating the
articles further and synthesizing information (Wakefield 2014). The search strategy and
selection of articles can be better understoof by the PRISMA flow chart in the following
figure 2.

4AMBIENT AIR POLLUTION
Figure 2: PRISMA flowchart for selection of articles
Records identified through
medical database searching
(n = 2136)
Sc
re
en
in
g
In
cl
ud
ed
El
igi
bil
ity
Id
en
tif
ic
ati
Additional records identified
through other sources
(n = 187)
Records after duplicates removed
(n = 1756)
Records screened
(n = 184)
Records excluded
(n = 1572)
Full-text articles assessed
for study design
(n = 28)
Full-text articles
excluded
(n = 156)
Studies included in synthesis of
evidence
(n = 5)

5AMBIENT AIR POLLUTION
Inclusion and exclusion criteria
Inclusion criteria
The fundamental inclusion criteria applied to select the most reliable and authentic articles
was including only peer-reviewed articles. The time frame of 2014-2020 was another
important inclusion criteria to ensure that the chosen articles are recent and updated. The
language of the results obtained was limited to enlgish or translatable to english. No specific
geographical location was selected so that the syudies obtained can be generalized and not
bound to specific regions. Articles following the higher levels of study design in the
hieracrchy of evidence were more preferable. The preferred study designs included
systematic reviews, randomized controlled trials (RCTs), and prospective cohort studies to
ensure well-grounded and dependable outcomes of health effect of the exposure carbon
monoxide content in air in this case.
Exclusion criteria
The exclusion criteria was followed to to select articles with valid and reliable information
and eliminate the irrelevant search results. More than one thousand articles were eliminated
that did not fall under the tie period of 2014-2020. This is important to consider statistical
data and the accurate percentage of children affected from pneumonia by inhaling air polluted
with carbon monoxide and form conclusions accordingly. Another set of search results were
eliminated that consisted of editorial papers, unpublished articles and opinion papers to form
the conclusion based on highly credible sources of information. It was also important to
exclude articles published languages other than English or were non-translatable to ennglish
so that the articles can be read and evaluated. Next, the published articles falling within the

6AMBIENT AIR POLLUTION
defined time frame were excluded if they only contained the abstract and the full text was not
available.
The inclusion and exclusion criteria were applied to identify to-the-point articles of high
relevance. To ensure the the reliability of the articles and the information presented in these
articles, only the published articles with study designs at the higher levels of the hierarchy of
evidence were selected. The preferable study design included systematic reviews, randomized
controlled trials and cohort studies (Clarke et al. 2014). Considering data from higher levels
of hierarchy ensured that the interpretations are accurate and correct.
Results
Author
and Year
Research
setting
Study
design
Study
population
Exposure Outcome Bias/
confoundin
g
Results
Nhung et
al.,
(2017)
Hospital-
setting
Systematic
review and
meta-
analyses
Children
hospitalize
d due to
pneumonia
Ambient air
pollution with
particulate
matter PM10.
PM2.5, carbon
monoxide,
sulphur
dioxide and
nitrogen
dioxide.
Prolonged
exposure to
high
ambient air
pollution
markers
positively
associated
with the
admission
of children
to hospitals
Limited
global
generalizabi
lity as the
probable
adverse
effects from
low and
meddle
income
countried
have not
The relation
between
exposure to
ambient air
pollutants
and the
hospitalizati
on rates due
to
pneumonia
among the
different

7AMBIENT AIR POLLUTION
for
pneumonia.
been
considered.
sub-groups
of the study
were similar
and in direct
proportion.
Tuan,
Venâncio
&
Nascime
nto,
(2015)
São José
dos
Campos,
Brazil
Ecological
time series
study
Children
below ten
years of
age
Exposure to
the air pullted
with PM10, CO,
SO2, O3,
humidity
content and
temperature.
Daily data
on the
count of
hospitalizat
ions,
avoidable
hospitalizat
ions and
financial
stress from
the cases
that could
be avoided.
The study is
limited to a
particular
city of São
José dos
Campos and
cannot be
generalized.
The
probably
causes of
pneumonia-
related
hospitalizati
ons can be
attributed to
other
geographica
l reasons
apart from
The mean
hospitalizati
ons due to
pneumonia
per day was
1.47 and
rangd
between
zero and
eleven each
day.

8AMBIENT AIR POLLUTION
air pollution
as well.
Adaji et
al.,
(2019)
Low and
middle
income
countries
Systematic
review of
peer-
reviewd
journals
and
Children
below five
years of
age
The effects of
carbon
monoxide
(CO), solid
fuel,
particulate
matter
(PM)2.5, black
carbon (BC) on
children below
the age of five
causing health
effects such as
pneumonia.
Association
between
exposure to
each of the
major air
pollutants
mentioned
with the
occurrence
of
pneumonia
in children
below five
eyars of
age.
The
selection of
articles for
review
considered
study
designs
placed
lower in the
hierarchy of
evidence
and no time
frame was
defined
which led to
reviewing
old aeticles
as well.
While
sulphur
dioxide and
solid fuel
displayed
significant
association
with
pneumonia
in children,
exposure to
carbon
monoxide
(CO) and
PM2.5 did
not any
association.
Lv et al.,
(2017)
Pediatric
hospital
setting in
Jinan,
China
Case-
crossover
study
design
Patients
under the
age of 15
years,
undergoing
Exposure to
the
contaminants
of air including
inhalable
Evaluation
of the
effect of
air-borne
particles
Inability to
incorporate
to examine
the effects
of
Children of
the age 1-4
years old,
specially
boys are

9AMBIENT AIR POLLUTION
treatment
of
pneumonia.
particles
(PM10), fine
particles
(PM2.5), carbon
monoxide
(CO), sulfur
dioxide (SO2),
nitrogen
dioxide (NO2).
and
pneumonia
-related
hospitalizat
ion.
confounding
factors
causing
pneumonia
due to lack
of
availability
of the data.
more
susceptible
to
hospitalizati
on due to
pneumonia.
Kennedy
et al.,
(2018)
Residenc
e-based
setting
Retrospecti
ve cohort
study
22,441
children
from the
Kaiser Air
Pollution
and
Pediatric
Asthma
Study
belonging
to the age
group of 1-
2 years.
Exposure to air
contaminated
with emissions
from traffic
near the
vicinity of
residential
areas on
children.
Data on
traffic
emissions
were
available
only till
2010.
Some health
effect due to
exposure to
traffic
emission.
The
epidemiolog
ical results
of the study
indicate
associations
between
exposure to
traffic
emissions.
The plausible biological mechanism behind this phenomenon is that carbon monoxide
displaces oxygen and binds to hemoglobin and forms COHb complex, which effectively

10AMBIENT AIR POLLUTION
decreases capacity to carry the oxygen. Besides, when CO binds to Hb at the first of the four
heme sites has an effect on its quaternary structure that results in decreased affinity for
oxygen. Increased COHb causes inflammatory diseases such as pneumonia. As Hb in
children has a higher affinity for CO, they are readily susceptible to acquiring pneumonia
(Chen, Wang & Chunzhi, 2017).
The above findings provide varying effects of CO in causing pneumonia. The study
conducted by Nhung et al., (2017) suggests that CO is positively associated with occurrence
of pneumonia in children and is a significant reason for hospitalization. This is supported by
the study of Tuan, Venâncio & Nascimento, (2015) which concludes that the count of these
hospitalizations may even increase to 11 per day. In addition, Lv et al., (2017) elaborates on
these results by suggesting that the susceptibility of boys is higher than girls and that the
children between 1-4 years are more bvulnerable to pneumonia by CO inhalation that other
groups. However, Adaji et al., (2019) shows that CO has no effect on pneumonia in children
and attributes the cause of pneumonia in children to other contaminants such as sulphur
dioxide and solid fuel. This is similar to the study conducted by Kennedy et al., (2018) which
suggests that emissions of traffic is associated with pneumonia in children but inconclusive of
the role of CO particularly in pneumonia.
Conclusion
In conclusion, it is evident that pneumonia is a growing concern and reason for
hospitalization and deaths among children, which is mainly attributed to ambient air
pollution. The role of carbon monoxide among the contaminants of air is observed by some
studies to be a major contributor of pneumonia in children. It is also observed that children in
the age group of 1-4 years are more susceptible to the infection compared to other age
groups. In contrast, various studies prove that carbon monoxide does not significantly lead to

11AMBIENT AIR POLLUTION
pneumonia in children and other air pollutants are responsible for it. Thus, the role of carbon
monoxide in causing pneumonia is in children is inconclusive.

12AMBIENT AIR POLLUTION
References
Adaji, E. E., Ekezie, W., Clifford, M., & Phalkey, R. (2019). Understanding the effect of
indoor air pollution on pneumonia in children under 5 in low-and middle-income
countries: a systematic review of evidence. Environmental Science and Pollution
Research, 26(4), 3208-3225.
Chen, X., Wang, J., & Chunzhi, H. E. (2017). Levels of heme oxygenase-1 and carbon
monoxide and its significance in the Mycoplasma pneumoniae infection in
children. Chongqing Medicine, 46(5), 626-627.
Clarke, B., Gillies, D., Illari, P., Russo, F. and Williamson, J., 2014. Mechanisms and the
evidence hierarchy. Topoi, 33(2), pp.339-360.
Kennedy, C. M., Pennington, A. F., Darrow, L. A., Klein, M., Zhai, X., Bates, J. T., ... &
Strickland, M. J. (2018). Associations of mobile source air pollution during the first
year of life with childhood pneumonia, bronchiolitis, and otitis media. Environmental
epidemiology (Philadelphia, Pa.), 2(1).
Lv, C., Wang, X., Pang, N., Wang, L., Wang, Y., Xu, T., ... & Li, W. (2017). The impact of
airborne particulate matter on pediatric hospital admissions for pneumonia among
children in Jinan, China: A case-crossover study. Journal of the Air & Waste
Management Association, 67(6), 669-676.
Nhung, N. T. T., Amini, H., Schindler, C., Joss, M. K., Dien, T. M., Probst-Hensch, N., ... &
Künzli, N. (2017). Short-term association between ambient air pollution and
pneumonia in children: A systematic review and meta-analysis of time-series and
case-crossover studies. Environmental Pollution, 230, 1000-1008.

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Tuan, T. S., Venâncio, T. S., & Nascimento, L. F. C. (2015). Air pollutants and
hospitalization due to pneumonia among children. An ecological time series
study. Sao Paulo Medical Journal, 133(5), 408-413.
Wakefield, A., 2014. Searching and critiquing the research literature. Nursing Standard
(2014), 28(39), p.49