Environmental Epidemiology Review: Health Effects of Air Pollution

This literature review investigates the health effects of air pollution, focusing on studies published between 2010 and 2019. The research question explores the effectiveness of air pollution control measures in improving human health, particularly in urban environments. The search strategy involved using databases such as PubMed, Cochrane Library, and BMJ, employing keywords and Boolean operators to identify relevant articles. The review includes studies with qualitative research designs and geographically based surveys, highlighting the plausible biological mechanisms linking air pollution to respiratory and cardiovascular diseases. Gaps in the literature are identified, particularly concerning the health effects of indoor air pollution, suggesting a need for further research in this area. The review concludes that air pollution significantly impacts human health, emphasizing the importance of government regulations and public awareness to control air pollutants and mitigate both short-term and long-term health consequences.

Running head: Healthcare 1
Environmental Epidemiology
by
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Research question
Are the measures of air pollution control in the cities more effective in the improvement of its
effect on human health?
Population/patient: urban dwellers
Intervention: measures of control of air pollution
Comparison: no measures
Outcome: improved human health
Literature review
Search Strategy
The first stage of carrying out a comprehensive search strategy was by first formulating the
research question which was “Are the measures of air pollution control in the cities more
effective in the improvement of its effect on human health?” The research question was then
broken down into the precise subject areas in order to generate phrases, synonyms, and
keywords. The subject areas include air pollution, human health, urban air pollution, and
measures of air pollution control. The keywords were obtained from the research question
and the synonyms developed from the keywords. The identification of the synonyms was
done with the help of dictionaries and other learning materials. The specific keywords include
urban air pollution, human health, measures of air pollution control, air pollution.
The researcher made use of different phrases and words to explore the specific subject areas,
thus prompting the use of synonyms in addition to keywords during the search in order to
capture all significant research. The specific synonyms used include:
Air pollution – air pollution$, air pollutant$

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Human health – human healt$, human health effect$
Measures of air pollution control – air pollution contro$, measures of contro$
It is important to note that articles like an, a, in, of, or among others were not used together
with the keywords during the search.
After the researcher had identified all the keywords, synonyms and phrases, they were
combined using the Boolean operators ‘AND’, ‘OR’, and ‘NOT’ (Hammer & Rudeanu,
2012). The ‘OR’ operator was used to combine all the synonyms into one search. For
example,
Air pollution – air pollution$ OR air pollutant$
Human health – human healt$ OR human health effects
Measures of air pollution control – air pollution contro$ OR measures of contro$
The ‘AND’ operator was used to combine all items from all the searches.
{Air pollution$ OR air pollutant$} AND {human healt$ OR human health effects} AND {air
pollution contro$ OR measures of contro$}.
The NOT operator was used to exclude items during the search.
{Air pollution$ OR air pollutant$} AND {human healt$ OR human health effects} AND {air
pollution contro$ OR measures of contro$} NOT {Rural}. All the searches that were in
reference to the rural environment were excluded. The articles included in the search were
not more than ten years old (2010-2019).
Four electronic databases were used to identify the most appropriate articles for the review.
These include PubMed, Cochrane Library and BMJ. Medical subject headings (MeSH) were
used alongside the keywords during the search. The search was restricted to articles published

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in the English language. Google Scholar is an example of the internet search engines used to
locate the relevant articles.
A PRISMA flow was used as a guideline in the search strategy as indicated below
Source: (Fleming, Seehra, Polychronopoulou, Fedorowicz, & Pandis, 2012).
IdentificationScreeningEligibilityIncluded
Studies identified through
database search
(n= 10)
Other records identified from
other sources
(n=4 )
No of studiesafter eliminating
duplicates
(n= 6)
Screened articles
(n=6 )
Excluded articles-not
full text
(n=2 )
Full text articles assessed for
eligibility
(n= 4)
Excluded articles-not
addressing air
pollution in urban
(n= 1)
Articles included in the
review
(n=3 )

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Inclusion and Exclusion Criteria
The articles included in the review had to be published in the English language and between
2010 and 2019. The articles obtained had to address the effects of air pollution on human
health. The articles were chosen because they were peer-reviewed thus reducing the
possibility of bias in them. All articles older than 10 years and not in the English language
were excluded from the strategy. Moreover, only 3 research papers were included in the
review because the rest were eliminated after screening and testing for eligibility. The
research designs of the selected articles included qualitative research designs and
geographically based survey. The qualitative design approach is important because it has the
capacity to provide rich information about the participants in addition to providing
comprehensive information on individual cases. However, interpretation in qualitative
research is usually biased due to the influence of the perspective of the researcher (Maxwell,
2012). The survey method is reliable because it’s standardized in the same question and
designed in a similar manner thus making it easy to compare the responses of participants to a
similar question. On the other hand, the survey method is faced with validity because the
standardized questions do not allow the researcher to examine a given topic in details
(Fowler, 2013).
Results of the study
St
ud
y
ID
Author(
s)/Year
Study
Desig
n
Study
Settin
g
Study
populatio
n/sample
size
Expo
sure
varia
ble(s
)
Outcom
e
Variable
(s)
Probable
bias/conf
ounding
if
applicabl
e
Meas
ure of
associ
ation
(e.g.,
OR/R
Summa
ry of
finding
s

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R) if
applic
able
1 Haque
&
Singh,
(2017).
Quali
tative
resea
rch
desig
n
Kolka
ta,
India
residents
near
three
dispensar
ies areas
with
different
ambient
air
pollution
levels
(n=100)
ambi
ent
air
quali
ty
Air
pollution
effects
on
human
health
e.g.
Respirat
ory
diseases,
chronic
obstructi
ve
pulmona
ry
diseases,
Influenz
a, and ,
upper
track
respirato
ry
The
probable
sources
of bias
in the
study
include
the
manner
in which
the
question
naires
are
administ
ered and
designed
.
Perce
ntages
Air
polluti
on
affects
human
health
by
causing
respirat
ory
illness,
chronic
obstruc
tive
pulmon
ary
disease
,
influen
za
among

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infection others
2 Neuber
ger,
Mosha
mmer,
&
Rabcze
nko,
(2013).
Quali
tative
resea
rch
desig
n
Austri
an
Cities
patients
who had
been
transport
ed to
hospitals
in
Linz (n=
n/a)
Expo
sure
to air
pollu
tion
such
as
dome
stic
smok
e
Urban
air
pollution
have
acute
effects
on
cardiopu
lmonary
mortalit
y.
The
study
was
fully
based on
data
collected
previous
ly, thus
its likely
to have
inherent
bias
based on
the
research
methodo
logy
used
Perce
ntiles,
standa
rd
deviat
ions,
mean
NO2
and
small
particle
s
concen
trations
affect
air
polluti
on in
cities.
But
smaller
cities
experie
nce
acute
health
effects
of air
polluti
on
from

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Moto
traffic
3 Stewart
,
Mitchel
l,
Edgerto
&
VanCot
(2015).
Surve
y
Hartf
ord
area,
Conn
ecticu
t
Minority
communi
ties
living
near
pollution
sources
Proxi
mity
to
pollu
tion
sourc
es
Health
effects
as a
result of
living
near
pollution
sources,
and if
the
effects
differ
based on
income,
ethnicity
and sex
The air
pollution
exposure
to the
residents
are
estimate
d in
addition
to the
use of
the
intensitie
s of
pollution
among
other
paramete
rs to
predict
the
respirato
ry
Correl
ation:
ANO
VA
The
study
found
out that
there
was a
signific
ant
correlat
ion
betwee
n
respirat
ory
difficul
ties
with
the
levels
of air
polluti
on,
more

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difficulti
es of
each
participa
nt. This
is likely
to lead
to
observer
bias.
Moreove
r, there
is
confoun
ding
with
proximit
y of
residenc
e to the
pollution
source
being
the
confoun
so
SO2.
Additio
nally,
the
extent
of the
impact
of air
polluti
on
varied
based
on
ethnicit
y, sex,
poverty
, and
age.
The
Hispan
ics
were
the
most

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ding
variable.
affecte
d
Biological Plausibility
The research question has a plausible biological mechanism. There exists a wealth of
scientific theory that supports the relationship between air pollution and its effect on human
health. Multiple studies have shown that exposure to air pollution is likely to cause
respiratory diseases. For instance, the cohort study by Wang Yu, Liu, Wang, Li, Wang, and
Zhang (2016) on 14,126 respondents from different countries found a significant relationship
between the occurrence of asthma and PM25. In addition to respiratory diseases, scientific
studies have also demonstrated that cardiovascular diseases are also associated with air
pollution. The study by Ghorani-Azam, Riahi-Zanjani, and Balali-Mood (2016) on the impact
of air pollution on human health in Iran found out that sulphur dioxide was significant in the
aggravation of cardiovascular disease. Similar findings were also arrived at by Zhou, Li, and
Wang (2018) and Ilyas, Khattak, Nasir, Qurashi, and Durrani (2010).
Gaps in the literature and future research direction
The evidence from the literature review shows that most of the studies have focussed on the
health effects of air pollution in the public or outside the house. Research has shown that
domestic fuel exhaust also contributes to air pollution (Guerreiro, Foltescu, & De Leeuw,
2014; Kim, Jahan, & Kabir, 2011). Thus, there is a need for further research on the health
effects of indoor air pollution. This is because most of the consumers in developing countries
or slum dwellers live in houses with poor air conditioning and even cook in such houses or
rooms. Therefore, it is likely that their vulnerability to disorders caused by air pollution is
high, hence the need for further research on the same.

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Conclusion
Air pollutions have significant effects on human health, triggering, and inducing multiple
illnesses causing increased disabilities and mortalities, especially in the urban. Thus, it is
important that air pollutants are controlled on a priority basis. There is a need for
governments and its policymakers to make laws and regulations that control the level of air
pollutions in addition to creating awareness to its citizens on the effects of air pollution and
control. Air pollution has led to different health effects both for short-term and long-term
exposure. For instance, air pollution causes acute respiratory infections, cancer, stroke,
chronic obstructive pulmonary diseases, Influenza, bronchitis, and asthma. Some of the
measures that can be used to control air pollution include the standardization of motor
vehicles that use fuel as practical as possible, standardization of vehicle engines and the
production of those with low fuel consumption. Public transportation systems can also be
improved by constructing subways and electrical bus pathways.

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