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Indian Pediatr 2020;57:1139-1142 |
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Lung Function in
Adolescents Exposed to Environmental Contamination and
Brickworks in Guadalajara, Mexico
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Roberto Hernandez-Raygoza,1 Alberto Tlacuilo-Parra,2
Valery Melnikov3 and Oliver
Mendoza-Cano4
From Department of 1Pediatric Pulmonology and 2Medical Research
Division, UMAE Hospital de Pediatría CMNO, IMSS, Guadalajara, Mexico;
3School of Medicine and 4Faculty of Civil Engineering, University of
Colima, Colima, Mexico.
Correspondence to: Dr Alberto Tlacuilo Parra, Monte Olimpo 1413, Col.
Independencia, C.P. 44340, Guadalajara, Jalisco, México.
Email: [email protected]
Received: November 05, 2019;
Initial review: January 24, 2020;
Accepted: September 03, 2020
Published online: September 16, 2020;
PII: S097475591600245
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Objective: To compare the pulmonary function in adolescents exposed
to different concentrations of air pollutants in two different zones.
Methods: Two zones based on monitoring of environmental pollutant
concentration as high (zone 1) and low (zone 2) were chosen. The lung
functions of apparently healthy adolescents (12-15 years) residing in
two zones were measured for forced vital capacity (FVC), forced
expiratory volume in first second (FEV1), FEV1/FVC ratio, and forced
expiratory flow (FEF)25-75. Results: A total of 302 adolescents
(142, zone 1 and 160, zone 2) resided in the study area, with higher
than permissible concentrations of PM10 and ozone at both places.
Abnormal lung functions were seen in a higher proportion of adolescents
in zone 1 than zone 2 (23% and 14%; P=0.04). A significantly
lower mean (SD) FEV1 was seen in adolescents in zone 1 than zone 2 [2.9
(0.5) vs. 3.2 (0.4) L, P = 0.04]. A higher proportion of
abnormal FEV1/FVC ratio% was seen in zone 1 than 2 (12% vs. 6%,
P=0.04), suggestive of an obstructive pattern on spirometry.
Higher risk (
b
95% CI) for abnormal lung functions was seen with the zone [2.2
(1.1-4.2)], diagnosis of asthma [5.74 (2.4-13.2)], and living within 500
meters from a brickwork [1.8 (1.0-2.5)]. Conclusion: High
exposure to PM10, ozone and living near brickwork were associated with
reduced lung function in adolescents.
Keywords: Air pollution, Asthma, Ozone, Particulate matter,
Spirometry.
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A
round 92% of the global population lives
in areas with environmental contamination that exceeds the
limits recommended by the World Health Organization (WHO), which
includes 300 million children [1,2]. The last phase of pulmonary
development occurs during adolescence with the lungs being
vulnerable to the effects of environmental contami-nation [3].
This may be associated with chronic obstructive pulmonary
disease and lung cancer if persis-tent in adulthood, including
among non-smokers [2,4].
Previous studies [5-7] have demonstrated the
link between environmental contamination and decrease in lung
function in children, with scarce data in adolescents. In the
metropolitan area of Guadalajara, located in the western region
of Mexico, environmental contamination related to automobile
traffic is the primary source of ozone and particulate matter
with an aerodynamic diameter of<10µm (PM10), which exceed the
WHO limits in few areas [8]. The objectives of this study were
to compare the lung functions of adolescents exposed to
different concentrations of atmospheric pollutants and associate
with the proximity to artisan brick factories (brickworks) and
major roadways.
METHODS
This cross-sectional study was conducted
during 2016-2017 in the metropolitan area of Guadalajara,
Mexico. Adolescents between 12 to 15 years of age of either
gender who were attending public secondary schools were
enrolled. Those with active smoking, acute exacerbation of
asthma or acute respiratory infection in the last two weeks were
excluded. The protocol was approved by the Research and Ethics
Committee of the Mexican Social Security Institute.
The metropolitan area of Guadalajara has ten
fixed stations for environmental monitoring which measure PM10,
ozone, nitrogen dioxide (NO 2),
sulfur dioxide (SO2),
and carbon monoxide (CO). Two stations were selected centered on
their concentrations of air pollution (the highest and lowest),
based on the 2016 official report of air quality [8]. Google
earth was used to locate the schools within a 2 km radius from
the monitoring station, and to measure the distance between the
subjects’ homes and brickwork or a major roadway. The
adolescents were randomly selected from a list obtained from the
district’s Department of Education. The study period was from
September to October, 2016 and March to June, 2017 as the mean
values of ozone and PM10 remained stable with maximum of 10%
variation during this period [8].
Written informed consent was obtained from
the parents and assent from the adolescents. Parents completed
an ad hoc questionnaire which included demographic
details, clinical details for chronic diseases, asthma and
allergies, and environmental exposures like prenatal smoke,
secondhand tobacco smoke, wood and charcoal smoke, proximity
(<500 meters) to a major roadway and/or brickworks from their
house.
Height was measured using SECA portable
stadio-meter (SECA GMBH & Co., Hamburg, Germany; model 206), and
weight by Tanita scale (Tanita UK Ltd Middle-sex, United
Kingdom; model UM-061) to calculate the body mass index (BMI).
The spirometer equipment used was Easy-One Spirometer (NDD,
Techopark, Zurich Switzerland) which was calibrated daily with a
3L syringe (Sensor Medics) prior to data collection. Forced
vital capacity (FVC), forced expiratory volume in the first
second (FEV1), FEV1/FVC ratio, and forced expiratory flow 25-75
(FEF25-75) were measured. Readings were performed at the school
during morning and early afternoon to record at least three
acceptable spirograms which were reproducible. The spirometric
measurements were checked with the 2019 American Thoracic
Society (ATS) criteria for acceptability and reproducibility
[9]. The lung function parameters were calculated as mean (SD)
and percentage of the predicted value. Reference values of
National Health and Nutrition Examination Survey III for
Mexican-Americans were used to calculate the percentage of
predicted values [10].
Air pollutant concentrations were measured
for ozone as 8-hour means in parts per million (ppm), PM10 as
24-hour means (µm/m 3),
NO2 as 1-hour means
(ppm), SO2 as
24-hour means (ppm), and CO as 8-hour means (ppm). The
permissible concentrations were defined as per WHO [11], for
ozone, PM10, NO2, SO2,
and CO as <0.050 ppm, <50 µm/m3,
<0.106 ppm, <0.008 ppm and <8.73 ppm, respectively.
Environmental air pollution was considered high (zone 1) or low
(zone 2) according to the median concentrations of pollutants in
the two respective zones.
Sample size and statistical analysis:
The sample size based on a power of >80% and a two-tailed
a
of
0.05, to detect at least an 11% difference [12] in predicted
percentage of FEV1, FVC, and FEV1/FVC ratio between the two
zones was 129 adolescents in each zone.
The analysis was conducted using SPSS V.22
(License by IBM). Comparisons for continuous data between groups
were done with Student t-test, and for proportions by chi-square
test. Logistic regression analysis was done for risk of abnormal
lung functions for factors like zone, diagnosis of asthma, and
living <500 meters from a brickwork. A P-value of less
than 0.05 was considered statistically significant.
RESULTS
A total of 317 adolescents were enrolled, out
of which four children with asthma, two with active smoking and
nine with poor reproducibility on spirometry were excluded to
finally include 302 adolescents. The mean (SD) age in zone 1 (n=142)
and zone 2 (n=160) was 13 (1) and 13 (0.9) years,
respectively, with BMI of 21 (3) and 21 (4) kg/m 2,
respectively.
The mean (SD) concentrations of pollutants in
both zones are shown in Web Table I.
The levels of PM10 and ozone were higher than the permissible
limits in both zones. A higher proportion of adolescents lived
within 500 meters from brickworks in zone 1 than zone 2 (31%
vs. 16%, P= 0.001), respectively. A lesser proportion
of those with allergic rhinitis (2% and 7%, P=0.03) and
asthma (6% and 14%, P=0.03), respectively were reported
in zone 1 than zone 2. There were no significant differences for
any other environmental exposures.
The lung functions of adolescents in both
groups are shown in Table I. A higher proportion
of adolescents in zone 1 had abnormal spirometry results than
zone 2 [23% vs. 14%, OR (95% CI) 1.8 (1.0-3.2); P=0.04].
Significantly higher odds ratio (95% CI) for abnormal lung
function were recorded for the zone, diagnosis of asthma, and
living <500 meters from a brickwork as [2.2 (1.1-4.2)], [5.7
(2.4-13.2)], and [1.8 (1.0-2.5)], respectively.
Table I Lung Function in Adolescents According to Air Pollution Exposure Zone in Guadalajara, Mexico
| Spirometry |
Zone 1 |
Zone 2 |
P value |
| variables |
(n=142) |
(n=160) |
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| FEV1, L |
2.9 (0.5) |
3.2 (0.4) |
0.04 |
| FVC, L |
3.4 (0.6) |
3.3 (0.6) |
0.08 |
| FEF25-75, L/s |
3.7 (0.6) |
3.9 (0.5) |
0.4 |
| % Predicted |
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| FEV1 % |
91.2 (9) |
93.6 (10) |
0.03 |
| FVC % |
90.4 (10) |
91 (0.9) |
0.2 |
| FEV1/FVC % |
86.3 (6) |
86.2 (5) |
0.9 |
| FEF25-75% |
89.2 (3) |
90.1 (4) |
0.6 |
| n (%) |
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| FVC <80 |
16 (11) |
9 (6) |
0.07 |
| FEV1 <80 |
14 (10) |
6 (4) |
0.03 |
| FEV1/FVC ratio |
17 (12) |
9 (6) |
0.04 |
| FEF25-75 <80 |
12 (8) |
8 (5) |
0.3 |
| Continuous data
expressed as mean (SD); FEV1: Forced expiratory volume
in the first second; FVC: Forced vital capacity; FEF
25-75: Forced expiratory flow 25-75. |
DISCUSSION
Almost one-third of the adolescents presented
abnormalities on spirometry, chiefly as a decrease in FEV1 and
predicted FEV1%, which represents obstruction of the medium and
large airways. The pollutants in both the zones were
predominantly PM10 and ozone, both exceeding the WHO
recommendations.
Our study has several limitations. First, we
relied on fixed-site environmental measurements which could
introduce exposure misclassifications. Second, we did not
measure PM 2.5, which accounts for a larger propor-tion of the
combined effects of PM10 and PM 2.5 [13]. PM 2.5 contains more
small particles that can absorb toxic components from the air
and penetrate deep in the lungs [14]. Third, socioeconomic
status might be a determinant of lung function in our population
which was not assessed. Fourth, the questionnaire for pollutant
exposure was not validated. Fifth, we did not perform the
reversibility test on spirometry. Six, multilevel logistic
models should have been adjusted for potential con-founders like
height, BMI, sex, age, and passive smoking.
In this study, up to one third of the
adolescents in zone 1 lived <500 meters from a brickwork. The
brickworks are an artisanal and unregulated industry, initially
located on the periphery, but nowadays found alongside inhabited
zones which emit contaminants like SO 2,
NO2, CO, particulate
matter (PM10 and PM2.5), and black carbon. These can cause
health problems for their workers, in the nearby surrounding and
even distant communities [15]. The generated gases induce an
inflam-matory response in the airways, with excessive mucous
production, broncho-constriction, and deterio-ration of lung
function [16]. The exposure to PM10 and ozone induces oxidative
stress and inflammation of the airway generating a decrease in
lung function in children [17].
Our results are pertinent when compared to
the ESCAPE study [6], from Europe which observed spirometry
alterations in 6.8% to 10.4% children with an annual PM10
ranging from 3.0-31.4 µg/m 3.
The decrease in FEV1 % was associated with high concentrations
of NO2 and PM2.5
[6]. Similarly, the Southern California Children’s Health Study
[5], confirmed alterations in FEV1 and FVC, and progressive loss
of FEV1 <80% of predicted at 15 years of age in 3.6% to 6.3% and
7.9% adolescents on follow-up [5]. Similar reductions in FEV1
and FVC were associated with exposure to ozone, PM10, and NO2
in children in an earlier study [12], as also reported by us.
Exposure to higher NO2
and PM levels during preschool was associated with reduced FEV1
at 16 years of age, but not with FVC which was not modified by
asthma. This suggested that pollutant exposure during early life
was influential to cause increased airway obstruction but not
reduced lung volume in adolescence [18]. The increase in
morbidity and mortality associated with brief exposure to
environmental contamination is also documented [19].
To conclude, the high exposure to PM10,
ozone, and living in close proximity to brickwork was associated
with reduction in lung function in adolescents from the
metropolitan area of Guadalajara. Follow-up studies to determine
the impact of air pollution on lung function during adulthood
are required.
Ethics approval: Comité Local de
Investigación en Salud (CLIS); No. R-2016-1302-031, dated March
06, 2016.
Contributors: RHR, ATP: conception
and designed of the study; RHR, VM: collected the data; RHR,
OMC: analyzed the data; RHR, ATP: wrote the manuscript. All
authors read and approved the final manuscript.
Funding: None; Competing
interest: None stated.
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WHAT THIS STUDY ADDS?
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Adolescents exposed to high concentrations of PM10,
ozone, and living <500 m from a brickwork have reduced
lung function.
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