The association between ambient NO2 and PM2.5 with the respiratory health of school children residing in informal settlements: A prospective cohort study

Toyib Olaniyan; Mohamed Jeebhay; Martin Röösli; Rajen N Naidoo; Nino Künzli; Kees de Hoogh; Apolline Saucy; Mahnaz Badpa; Roslynn Baatjies; Bhawoodien Parker; Joy Leaner; Mohamed Aqiel Dalvie

doi:10.1016/j.envres.2020.109606

The association between ambient NO₂ and PM_2.5 with the respiratory health of school children residing in informal settlements: A prospective cohort study

Environ Res. 2020 Jul:186:109606. doi: 10.1016/j.envres.2020.109606. Epub 2020 Apr 27.

Authors

Affiliations

¹ Centre for Environmental and Occupational Health Research, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa. Electronic address: toyib.olaniyan@canada.ca.
² Centre for Environmental and Occupational Health Research, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa; Division of Occupational Medicine, University of Cape Town, Cape Town, South Africa. Electronic address: Mohamed.jeebhay@uct.ac.za.
³ Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, 4002, Basel, Switzerland; University of Basel, Petersplatz 1, 4003, Basel, Switzerland. Electronic address: martin.roosli@swisstph.ch.
⁴ University of Kwazulu-Natal, Durban, South Africa. Electronic address: naidoon@ukzn.ac.za.
⁵ Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, 4002, Basel, Switzerland; University of Basel, Petersplatz 1, 4003, Basel, Switzerland. Electronic address: nino.kuenzli@swisstph.ch.
⁶ Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, 4002, Basel, Switzerland; University of Basel, Petersplatz 1, 4003, Basel, Switzerland. Electronic address: c.dehoogh@swisstph.ch.
⁷ Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, 4002, Basel, Switzerland; University of Basel, Petersplatz 1, 4003, Basel, Switzerland. Electronic address: apolline.saucy@swisstph.ch.
⁸ Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, 4002, Basel, Switzerland; University of Basel, Petersplatz 1, 4003, Basel, Switzerland. Electronic address: mahnaz.badpa@stud.unibas.ch.
⁹ Centre for Environmental and Occupational Health Research, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa; Department of Environmental and Occupational Studies, Faculty of Applied Sciences, Cape Peninsula University of Technology, Cape Town, 7700, South Africa. Electronic address: baatjiesr@cput.ac.za.
¹⁰ Department of Environmental Affairs and Developmental Planning, Western Cape Government, Cape Town, South Africa. Electronic address: bhawoodien.parker@westerncape.gov.za.
¹¹ Department of Environmental Affairs and Developmental Planning, Western Cape Government, Cape Town, South Africa. Electronic address: joy.leaner@westerncape.gov.za.
¹² Centre for Environmental and Occupational Health Research, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa. Electronic address: aqiel.dalvie@uct.ac.za.

PMID: 32371276
DOI: 10.1016/j.envres.2020.109606

Abstract

Background: No previous epidemiological study has investigated the combined association of long-term ambient nitrogen dioxide (NO₂) and particulate matter of diameter size-2.5 (PM_2.5) exposure with asthma outcomes among schoolchildren in Africa.

Objectives: This study investigated the independent and co-pollutant association of long-term exposures to ambient air pollutants on asthma-associated outcomes in a cohort of schoolchildren in the Western Cape Province of South Africa.

Methods: A total of 590 grade-4 schoolchildren residing in four informal settlements were studied. Spirometry and fractional exhaled nitric-oxide (FeNO) measurements were conducted, including a standardized questionnaire administered to caregivers at baseline and 12-months follow-up. Annual NO₂ and PM_2.5 levels were estimated for each child's home using land-use regression modelling. Single- and two-pollutant models were constructed to assess the independent and co-pollutant association of both air pollutants (NO₂ and PM_2.5) on new cases of asthma-associated outcomes adjusting-for host characteristics, indoor exposures and study area.

Results: The annual average concentration of PM_2.5 and NO₂ were 10.01μg/m³ and 16.62μg/m³ respectively, across the four study areas, and were below the local Standards of 20μg/m³ and 40μg/m³, for both pollutants, respectively. In the two-pollutant-adjusted models, an interquartile range (IQR) increase of 14.2μg/m³ in NO₂ was associated with an increased risk of new onset of ocular-nasal symptoms (adjusted odds ratio-aOR: 1.63, 95% CI: 1.01-2.60), wheezing (aOR: 3.57, 95% CI: 1.18-10.92), more than two or more asthma symptom score (aOR: 1.71, 95% CI: 1.02-2.86), and airway inflammation defined as FeNO > 35 ppb (aOR: 3.10, 95% CI: 1.10-8.71), independent of PM_2.5 exposures.

Conclusion: This study provided evidence that ambient NO₂ levels below local standards and international guidelines, independent of PM_2.5 exposure, increases new cases of asthma-associated outcomes after 12-months.

Keywords: Ambient air pollution; Childhood asthma; Land-use regression; Lung function; Under-researched community.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Air Pollutants* / adverse effects
Air Pollutants* / analysis
Air Pollution* / adverse effects
Air Pollution* / analysis
Child
Environmental Exposure / adverse effects
Environmental Exposure / analysis
Humans
Nitrogen Dioxide / analysis
Particulate Matter / analysis
Particulate Matter / toxicity
Prospective Studies
South Africa / epidemiology

Substances

Air Pollutants
Particulate Matter
Nitrogen Dioxide