Ultrafine particle exposure and biomarkers of effect on small airways in children

Paul D Robinson; Farhad Salimi; Christine T Cowie; Samuel Clifford; Gregory G King; Cindy Thamrin; Kate Hardaker; Mandana Mazaheri; Lidia Morawska; Brett G Toelle; Guy B Marks

doi:10.1016/j.envres.2022.113860

Ultrafine particle exposure and biomarkers of effect on small airways in children

Environ Res. 2022 Nov;214(Pt 1):113860. doi: 10.1016/j.envres.2022.113860. Epub 2022 Jul 9.

Authors

Affiliations

¹ The Children's Hospital at Westmead, Sydney, Australia; Airway Physiology and Imaging, Woolcock Institute of Medical Research, University of Sydney, Australia; University of Sydney, Sydney, Australia.
² University of Sydney, Sydney, Australia; Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia; Centre for Air Pollution, Energy and Health Research (CAR), Australia.
³ Centre for Air Pollution, Energy and Health Research (CAR), Australia; Respiratory and Environmental Epidemiology, Woolcock Institute of Medical Research, University of Sydney, Australia; South Western Sydney Clinical Campus, University of New South Wales, Australia; Ingham Institute of Applied Medical Research, Sydney, Australia.
⁴ Centre for Air Pollution, Energy and Health Research (CAR), Australia; London School of Hygiene and Tropical Medicine, London, UK; International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Australia.
⁵ Airway Physiology and Imaging, Woolcock Institute of Medical Research, University of Sydney, Australia; University of Sydney, Sydney, Australia.
⁶ Centre for Air Pollution, Energy and Health Research (CAR), Australia; Department of Planning, Industry and the Environment, Sydney, Australia.
⁷ Centre for Air Pollution, Energy and Health Research (CAR), Australia; International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Australia.
⁸ University of Sydney, Sydney, Australia; Respiratory and Environmental Epidemiology, Woolcock Institute of Medical Research, University of Sydney, Australia; Sydney Local Health District, Sydney, Australia. Electronic address: brett.toelle@sydney.edu.au.

PMID: 35820650
DOI: 10.1016/j.envres.2022.113860

Abstract

The small size and large surface area of ultrafine particles (UFP) enhance their ability to deposit in the lung periphery and their reactivity. The Ultrafine Particles from Traffic Emissions and Children's Health (UPTECH) cross-sectional study was conducted in 8-11-year-old schoolchildren attending 25 primary (elementary) schools, randomly selected from the Brisbane Metropolitan Area, Queensland, Australia. Main study findings outlined indirect evidence of distal airway deposition (raised C reactive protein) but as yet, there is no direct evidence in the literature of effects of UFP exposure on peripheral airway function. We present further UPTECH study data from two sensitive peripheral airway function tests, Oscillometry and Multiple Breath Nitrogen Washout (MBNW), performed in 577 and 627 children (88% and 96% of UPTECH study cohort) respectively: mean(SD) age 10.1(0.9) years, 46% male, with 50% atopy and 14% current asthma. Bayesian generalised linear mixed effects regression models were used to estimate the effect of UFP particle number count (PNC) exposure on key oscillometry (airway resistance, (Rrs), and reactance, (Xrs)) and MBNW (lung clearance index, (LCI) and functional residual capacity, (FRC)) indices. We adjusted for age, sex, and height, and potential confounders including socio-economic disadvantage, PM_2.5 and NO₂ exposure. All models contained an interaction term between UFP PNC exposure and atopy, allowing estimation of the effect of exposure on non-atopic and atopic students. Increasing UFP PNC was associated with greater lung stiffness as evidenced by a decrease in Xrs [mean (95% credible interval) -1.63 (-3.36 to -0.05)%] per 1000#.cm^-3]. It was also associated with greater lung stiffness (decrease in Xrs) in atopic subjects across all models [mean change ranging from -2.06 to -2.40% per 1000#.cm^-3]. A paradoxical positive effect was observed for Rrs across all models [mean change ranging from -1.55 to -1.70% per 1000#.cm^-3] (decreases in Rrs indicating an increase in airway calibre), which was present for both atopic and non-atopic subjects. No effects on MBNW indices were observed. In conclusion, a modest detrimental effect of UFP on peripheral airway function among atopic subjects, as assessed by respiratory system reactance, was observed extending the main UPTECH study findings which reported a positive association with a biomarker for systemic inflammation, C-reactive protein (CRP). Further studies are warranted to explore the pathophysiological mechanisms underlying increased respiratory stiffness, and whether it persists through to adolescence and adulthood.

Keywords: Air pollution; Multiple breath washout; Oscillometry.

MeSH terms

Air Pollutants* / adverse effects
Bayes Theorem
Biomarkers
Child
Cross-Sectional Studies
Female
Humans
Male
Particle Size
Particulate Matter* / adverse effects

Substances

Air Pollutants
Biomarkers
Particulate Matter