Confocal microscopy 3D imaging of diesel particulate matter

Lisa Miyashita,David Wertheim,Gary Foley,Jonathan Grigg,Ian Gill,Gavin Gillmore

doi:10.1007/s11356-021-14025-y

Abstract

To date, diesel particulate matter (DPM) has been described as aggregates of spherule particles with a smooth appearing surface. We have used a new colour confocal microscope imaging method to study the 3D shape of diesel particulate matter (DPM); we observed that the particles can have sharp jagged appearing edges and consistent with these findings, 2D light microscopy demonstrated that DPM adheres to human lung epithelial cells. Importantly, the slide preparation and confocal microscopy method applied avoids possible alteration to the particles’ surfaces and enables colour 3D visualisation of the particles. From twenty-one PM10 particles, the mean (standard deviation) major axis length was 5.6 (2.25) μm with corresponding values for the minor axis length of 3.8 (1.25) μm. These new findings may help explain why air pollution particulate matter (PM) has the ability to infiltrate human airway cells, potentially leading to respiratory tract, cardiovascular and neurological disease.

Highlights

It has been suggested that air pollution is a major cause of premature death and is a recognised risk factor leading to human respiratory disease (Anderson et al 2012, World Health Organization 2018, Khomenko et al 2021)
The impact of air pollution particulate matter (PM) on human health is not restricted to effects in the lungs, with several studies identifying a link with heart disease, neurological disease and adverse pregnancy outcomes (Anderson et al 2012, Klepac et al 2018, Ren et al 2019, Wu et al 2019)
PM released from combustible sources is primarily composed of black carbon (Anderson et al 2012) and is grouped into three main categories based on aerodynamic diameter: PM10 (< 10 μm), PM2.5 (< 2.5 μm) and ultrafine PM (< 1 μm)

Summary

Introduction

It has been suggested that air pollution is a major cause of premature death and is a recognised risk factor leading to human respiratory disease (Anderson et al 2012, World Health Organization 2018, Khomenko et al 2021). The impact of air pollution PM on human health is not restricted to effects in the lungs, with several studies identifying a link with heart disease, neurological disease and adverse pregnancy outcomes (Anderson et al 2012, Klepac et al 2018, Ren et al 2019, Wu et al 2019). Evidence of combustion-derived PM has recently been reported in both brain and heart tissue (Maher et al 2016, Calderon-Garciduenas et al 2019)

Methods

Discussion

Conclusion