Vascular Responses Among Adults Four Years Post Exposure to 6 Weeks of Smoke from the Hazelwood Coal Mine Fire

Abstract

Background and Aims

Mega-wild fires are exposing large communities to weeks or months of high concentration smoke-related fine particulate air pollution (PM). However, little research has examined the long-term vascular responses from exposure to PM of this concentration and duration. We investigated whether level of exposure to 6 weeks of PM from the 2014 Hazelwood coal mine fire was associated with abnormal vascular responses approximately four years later.

Methods

A cross-sectional analysis was undertaken of 387 participants (225 exposed, 162 unexposed) aged 55–89 years, 3.5–4 years after the mine fire. The primary outcome was flow-mediated dilatation (FMD), with time to reach peak diameter as the secondary outcome. Other secondary markers included high-sensitivity C-reactive protein (hsCRP) and ischaemic Electrocardiogram (ECG) changes.

Results

There was no evidence of a difference in FMD between participants with high, medium, low or no mine-fire related PM_2.5 exposure (4.09% vs 4.06% vs 4.02% vs 3.98%, respectively, p=0.99). Likewise, there was no difference in hsCRP or ischaemic ECG changes. In contrast, there was evidence of a difference in time to peak diameter (p=0.002) with more unexposed participants reaching peak diameter within 30 seconds (36%) compared to those who had high, medium, or low exposure (23%, 22%, 13%, respectively). Multivariate ordinal logistic regression analysis suggested that township, Morwell (exposed) vs Sale (unexposed), but not level of PM_2.5 exposure, was associated with delayed time to peak diameter (OR 2.71; 95% CI 1.56, 4.69). Smokers also had delayed time to peak diameter.

Conclusion

There was no association between level of exposure to PM_2.5 from the 6-week Hazelwood coal mine fire smoke event and reduced FMD, elevated hsCRP or ischaemic ECG four years later. Evidence of delayed time to peak diameter observed in adults from the exposed town, compared to an unexposed town, requires further investigation.

Keywords:

• vascular responses
• flow mediated dilatation
• time to peak diameter
• particulate matter
• epidemiology
• air pollution

Acknowledgments

The Victorian Department of Health funded the Hazelwood Health Study. However, the paper presents the views of the authors, not the Department. We would like to acknowledge Brigitte Borg, Sharon Harrison, Karen Kilpatrick, Shantelle Allgood, Susan Denny, Sylvia Pomeroy, Melanie Reeves, Kylie Sawyer and Kristina Thomas for their assistance with project management, procurement, recruitment and data collection.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

Michael J Abramson holds investigator-initiated grants for unrelated research from Pfizer, Boehringer-Ingelheim, Sanofi and GSK. He has also undertaken an unrelated consultancy for Sanofi and received a speaker’s fee from GSK. Danny Liew has undertaken unrelated consultancies for AbbVie, Astellas, AstraZeneca, Bristol-Myers Squibb, CSL-Behring, Novartis, Pfizer and Sanofi. Dion Stub undertakes unrelated research supported by a National Heart Foundation fellowship. The remaining authors report no relationships that could be construed as a conflict of interest in this work.

Additional information

Funding

This study was funded by the Victorian Department of Health. The paper presents the views of the authors and does not represent the views of the Department.