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Dr Fiona Foo General and interventional cardiologist , Sydney Cardiology Group and MQ Health Cardiology , Macquarie University Hospital , Sydney Adventist Hospital and Norwest Private Hospital , Sydney , NSW .
Copyright © 2021 Australian Doctor All rights reserved . No part of this publication may be reproduced , distributed , or transmitted in any form or by any means without the prior written permission of the publisher . For permission requests , email : howtotreat @ adg . com . au .
First published online on 22 January 2021
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INTRODUCTION
CLIMATE change is adversely affecting human health and is expected to lead to further future increases in morbidity and mortality . 1 , 2 While COVID-19 dominated 2020 , we cannot deny the overwhelming evidence that earth is facing a climate emergency . 3
Since the 1970s , the world has
observed a 1 ° C temperature rise above pre-industrial levels . 4 The global mean temperature is currently rising at a rate of 0.2 ° C per decade because of previous and continued emissions ; the past decade has seen eight out of 10 of the hottest years on record . 4 , 5 These changes are primarily being driven by fossil fuel combustion . 6 Global warming causing climatic variability is predicted to cause more frequent heatwaves , bushfires , droughts , severe storms / flooding , rising sea levels , water shortages and loss of biodiversity . 6
Australia continues to break temperature records , the number
of ‘ hot days ’ we experience ( mean
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temperature more than 30 ° C ) is predicted to increase , as is the intensity and frequency of heatwaves . 7 The increase in heat is a leading source of climate-change-related health risk in Australia . 7 The 2019 / 2020 summer was devastating and unprecedented , with the hottest ever-recorded day nationwide , warmest December , second-warmest
summer , numerous high temperature records , dangerous fire weather conditions and the highest December accumulated Forest Fire Danger Index on record . 8
Climate change has several adverse health effects including ( but not limited to ): illness related to extreme weather events and air pollution ; reduced food availability and quality ; vector-borne diseases ; mental illness ; and occupational health impacts . 2 Vulnerable populations , such as those with pre-existing medical conditions like cardiovascular disease ( CVD ), the elderly , children , and the socioeconomically disadvantaged will suffer disproportionately . 9
This How to Treat discusses
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how climate change , through its association with extreme weather events , and air pollution , increase cardiovascular ( CV ) mortality and morbidity . It also explores how GPs can manage patients acutely , the cardiac benefits of climate change mitigation and measures to reduce personal carbon footprints .
TEMPERATURE AND CVD
GLOBAL extreme temperature events , both high and low , are more frequent .
Temperature and all-cause and CV mortality have a V or U shaped relationship , with extremes of both high and low temperatures increasing CV mortality and morbidity worldwide . 10-15 A 2017 meta-analysis found CV mortality risk increased by 5 % with extreme cold exposure and 1.3 % with extreme heat . 16 Higher CVD mortality is more closely associated with adverse temperatures in winter compared with summer , and with
17 , 18 increasing age .
Extreme high temperatures cause
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acute or immediate increases in mortality ( within a few days ) while extremely low temperatures cause delayed effects . 19
An Australian study found a V shaped relationship between mean temperature and CV deaths , with a 3.5 % increase in CV mortality with heat exposure occurring within 0-1
day , and a 2.8 % increase in CV mortality with cold exposure occurring at a lag of 10-15 days . 20
Populations in warmer regions tend to be most vulnerable to cold and those in cold climates are most sensitive to heat . Heat effects ( such as increased mortality ) are greater for colder cities , while inhabitants of hotter cities are more affected by colder
19 , 21-23 temperatures . Temperature variability ( which can be intraday / diurnal or interday ), has been associated with increased all-cause and CVD / coronary heart disease ( CHD ) mortality , hospital admissions for CVD , ischaemic heart disease ( IHD ), heart failure , arrhythmia
and ischaemic stroke . 24-28
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