COVID-19 and beyond: impact of air pollution

HEALTH authorities and the government must be congratulated on the rapid response to the coronavirus disease 2019 (COVID-19) pandemic, preventing many more deaths in Australia as a result.

Risk factors identified for increased fatality are related to an ageing population, especially to the elderly over 70 years of age, comorbidities and/or co-infection, overcrowded living, overwhelmed health systems, or if people avoided adequate health care.

We also recognised that certain populations other than the elderly are at increased risk of harm from COVID-19 and at increased risk of mortality. These include people with chronic diseases such as diabetes, hypertension, heart and lung disease, obesity and overweight, and people who are immunocompromised and those who have cancer. Aboriginal and Torres Strait Islanders over 50 years of age are also a high risk group.

Smoking has been identified as a risk factor for increased mortality associated with COVID-19. Recent research suggests smokers are more vulnerable to infection and may have a higher risk of serious illness from COVID-19.

So, like smoking, can air pollution create similar effects on the lining of the respiratory tract increasing the risk from COVID-19?

Air pollution

A positive outcome to the lockdown that many people noticed was the air was considerably cleaner worldwide. There was a marked reduction in air pollution and emission levels due to less industry operating and fewer vehicles on the roads. More people were exercising outdoors as our air quality measurements improved; the streets were quieter and safer. Despite the many difficulties we faced during the pandemic, this has been a welcome positive change that we must learn from.

Air pollution was a hot topic during the summer’s bushfires (here and here), leading to increased morbidity and mortality. In recent times, it has also gained much media focus since the publication of several studies that found it may be associated with increased risk of mortality in patients with COVID-19. For example, data from a national study from Harvard University of approximately 3000 counties in the US found that small increments of only 1 μg/m³ in long term exposure to particulate matter less than 2.5 μm in diameter (PM_2.5) was associated with an 8% increase in the COVID-19 death rate. Another analysis of COVID-19-related deaths based in Europe found long term exposure of high levels of nitrogen dioxide (NO₂) — a pollutant emitted by vehicles — was associated with increased fatality caused by COVID-19. Similar reports and analyses of data found a trend of higher incidence of morbidity and mortality, with mortality rates up to 12% in areas of high pollution in parts of northern Italy compared with approximately 4.5% in the rest of the country. Sources of PM_2.5 and NO₂ include fossil fuel combustion from motor vehicle exhaust, industry and coal-fired power stations.

In general, air pollution is a known risk factor for a number of diseases and is associated with increased risk of mortality and chronic diseases, such as heart and lung disease, and can increase the risk of lung infections, pneumonia and hospitalisations even from exposure at low doses below current national standards. For example, short term exposure to air pollutant PM_2.5 leads to increases in health care use due to lower respiratory tract infections in children and adults in urban environments. Air pollution can increase the risk of inflammation of the lungs, making them more susceptible to harm to diseases such as COVID-19.

More research is required to validate if air pollution is a contributor to increased risk of infection and mortality. There are likely to be other confounding factors contributing to these findings also.

Lessons learned from the COVID-19 pandemic

We have learned many lessons from this pandemic, and we will likely be better prepared for any future pandemics. Clearly, improved lifestyle choices such as avoiding smoking, reducing obesity, and increasing appropriate sun exposure to help address risk factors of infections are major key public health messages.

Whether air pollution is or isn’t a significant modifiable contributor to mortality associated with COVID-19 deaths, the studies and the improvement of air quality during the pandemic do remind us why we should continue to urgently further research, tackle and tighten air pollution standards in Australia and the rest of the world. The pandemic gave us a welcoming glimpse of breathing clean air, making exercise outdoors safer. Many studies have demonstrated exposure to air pollution can lead to a number of adverse health effects, including susceptibility to infections, respiratory and cardiovascular disease, which may subsequently increase vulnerability to COVID-19.

What next?

After the pandemic, will we return to the way things were or will we learn more about our relationship with our planet? What public health messages learned during the COVID-19 pandemic can we provide our community, for example, during the influenza season? What prevention strategies can we use to help educate the community about adaptation responses to infections and pandemics in the future?

In 2019, peak medical bodies called on authorities to strengthen air pollution standards in Australia as air pollution is a modifiable risk factor for increased morbidity and mortality. In line with international studies, Australian research shows there is no safe level of air pollutants even well below the threshold standards. Consultation has now closed, but the decision for the tightening of air pollution standards is likely to occur in the very near future. Australia’s current population in 2020 is about 25.43 million people. It is projected to reach 30 million people by 2033. As our population grows, air pollution from more vehicles on the roads and consequent emissions will be a constant challenge to us all. The pressure on the federal government to tighten air standards should continue so we can achieve cleaner air as we experienced during the COVID-19 pandemic.

The challenge will be after COVID-19 restrictions are lifted, with the return of air pollution from emissions such as vehicle and industry and the ongoing health impacts it will have on humans.

Associate Professor Vicki Kotsirilos AM is a Melbourne GP, and a member of Doctors of Environment Australia.

 

The statements or opinions expressed in this article reflect the views of the authors and do not represent the official policy of the AMA, the MJA or InSight+ unless so stated.