Since the start of the COVID-19 outbreak, a connection between air pollution and COVID-19 severity had been suspected but not proven. In the first study of its kind, a group of scientists at Harvard’s T.H. Chan School of Public Health have found concrete proof that air pollution exposure worsens COVID-19 mortality in a dramatic way.
What Did the Harvard Study Look At?
The early study focused on 3,080 different counties in the United States, and set out to explore links between air pollution trends over the last 15-17 years, and COVID-19 outcomes across different areas.
The only pollutant they focused on in this study was fine particulate matter - PM2.5. These particles are very small, at up to 2 and a half microns in width - for context, this could be about thirty times smaller than that of human hair. PM2.5 comes from a wide range of sources, including power plants, vehicles, residential wood burning, forest fires and natural dust.
What Did The Study Find?
The study found that long-term exposure to Fine Particulate Matter was significantly linked to COVID-19 likelihood of death. In other words, those living in highly polluted areas were significantly more at risk of dying from the deadly disease. Specifically, the researchers found that a one unit increase (1μg/m3) in long-term average exposure to fine particulate matter was associated with a 8% increase in COVID-19 mortality rate on average.
The correlation was so strong that just a slight increase in particulate matter levels would have worsened outcomes. The scientists stated:
If Manhattan had “lowered its average particulate matter level by just a single unit of one microgram per cubic meter, over the past 20 years, the borough would most likely have seen 248 fewer COVID-19 deaths by this point in the outbreak”.
What Surprised the Scientists?
The devastating impact of air pollution for human health is already well known. The World Health Organization states that an estimated 4.2 million deaths are linked to air pollution exposure - mainly as a result of heart disease, stroke, COPD, lung cancer and acute respiratory infections.
However, the strength of the association found in this study between COVID-19 mortality and PM2.5 is almost 20 times higher than the association of PM2.5 and all-cause mortality, which is 0.7%.
Image source: Maps show (a) county level 17-year long-term average of PM2.5 concentrations (2000-2016) in the US in ug/m3 and (b) county level number of COVID-19 deaths per one million population in the US up to and including April 4, 2020.
Dr Francesca Dominici, the author and Director of Data Science at Harvard’s T.H. Chan School of Public Health said she was initially ‘surprised’ at how strong the association they found was but she later realized it made total sense:
“This is like adding gasoline to the fire. People that have been breathing polluted air for a long time, we know that long-term exposure to fine particulate matter increases inflammation in the lungs and potentially in the cardiovascular system. If on top of that, these individuals are affected by COVID-19, then it’s not surprising given that they’ve already been impacted by fine particulate matter, that they might respond with much worse health outcomes than someone who lives in a clean air county”
What Does this Mean?
This groundbreaking study underlines why it is more important now than ever to manage our individual air pollution exposure. The scientists involved hope their findings will help bring more of a focus on air quality for public health policy, both in the future and when it comes to tackling the current COVID-19 outbreak. They have illustrated here that the longer we wait, the more people’s health is put at risk. This means there is an urgency to act now, the devastating health impact of air pollution exposure can not be ignored.
“In states where we haven’t yet seen higher numbers of deaths, we need to pay attention because they are at higher risk of much worse health outcomes for COVID.” - Dr Francesca Dominici,
Dominici also stated that weakening official air quality standards was an ‘irresponsible decision’.
More research is needed to correlate the impact of air pollution exposure, specific population groups and COVID-19 severity. It is not clear how much factors such as age, race and socioeconomic status also impact the air pollution and COVID-19 correlation. Another next stage would be to assess the impact of exposure to other pollutants asides from particulate matter.
How BreezoMeter is Helping
For further actionable conclusions, additional research is also needed using air quality data at a much smaller spatial resolution than was used in the initial study, at the zip code level rather than county level. As BreezoMeter offers the highest resolution air quality information in the world at 5 meters, we’ve decided to open our data up for free to any research group looking to explore these links in more detail. Research is more important than anything else right now!
Additional Research of Note
Air Pollution Could Help Transmit COVID-19
Coronavirus has recently been detected on particles of air pollution by a group of Italian researchers; scientists are now investigating the possibility that air pollution itself contributes to COVID-19 spread, increasing the overall numbers of people infected. The work is in preliminary stages but the team involved in the study believe this theory could help to explain the higher rates of infection in parts of Northern Italy. Learn more here.
High Levels of Nitrogen Dioxide Linked to Higher COVID-19 Deaths
A European based study focused on 66 administrative regions in Italy, Spain, France and Germany found that 78% of COVID-19 deaths occurred in just five regions, which were also the most historically polluted. The research focused on historical levels of No2 exposure, suggesting prolonged exposure to this pollutant could also contribute to Coronavirus mortality. Learn more here.