Science·What on Earth?

Keeping a distance: How safe are running and cycling amid COVID-19 measures?

In this week's issue of our environment newsletter, we examine how close is too close when running or cycling during COVID-19 and what our response to the pandemic says about our ability to fight climate change.

Also: The potential for carbon farming in capturing emissions

(Sködt McNalty/CBC)

Hello, people! This is our weekly newsletter on all things environmental, where we highlight trends and solutions that are moving us to a more sustainable world. (Sign up here to get it in your inbox every Thursday.)

Note: Next Wednesday marks the 50th anniversary of Earth Day. Check out Earth Day Canada's website for tips on how to mark the occasion this year (#EarthDayatHome).

This week:

  • Keeping a distance: How safe are running and cycling amid COVID-19 measures?
  • Carbon farming: Putting soil to work to capture carbon
  • Is our response to the novel coronavirus indicative of our ability to fight climate change?

Keeping a distance: How safe are running and cycling amid COVID-19 measures?

(Sean Gallup/Getty Images)

Last week's article on the rise of cycling amid physical distancing measures generated some comments from readers who were worried, given the findings of a recent study by Dutch and Belgian engineers

The study, which hasn't yet been peer reviewed, did computer simulations of droplets coughed, sneezed or exhaled around someone walking quickly, jogging and cycling, based on wind tunnel measurements in a previous study.

It suggested people directly behind a runner or cyclist — but not beside — should leave extra space beyond the two-metre minimum recommended in physical distancing guidelines. That means 10 metres for a runner and even more for a cyclist.

However, in a Q & A on Medium, the researchers, Bert Blocken and Thierry Marchal, noted:

  • The study doesn't draw any conclusions on the infection risk associated with particular distances or droplet exposure.

  • People shouldn't stop exercising outside, as that's important for mental and physical health.

In an interview about the study on CBC's Toronto radio show Metro Morning on Tuesday, Dr. John Presvelos, a physician with the sports medicine clinic Athlete's Care who was not involved in the study, said the physics seemed interesting. 

But does it mean the droplets shown in the study's graphics could cause infection?

"I personally don't think so," Presvelos said, noting that particles tend to be more dispersed outside and subject to humidity, wind currents and temperatures that might hinder transmission. 

Even so, he said, "Personally, I'd be more inclined to leave a larger amount of distance — 10 metres, if possible."

Linsey Marr, an expert in airborne transmission of viral diseases and a professor of civil engineering at Virginia Tech, told WIRED magazine that it's still not known whether people can become infected from cyclists and runners. The magazine noted that so far, there are no published studies of person-to-person spread of COVID-19 outdoors.

Emmanuel Stamatakis, a professor of physical activity, lifestyle and population health at the University of Sydney, wrote in The Conversation on Wednesday that it would be "irresponsible" to give advice to the public about exercise outdoors "based on a computer simulation that has not been checked for even its theoretical scientific rigour."

Stamatakis noted that maintaining a five- to 20-metre distance when walking, running or cycling outdoors would make it almost impossible to exercise in some cities. It could discourage some people from going out at all and could "generate conflict and friction between people who think others are not heeding the advice to stay safe."

"Stick to official advice," Stamatakis said, "and do not rush to make any new lifestyle decisions."

— Emily Chung

Reader feedback

In light of physical distancing measures during the coronavirus pandemic, some stores have insisted on using plastic bags to carry groceries, insisting they are safer than reusable bags brought from home. Some of our readers are not convinced.

Joan Thompson writes, "It's interesting that some people (and governments) feel that reusable shopping bags can help spread COVID-19. I have stopped going to the one store I know which refused to let me put my groceries into my own bag and imposed a plastic bag on me. The others have no problem. The items are placed on the counter, charged and pushed to the other end, where the customer puts them in his/her bag. The cashier never touches the bag. It's true that the packers who work in big chains touch these bags, but perhaps we could think of the environment while trying to reduce contamination."

Roger Payne writes, "We are just putting our groceries back into the cart after checking through and taking them out to our car to bag them in our reusable bags. It makes going through the cashier line quicker and does not put you in a position of arguing with the cashier — which no one should be doing at this time."

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Old issues of What on Earth? are right here.

The Big Picture: Carbon farming

There has been a lot of talk in recent years about accelerating tree-planting initiatives around the world, given that trees are excellent at carbon storage. Less has been written about soil, which can also sequester carbon. But there are signs it's getting a closer look — for example, a fund led by U.S.-based commodities trader Cargill will pay American farmers to capture carbon in their field soil (and then sell those carbon credits to polluting companies and municipalities). A study published in October found that if farmers maximized the health of their soil, it could sequester as much as 4.5 gigatonnes of carbon worldwide every year. That's a lot, but to put that in context, it's still only a fraction of overall emissions, which reached 39 gigatonnes in 2019.


Hot and bothered: Provocative ideas from around the web

  • On April 22, 1970, millions of Americans took to the streets for the first Earth Day to raise awareness of the ways we are harming the environment. Since then, the campaign has met with resistance from companies that say that regulating toxic industrial practices is prohibitively costly. This article looks back at the legacy of Earth Day and shows that regulatory changes to everything from recycling to emissions reporting have not only improved health, but have also been good for jobs and the bottom line.
  • Reducing plastic pollution seems like an insurmountable challenge, but a French company has come up with a concept that could take a bite out of the problem. It's a mutant enzyme that digests old plastic bottles — within a few hours, in fact — and leaves the basic chemical ingredients to make new plastic. (The journal Nature recently did a study confirming that the process works.)
  • China's rise as an economic powerhouse is partly attributable to its massive agriculture sector. In the process of growing all that food, China has used a lot of fertilizer. The country has come to recognize the environmental harms of fertilizer (including soil contamination and algae blooms), and through a concerted effort to revise its cultivation practices, now ranks as a world leader in organic farming.
  • Oslo, Norway, has a construction site that is completely emissions-free. It includes a battery-powered electric excavator that can charge in an hour.

Is our response to COVID-19 indicative of our ability to fight climate change?

(David Mercado/Reuters)

Last week, business columnist Don Pittis wrote about what the slow response of most countries to the novel coronavirus has in common with action on climate change.

Now that the COVID-19 threat is upon us, scientists and innovators are pulling out the stops to find ways of coping. That rush of invention is no surprise to historians.

In the 1620s, living through the plague inspired economist and polymath William Petty to devise a system to count the cost of future calamity. Part of the "political arithmetic" he invented includes concepts we use today to try to imagine how much it's worth spending now to prevent something worse from happening several years down the road, said Canadian economist Aidan Vining.

Unfortunately, our failure to prepare for an outbreak that epidemiologists have repeatedly warned was coming is a reminder that humans are not very good at thinking themselves into the future.

Society's blinkered approach to the future risk of disease provides a lesson for our failure to address the potentially catastrophic effects of climate change. In fact, history shows that the people who do think ahead are often ridiculed.

Vining said that in the 1840s, one follower of Petty's cost-benefit analysis, Edwin Chadwick, was known as "the most hated man in England," for promoting public health spending that Chadwick insisted would save lives and improve living conditions for millions.

"Why? Because he wanted to build sewer systems, and the elite were so opposed because of the public spending it would involve," said Vining, professor emeritus at Simon Fraser University.

Chadwick lived to see his plans put in place, helping to lead a global public health movement that ultimately saved lives and money. But apart from people like Chadwick, behavioural economists have shown that even when we know we would benefit from worrying a bit more about our long-term future, humans are hard-wired for short-term thinking.

Economists have long noted our preference for having something now rather than later, which is one of the justifications for interest rates. You can have that car or house today, but it will cost you — in large monthly interest payments.

In economics, a calculation of something called the social discount rate is an attempt to apply interest rates to show how much it is worth spending today to prevent something horrible from happening in the future.

Canadian economist David Burgess said it's pretty clear no government in the world had invested enough in preparations for the current pandemic. Despite the lessons of SARS, we did not have stockpiles of essential equipment, and many governments had made tax-saving cuts to medical services.

Burgess said that while social discount rate analysis works for deciding how much governments should spend on things like roads or bridges, it may not be appropriate for problems like epidemics and climate change. That's because the future costs are so difficult to measure in dollar terms. He calls it "a big bag of uncertainty."

That hasn't stopped some economists from trying — in the case of climate change, by estimating various amounts for how much is worth spending now to prevent future economic fallout.

According to economist Carolyn Fischer, who works with the University of Ottawa's Smart Prosperity Institute, another difficulty is calculating the present value of the risk of planetary devastation. If a future plague could lead to complete societal and economic breakdown similar to what happened during the Black Death, Fischer said it may be worth spending a lot to prevent it from happening — even if we cannot be sure if or when it will occur.

Fischer said the same thing applies to climate change.

If science tells us that economic ruin is the eventual result, it may be the job of governments to compensate for our natural tendency to worry about the short term and ignore the future.

Said Fischer, "Maybe we can draw some lessons from this [crisis] for what happens when you react too late."

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Editor: Andre Mayer | Logo design: Sködt McNalty

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