Through the air and across the Island: An up-close look at a CBC P.E.I. transmission tower
The CBC transmission tower in Churchill, P.E.I., is the largest one on the Island. We took a drone up to learn more about how radio waves and digital TV are transmitted through the air.
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National Post
2 hours ago
- National Post
How does a rockslide happen? 'The mountain that moves' was Canada's deadliest
A large rockslide in Banff National Park left up to 15 hikers injured Thursday, leading to one potential death and raising a series of questions about how and why the disaster occurred. Article content With officials still working on rescue and treatment of survivors, it will be some time until an investigation concludes why the rockslide happened. But a look at published research and archive news articles on rockslides provides some general information about the dangerous occurrences. Article content Article content Article content Article content A rockslide happens when a large chunk of rock detaches itself from the mountain where it sits and begins sliding down the slope. Why does this occur? Well, natural erosion or seismic activity can cause a rockslide, as can heavy rainfalls. Human activity such as excavation, construction or mining can also lead to a rockslide. Article content As one chunk of rock begins its downward slide, it can quickly gain momentum and trigger massive amounts of other rock to also begin sliding, leading to devastating effects. notes a landslide or rockslide can occur 'when gravitational and other types of shear stresses within a slope exceed the shear strength (resistance to shearing) of the materials that form the slope.' Article content What's the difference between a landslide and a rockslide? Article content A landslide occurs when sediment or loose dirt disengages from a hill or mountain and begins moving downwards. A rockslide, however, means solid rocks are also being swept down a slope during a similar type of event. Rockslides are also incredibly fast-moving, as they tend to move down a flat surface of a mountain. Article content The most horrific rockslide in Canadian history occurred in 1903 when a huge slab of Turtle Mountain crashed down onto the town of Frank and Crowsnest Pass (about 250 kilometres southwest of Calgary). At least 72 known residents were killed in the natural disaster, as were an undetermined number of others visiting or passing through the area. Some historians thus put the death toll closer to 90. Article content An estimated 80 to 110 million tonnes of rock were involved in the deadly event that came to be known as Frank Slide. The rockslide only lasted about a minute and a half. Article content Newspaper clippings and archive stories from the rockslide describe the horrific results that led to the deaths of men, women and children. As those clippings note, information about the state of some of the victims was disturbing, but shed light on how powerful the rockslide was: 'The leg and hip of a man was found lying fifty yards from the Imperial Hotel.'
CBC
5 hours ago
- CBC
Through the air and across the Island: An up-close look at a CBC P.E.I. transmission tower
The CBC transmission tower in Churchill, P.E.I., is the largest one on the Island. We took a drone up to learn more about how radio waves and digital TV are transmitted through the air.
CBC
6 hours ago
- CBC
Tire particles, perfumes, metals? Extensive study of Toronto air looks at what we're breathing in
What's contributing to Toronto's air pollution? 1 hour ago Duration 1:59 Walking down Fort York Boulevard on a fresh, breezy afternoon, scientist Elisabeth Galarneau has no issue pointing out possible sources of air pollution. The manicured lawns and flower beds? A potential source of airborne pesticides. The nearby high-rise apartment buildings? A source of pollutants from both heating and cooling, not to mention the cleaners and personal care products being used inside — remnants of which could be circulating down at street level. Charcoal barbecues, restaurant stoves, fire pits, squealing tires, nearby highways? They all contribute to the air Torontonians breathe. Now, the first glimpse at an in-depth study conducted by Galarneau and over 100 other scientists looking at winter air quality in Toronto is shedding light on rarely-measured air pollutants across the city, such as microplastics, brake wear chemicals, and metals. "We've done this study to kind of look at the whole mixture of what people are exposed to in cities, as well as how that varies from neighbourhood to neighbourhood," said Garlarneau, who works for Environment and Climate Change Canada. Researchers 'didn't expect' to see AQHI exceeded As the principal investigator on the Study of Winter Air Pollution in Toronto, known by the acronym SWAPIT, Galarneau led a group, that included contributors from 11 universities, that collected air samples from across the city over six weeks from January to March 2024. Winter is a "typically understudied part of the year" that's known for having cleaner air than the smoggy summers, Galarneau said — making the early results of their work all the more surprising. "We thought we would see low concentrations" of pollutants, said Galarneau. Instead, they clocked a number of instances of pollutants heading into moderate or high risk levels on the Air Quality Health Index (AQHI). "That air quality health index, I didn't expect to see it exceeded in the winter," she said. Another surprise? The degree of variation in air pollution depending on neighbourhood. Monitoring sites were placed across Toronto, from Pearson Airport in the west, York University to the north, and University of Toronto Scarborough in the east. One site was even perched on the CN Tower, 275 metres in the air. "Some pollutants are quite uniform across the city," Galarneau said. "But other ones are sometimes 40 times higher than the average depending where you're looking." The specifics of where air pollution is worse — and by what degree — will be revealed in the next year or so, when the study's peer-reviewed results are published in full. Looking for patterns To prepare for that publication, Galarneau and her colleagues will now begin a large-scale piece of detective work: determining where the pollutants are coming from, the health impacts for the people breathing them in, and the ways in which factors like income affect exposure. "The data set that we're producing here is going to help us to maybe see some patterns here in Toronto, and then expand that to other cities in Canada," she said. That forthcoming analysis on health impacts has drawn the attention of Jeffrey Brook, an assistant professor at the University of Toronto's Dalla Lana School of Public Health, whose work on air pollution is cited by SWAPIT researchers. "How can it be that in places like Canada where generally our [transportation emission] levels are considered some of the lowest in the world, we can continue to see health effects?" he said. "That's a big mystery, not just for Canada, but for the world." Over in Mississauga, environmental activist Rahul Mehta also looks forward to seeing SWAPIT's results laid out in full. Mehta, who heads up an organization called Sustainable Mississauga, says poor air quality impacts him both at work, where he encourages newcomers to try active transportation, and personally, as he deals with allergies and mild asthma. "Knowing these risks … I think that's going to help us, it's going to protect us and it's going to then maybe empower us to demand some better regulations from government," he said. Toronto Public Health, which is a partner on the SWAPIT study, said that its results promise to be useful for exactly that reason, telling CBC Toronto in an email that the study outcomes will "provide valuable evidence to guide local policies and actions."
