Air purification in classrooms | Opening the window, the only solution?

Matthew Perrolt
Press

Focus on ultraviolet light

The Montreal company has sold SanuVox ultraviolet (UV) air purifiers to hundreds of schools in British Columbia and thousands in Ontario, according to its founder Normand Bryce. Last year, Quebec parents wanted to fund the purchase of Sanovox UV purifiers for their children’s schools, but faced rejection from school authorities.

Instead of saying CO detectors, we want the Quebec government to agree that we should not keep purifiers because they are too expensive₂ The problem will be solved, “said the engineer, a former professor at Polytechnic Montreal.

For the middle class, 100 m², Two Sanuvox units with a capacity of 300 cu.³ Per minute according to Mr. Bryce. On the Internet, sites report prices ranging from $ 1,500 to $ 2,000 for these models. The order of magnitude confirmed by Bryce. This means that the installation and replacement of UV bulbs can cost more than $ 3,000 per class, rather than lasting a few years. By comparison, the budget of CO detectors₂ 75 million for 90,000 units, including installation, or more than $ 800 per class.

Purification by these two Sanovox devices corresponds to three classroom air changes per hour. In a paper published last winter, the University of Toronto recommended six wind changes per hour instead.

In addition to the inconvenience, according to Mr. Bryce, opening windows in winter is very expensive in terms of heating. “Since the two oil shocks of the 1970s, there has been a lot of emphasis on energy efficiency,” Mr Bryce said. This led to buildings with much less ventilation than before. ⁇

Boil the drops

Another Montreal company, Hypertech, claims to have developed a prototype purifier using another technology called Hyperion. It costs only $ 500 per class. “There are no installation costs – you just plug the device into a normal power outlet – no maintenance costs, no bulbs to replace,” said Andr లా Lamarre, vice president of hypertech.

He specializes in hypertech technology, cloud computing and cybersecurity, working extensively with Ontario’s telemedicine program, making it one of the most advanced in Canada before the epidemic. Its hyperemia is being verified in an American laboratory. Hypertech is also working with Canadian and US technical and government agencies for certifications.

How does it work? The electric field in Hyperion‌ “boils down the airborne droplets of viruses and bacteria,” Lamarre said. UV rays, on the other hand, convert viral proteins. Mr. According to Lamarre, Hyperion technology is another technology, similar to ionization, but unlike the latter, it does not produce ozone. Ionization works by creating charged cells in which virus cells cling, but due to this creation of ozone it cannot be used on a large scale.

Approximately “35 wind changes per hour”

The third technology, low-wavelength UV, is currently being used in some buildings in the United States and is being tested in some retirement homes in Nova Scotia. David Brenner, a radio physicist at Columbia University in New York, one of the most intriguing researchers in the field, said the middle class spends US $ 1,000 to clean their air, regardless of the changes that followed. “With a wavelength of less than 235 nanometers (nm), UV is not harmful to cells in the skin and eyes, so you do not have to put light bulbs in airtight boxes,” Mr. Brenner said. Makes them possible to achieve.

Mr. Kenneth Rockwood is a geriatrician at the University of Dalhousie and a nursing home. Brenner was responsible for testing light bulbs and chose this technique with his son Michael Rockwood, an electronic engineer. “It costs a lot less than conventional UV purification devices that use 254 nm,” he said.^R Rockwood. The clinical trial will cost a total of 1.8 million and will be completed by the spring of 2023.

The American Conference of Government Industrial Hygienists, the authorities responsible for formulating health standards, put together a seven-fold increase in UV exposure to 222 nm. This is Mr. According to Brenner, it fits eight hours under the lamps he designed.

Mr. of Sanovox. Bryce believes it has the potential to create short-wavelength UV ozone. Mr. Brenner is not it, but D^R Rockwood is still considering placing ozone detectors in rooms where UV-222 nm bulbs are installed, as ozone can irritate the lungs.