Cooler weather can play havoc with indoor air quality
by Lisa Wichmann
TORONTO—The scorching heat of summer leads to windows and shipping doors flung wide. But what happens when the cooler weather approaches? Without precautions, the season could bring ill employees, malfunctioning machinery and ebbing productivity.
“If the ventilation system has been deficient in any way, the problems don’t typically show up in the summer because they open bay doors,” said Mike Shaw, senior project manager with the emissions reduction and compliance group of consulting firm Pinchin Environmental Ltd. (Toronto).
Without the additional air from summer breezes, imbalances and defects in the ventilation, air make-up and supply systems quickly become apparent.
“A lot of industrial environments tend to operate under negative pressure because supply air needs to be conditioned or heated in the winter. Sometimes, companies take shortcuts and they put in a lot of exhaust, but they really don’t want to put in that tempered air supply because it’s a very significant operating cost,” Shaw said.
The situation can cause safety equipment such as fume hoods and capture systems to become air-starved and lose performance.
“What you see a lot in the metalworking industries is blue haze from welding or cutting fluids,” he said. “It’s actually a very fine particulate.”
Hazards more difficult to spot are volatile organic compounds from coatings, paints, printing chemicals and solvents, which can result in headaches and even vomiting in quantities surpassing occupational exposure limits, he added.
Another problem? The right equipment—in the wrong place. Shaw has noticed air supply systems creating cross drafts; and exhaust systems positioned too far away from operations due to obstacles such as cranes and hoists.
He’s also seen negligent maintenance and inspection of fans, dust collectors and thermal oxidizers—all leading to potential discomfort, and on the more serious end, illnesses.
“Absenteeism can be the result…If you’re not providing a reasonably comfortable environment then productivity is going to drop off and will affect morale as well.”
Whose responsibility is it?
That’s not to say manufacturers should become HVAC experts, but they have to take the lead with inspections and safety planning, added Christopher Liddy, occupational health and safety specialist with the Canadian Centre for Occupational Health & Safety (Hamilton).
“They have an obligation to take every reasonable precaution to ensure the safety of workers…and to follow up if there’s a complaint…inspect the HVAC system or have a competent person inspect it and ensure it’s maintained. Sometimes they will need professional expertise, whether it be an engineer or a maintenance company but there are things they can do themselves, such as training, identifying issues and knowing how to follow up.”
Staff can be trained to spot problems such as standing water, he said—a big culprit in the growth of mold, and illnesses such as Legionnaire’s Disease. Groups of employees with the same complaint—such as nausea or itchy eyes—should also raise a flag for supervisors.
Despite the tendency of some manufacturers to depend on drafts from doors and windows, Liddy says it’s ill advised.
“Having windows and doors opened or closed shouldn’t be the mechanism they rely on for safety,” he says. “There are standards in place for various industries that set a minimum for mechanical ventilation.”
When considering air quality, manufacturers are often guided by their jurisdiction’s occupational exposure limits (OELs). Even with good compliance though, air-related issues can arise.
“They [OELs] are not necessarily going to protect every person,” said Donald Weekes, president of the Indoor Air Quality Association and partner with InAIR Environmental Ltd. in Ottawa.
“You’re going to have people that react to much lower levels…In some cases they may have a susceptibility to it because of their past exposure…Are you going to add respirators or some sort of ventilation, or are you going to do rotation of work? So plans have to be made that go beyond the regulations in that regard.”
Depending on the problem, equipment such as blowers or make-up systems might be required, to avoid pockets of low air supply in the plant, he said.
Neighbours can also be an issue at this time of year. Smaller shops in shared facilities may get complaints from nearby offices over chemical odours or fumes.
“It falls down onto the responsibility of the shop owner to make sure whatever they’re doing in that shop is not going to affect their neighbours or themselves. The ventilation is probably designed as one size fits all but of course it doesn’t,” Weekes said.
“Dedicated ventilation units may have to be installed to make sure [operations] are properly filtered and vented to the outside.”
He also advises manufacturers to watch the weather, to avoid turning on the heat too soon. Cranking up the heating system without anticipating a late warm spell could lead to thermal discomfort and overheated machinery, he added.
Good air quality can be a complex issue to tackle, but diligent inspection, maintenance and planning go a long way to heading off problems.
Useful info: CCOHS OSH answers: Indoor Air Quality
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