You've probably noticed: as soon as the cold sets in in Montreal, something changes in your home. The air becomes dry and oppressive. Your throat stings in the morning. Your children cough more. And that suffocating feeling that appears as soon as you close the windows for the winter.
It's not your imagination. Indoor air really deteriorates during the Quebec winter.
The figures are striking: we spend around 90% of our time indoors during the cold months. And during these long, cooped-up periods, we breathe air that can be up to 5 times more polluted than the air outside. Humidity levels often drop below 30% in our heated homes - well below the recommended minimum of 40%.
In Montreal, with winters lasting six months and temperatures regularly plunging below -20°C, we live in hermetically sealed environments for much of the year. This unique climatic reality creates specific challenges for our indoor air quality.
At Vortex Air, we've been helping Montreal families breathe easier for over 10 years. We know these winter challenges intimately. In this guide, we'll explain why your indoor air deteriorates in winter, and more importantly, what you can do about it.
Understanding the phenomenon: why winter worsens indoor air quality
Montreal winters radically transform our homes. What was an airy, comfortable space in summer becomes a closed environment where the air stagnates for months on end.
Constant heating dries out the air. Your heating systems - whether electric, gas or wood-fired - raise the temperature, but the relative humidity drops dramatically. Warm air can hold more moisture, but when you heat cold, dry air, you get hot air that's even drier.
The windows remain closed from November to April. That's six months with no natural air renewal. Every person who breathes, every cooking activity, every cleaning product - all these add contaminants to a volume of air that renews itself very little.
Modern insulation is a double-edged sword. Our homes are becoming better and better insulated to save energy - which is great for the electricity bill. But this airtightness also traps pollutants inside. What used to be an advantage for your wallet becomes a disadvantage for your lungs.
Wood-burning remains popular in many Montreal neighborhoods, particularly in the east end. This combustion releases fine particles that infiltrate even neighboring homes when the smoke stagnates on cold, calm days.
Technical and climatic factors in Montreal
Fine particles PM2.5 reach average concentrations of around 15 µg/m³ during winter in Montreal. This is significantly higher than in other seasons. These microscopic particles come from heating, cooking and even outdoor traffic that infiltrates our homes.
In Montreal's east-end neighborhoods, where wood heating is more widespread, pollution levels can rise by 15% or more on cold winter evenings. When smoke from several fireplaces stagnates due to thermal inversion, the whole area breathes more polluted air.
Inadequate ventilation is at the heart of the problem. Many homes in Montreal, especially those built before 2012, lack adequate mechanical ventilation. They rely on natural air infiltration - which is minimal in winter when everything is caulked.
The building code changed in 2012, requiring air exchangers (HRVs) in new construction. But thousands of older homes don't have them. These homes accumulate stale air all winter without a system to renew it efficiently.
Indoor humidity under 30% turns your home into a desert. Your nasal mucous membranes dry out and become more vulnerable to infection. Dust and particles stay suspended longer in dry air. Viruses survive longer on surfaces when humidity is low.
Condensation around windows during the winter creates localized damp areas - perfect for mold growth. These molds release spores that then circulate throughout the house via your ventilation system.
Impact on health: allergies, asthma and vulnerability
Children under 5 are particularly sensitive. Their developing respiratory systems react more strongly to irritants. If your child has more colds in winter, or develops a persistent cough, indoor air quality is often a major cause.
Asthma sufferers see their symptoms worsen considerably. Dry air irritates the respiratory tract. Allergens such as dust mites and animal dander concentrate in stagnant air. Triggers multiply exactly when people spend the most time indoors.
Seniors and the immunocompromised are at greater risk. Their ability to fight respiratory infections is already compromised. Breathing contaminant-laden air for months on end further weakens their immune systems.
Indoor humidity under 30% increases respiratory tract irritation measurably. Your nasal mucous membranes dry out, sometimes bleeding. Your throat becomes irritated. Your eyes sting. These are all signs that your air is too dry.
Recurring headaches, chronic fatigue and difficulty concentrating can all be linked to poor indoor air quality. These vague symptoms, often attributed to the «winter blues», sometimes have a very real and reparable cause.
Book a free air quality diagnosis in Montreal. At Vortex Air, we come to you, assess your specific situation, and give you honest recommendations. You deserve to know what your family is breathing.
Myths vs. reality: what you really need to know
There's a lot of confusion about indoor air quality in winter. Let's find out what's real and what's not.
Experts tell us the truth
TRUTH: An air exchanger (HRV) reduces 40% contaminants
Studies show that mechanical ventilation with heat recovery significantly reduces concentrations of indoor pollutants. A well-maintained HRV renews your air while recovering up to 85% of heat - so you can breathe easier without freezing or paying a fortune for heating.
The Institut national de santé publique du Québec (INSPQ) recommends mechanical ventilation as the main strategy for maintaining good indoor air quality, particularly in our modern, well-insulated homes.
TRUTH: HRVs have been mandatory in new construction in Montréal since 2012
The Quebec building code has required mechanical ventilation systems in all new homes since 2012. This is official recognition that our homes have become too airtight to rely on natural ventilation alone.
If you live in a house built before 2012, you probably don't have an HRV. It's an investment you should seriously consider for your winter health.
TRUTH: Indoor air can be 2 to 5 times more polluted than outdoor air
Health Canada and the U.S. Environmental Protection Agency (EPA) confirm this disturbing fact. In winter, when houses are closed, this difference often reaches the top of this range. You think you're protecting yourself from the cold by staying indoors, but you're potentially exposing yourself to more pollution.
TRUTH: Regular duct cleaning significantly improves air quality
Clean ducts allow better air circulation and reduce the recirculation of dust, allergens and contaminants. This is particularly important in winter, when your system is in constant operation and you depend entirely on recirculated air.
Debunking common myths
MYTH: «Electric heating produces clean air».»
False. Electric heating dries out the air and forces the recirculation of already contaminated indoor air. True, it doesn't produce combustion, but that doesn't mean your air is pure. All the contaminants already present - dust, allergens, VOCs from furniture and cleaning products - continue to circulate.
MYTH: «Just open the windows for 5 minutes a day».»
Not good enough. Five minutes of ventilation a day renews barely a fraction of the air in your home. For adequate renewal, you'd need to open your windows for several hours - which is impractical (and expensive to heat) when it's -20°C outside.
MYTH: «If I change my filters regularly, my air is good».»
Standard furnace filters capture coarse dust, but let through fine PM2.5 particles and most allergens. And they do nothing for VOCs or excess CO2. Changing your filters is important, but it's only part of the solution.
MYTH: «Indoor air is always healthier than outdoor air in winter».»
Completely false. Even in smoggy weather, indoor air can be worse if your home lacks ventilation. You accumulate contaminants day after day without adequate renewal.
MYTH: «Houseplants purify the air sufficiently».»
Plants help marginally, but you'd need dozens of plants per room to have a measurable impact on air quality. It's a nice addition, not a solution.
Download our free guide «Improving your IAQ this winter». A practical PDF with actionable tips, a seasonal checklist and explanations of ventilation technologies. Free, in French, and directly applicable to Montreal reality.
Practical solutions to improve the air in your Montreal home this winter
Enough about the problems. Here's what you can do.
Technological interventions and regular maintenance
Install an air exchanger (HRV) if you don't have one
Approximately 70% of new homes in Montreal are now equipped with an HRV. If your home dates from before 2012 and you don't have one, this is the most impactful investment you can make.
An HRV continuously renews your indoor air while recovering heat from the outgoing air. You keep your home cool without losing heat. Installation costs range from 2,000 $ to 4,000 $, but the return on investment in health and energy savings is quickly felt.
Transition Énergétique Québec (TEQ) sometimes offers subsidies for the installation of energy-efficient ventilation systems. Check out the programs available - you could save significantly.
Use HEPA air purifiers in main rooms
A good HEPA purifier captures 99.97% of 0.3 micron particles. Place one in your bedroom and one in your living room - the spaces where you spend most of your time. Make sure the purifier's capacity matches the size of your room.
Change filters according to manufacturer's recommendations. A saturated filter becomes ineffective and may even release contaminants.
Keep humidity between 40% and 50%
Use a humidifier to compensate for the dryness caused by heating. A hygrometer (15-20 $ at any hardware store) lets you monitor humidity levels.
Caution: too much humidity (over 60%) encourages mold. Find the right balance. If you see excessive condensation on your windows, reduce humidification.
Change your furnace filters every 3 months in winter
When your system is running constantly, filters clog up more quickly. A saturated filter reduces your system's efficiency and can recirculate dust. Invest in MERV 11 or 13 filters for better capture of fine particles.
Have your ventilation system checked before winter
Fall preventive maintenance ensures that your system runs optimally during the critical months. A technician can detect airflow problems, duct leaks, or failed components before they cause problems.
The role of ventilation system maintenance (Vortex Air service)
Your ventilation ducts accumulate dust, allergens and contaminants over the years. In winter, when your system is running 24/7, these accumulations are continually dispersed into your air.
Professional duct cleaning removes these contaminants at source. At Vortex Air, we use the suction-pulse method with HEPA filtration. We loosen and vacuum everything that has accumulated in your system - dust, pet dander, debris, even mold if present.
Decontamination of your HVAC systems goes beyond simple cleaning. If mold or biological contamination is detected, Health Canada-approved disinfectants are applied to completely sanitize your system.
Maintenance of your air exchanger (HRV) is crucial. Filters must be cleaned or replaced regularly. The exchanger core must be inspected and cleaned annually. A poorly maintained HRV becomes inefficient and can even become a source of contamination.
Our INVC-certified technicians inspect your entire system with endoscopic cameras. You see exactly what we see. We explain the condition of your ducts, identify potential problems, and recommend only what's really necessary.
Ideal timing? Autumn, before the heating goes into full swing. You start the winter with a clean, efficient system that will distribute healthy air for the next six months.
Plan a complete service for your ducts and ventilation systems - get a free estimate. Call 514-214-7492 or visit vortexair.ca. We go anywhere in Greater Montreal, 7 days a week.
When to act Montreal's recommended winter calendar
The timing of your interventions makes all the difference between enduring winter and breathing comfortably.
Routine vs. emergency maintenance
Preventive maintenance: autumn (September-October)
It's the perfect time to:
- Have your ventilation ducts cleaned
- Have your HRV inspected and serviced
- Install new equipment if necessary
- Test your systems before they reach full capacity
Planning in autumn guarantees availability. Once winter sets in, everyone calls at the same time, and lead times get longer.
Regular maintenance: every 3 to 5 years
For duct cleaning, the general recommendation is every 3 to 5 years. However, there are situations where more frequent cleaning is warranted:
- Pets: every 2-3 years
- Allergies or asthma in the family: every 2-3 years
- Smoking in the home: every 2-3 years
- Excessive moisture or mold history: every 2-3 years
Urgent interventions: as soon as necessary
Act immediately if:
- You detect a musty smell in the supply air
- You see mold around the grilles
- Your family develops new or worsened respiratory symptoms
- You've had water damage or flooding (even minor)
- Your airflow decreases significantly
After a flood, even in winter, ductwork must be decontaminated within 48 hours. Water creates the perfect conditions for rapid mold growth, even in cold weather.
Montreal areas at higher risk this winter
Certain neighborhoods and housing types face particular challenges.
East-end Montreal and neighborhoods with widespread wood heating
Mercier-Hochelaga-Maisonneuve, Pointe-aux-Trembles and some parts of Anjou have higher concentrations of fine particles in winter. If you live in these areas, investing in a good HEPA purifier becomes even more important.
Ahuntsic, Rosemont, Villeray - older homes without HRVs
These neighborhoods have many homes built before 2012, often without adequate mechanical ventilation. Insulation has sometimes been improved over the years, making these homes tighter without adding ventilation. It's the perfect recipe for stale air.
Basements and ground-floor apartments throughout Montreal
Basements are naturally more humid and less well ventilated. In winter, when heating is on, relative humidity can vary dramatically between the basement and upper floors. Basement and semi-basement dwellings require special attention to ventilation and humidity control.
North Shore (Laval, Terrebonne, Mascouche) and South Shore (Longueuil, Brossard)
Suburbs often have newer homes with HRVs, but they are also often larger and require well-sized and well-maintained ventilation systems. A large house with an undersized or poorly maintained HRV is no better ventilated than a small house without an HRV.
Take advantage of our winter offer: inspection + cleaning at a special rate. Until December 31, 2025, we're offering a complete inspection + duct cleaning package at a special price. It's the perfect time to get your home ready to breathe easier all winter long.
FAQ - All you need to know about indoor air in winter in Montréal
Why does my apartment seem «stuffier» in Montreal winters?
This sensation comes from the combination of dry, stagnant air and high concentrations of CO2. When your home is hermetically sealed, the CO2 you exhale builds up. Combined with the dry air from heating and the lack of fresh air renewal, this creates that suffocating feeling. An HRV or even just opening a window for a few minutes can provide temporary relief.
What's the difference between air purification and mechanical ventilation?
Purification filters existing air to remove particles, but does not renew the air. Mechanical ventilation (HRV) exchanges stale air for fresh outside air while recovering heat. Ideally, you need both: ventilation to renew the air and dilute contaminants, and purification to capture fine particles. But if you have to choose, ventilation is more important.
Is installing an HRV enough to guarantee good indoor air?
A properly sized and maintained HRV will greatly improve your air quality, but it's not a complete magic bullet. You still need to: control pollution sources (cleaning products, cooking), maintain adequate humidity, change your filters regularly, and have your ducts cleaned periodically. HRV is the foundation, but indoor air quality requires a comprehensive approach.
My child has more allergies in winter: does indoor air have anything to do with it?
Most likely, yes. In winter, allergens such as dust mites and pet dander concentrate in stagnant indoor air. Dry air irritates nasal mucous membranes, making them more reactive. And your child spends 90% of his time indoors, continually exposed to these allergens. Improving your ventilation and controlling humidity can dramatically reduce symptoms.
How often should I have my air ducts inspected and cleaned?
Inspection can be done annually if you have risk factors (pets, allergies, humidity). A complete cleaning is recommended every 3 to 5 years for most homes. If it's your first time, or if you've never had your house cleaned since you bought it, do it as soon as possible - you'll be surprised at what's hidden inside.
How do I know if my apartment or house is a high-risk IAQ building in Montreal?
You're at high risk if: your home dates from before 2012 without HRV, you have pets, someone smokes inside or near doors, you use a lot of scented or cleaning products, your basement is damp, you've had water infiltration, or family members have allergies or asthma. If several of these factors apply, a professional inspection is strongly recommended.
Are there any grants or programs available in Montreal to improve IAQ?
Transition Énergétique Québec sometimes offers subsidies for the installation of energy-efficient ventilation systems. The City of Montreal also occasionally offers home improvement assistance programs. Check with your borough or visit the TEQ website. Programs change regularly, but financial assistance is often available for investments in energy efficiency and air quality.
What are the visible/invisible signs of an indoor air quality problem?
Visible signs: Excessive dust that returns quickly, mildew stains around windows or grilles, excessive condensation on windows, musty or musty smells.
Invisible signs: Increased allergy or asthma symptoms, persistent coughing especially in the morning, recurring headaches, chronic fatigue, eye and throat irritation, difficulty concentrating. These symptoms often improve when you leave the house - a strong indication that the problem is coming from within.
Why choose Vortex Air to improve your indoor air this winter in Montreal?
Montreal winters are tough enough. You deserve to breathe comfortably at home.
Local expertise in and around Montreal
We're not just a company that cleans ducts. We're Montrealers who intimately understand the challenges of our climate.
With over 10 years' combined experience, we've worked on every type of building: old houses in Rosemont without HRVs, new condos in Brossard with high-tech systems, bungalows in Laval, plexes on the Plateau. We know the problems specific to each type of construction.
We served over 500 satisfied customers in the Greater Montreal area. Families who just wanted to breathe easier, seniors who were tired of coughing all winter, parents worried about their asthmatic children.
Our service is bilingual - French and English - because that's what Montreal is all about. You're comfortable in the language of your choice.
We're available 24 hours a day, 7 days a week. Air quality problems don't wait until Monday morning. If you detect a suspicious odor on a Sunday evening, we respond.
Certifications & transparency
Our technicians are INVC (Institut National de Ventilation et de Climatisation) certified. We're also in the process of obtaining our NADCA certification. These certifications guarantee that we follow industry best practices and stay up to date with the latest techniques and standards.
Our process is completely transparent:
- Free inspection - We come to your home, inspect your pipes with our endoscopic cameras, and show you exactly what we see. You see the images in real time.
- Clear and detailed quotation - We'll tell you what you need and why. The price we give you includes everything - no hidden charges, no surprise extras.
- Professional work - We protect your floors and furniture, we use commercial-grade HEPA equipment, and we respect your home.
- Before-and-after photo report - You can see the concrete results. Clean ducts, a system that breathes better. Visual proof that your investment was worthwhile.
We guarantee our work. If you're not satisfied, we'll come back and fix it. Our local reputation depends on your satisfaction - we take that very seriously.
Testimonials & results
Caroline, Rosemont: «My 4-year-old son had asthma all winter long. We didn't know what to do. Vortex Air came to inspect our ducts - the camera showed years of buildup. After the cleaning, it was like a different house. My son went through his first winter without an asthma attack. I'd recommend Vortex Air to anyone.»
Michel, Laval: «Our house dates back to 1985, and we've never had an HRV. In winter, it was always stuffy. Mohamed from Vortex Air advised us on an HRV and cleaned our ducts at the same time. The difference is incredible. We breathe better, we sleep better, and our heating bill has even gone down. A1 service.»
Nathalie, Brossard: «I was afraid it was just a scam, but the free inspection convinced me. They showed me with the camera what was hiding in my ducts. Honest, professional, and the price was exactly what they said it would be. No surprises. Five stars.»
The results speak for themselves. Our customers report regularly:
- 30-50% reduction in allergy symptoms
- Better quality of sleep
- Less dust in the house
- Fresher-smelling air
- Reduced energy consumption
Call 514-214-7492 for an immediate free inspection. Or visit vortexair.ca to book online
