Indoor Pollution: Is Montréal Facing a Silent Public Health Crisis? (2026 Investigation)

An invisible threat inside our Montréal homes: what the latest data reveals about indoor air quality

At AirGreen, we service homes throughout Montréal, Laval, Longueuil, the North Shore, and the South Shore every week to diagnose, correct, and prevent indoor air quality problems. And since the end of 2025, one worrying trend has become clear: indoor pollution levels recorded in several residential neighborhoods are now exceeding Health Canada’s recommended limits.

This exclusive investigation conducted by our field team is based on over 200 audits performed for clients requesting ventilation system inspections or quotes for air exchangers. What we discovered deserves urgent attention.

Worrying pollutant concentrations inside Montréal homes

Measurements taken in several Montréal boroughs — including Rosemont, Côte-des-Neiges, Outremont, and Villeray — revealed abnormally high levels of:

• CO₂: frequently above 1,200 ppm, especially in bedrooms

• PM2.5 (fine particles): up to 40 µg/m³ in poorly ventilated homes

• VOCs (volatile organic compounds): consistently detected in recently renovated dwellings

These numbers are well above Health Canada’s recommendations, which set the comfort threshold at < 1,000 ppm for CO₂ and < 5 µg/m³ for PM2.5 on an annual average.

Direct health effects: fatigue, migraines, accelerated aging

The impacts of this invisible pollution are very real:

• Chronic fatigue and recurring headaches

• Respiratory issues, even in non-smokers

• Worsening of symptoms in asthmatic or allergic individuals

• Accelerated cellular aging linked to oxidative stress

In several cases observed, installing a heat recovery ventilator (HRV) cut pollutant concentrations by half within just 48 hours of implementation.

Case study: intervention in Montréal-Nord in a townhome built in 2012

Mrs. G., a mother of two, reported her children having sleep disturbances, constant fatigue, and recurring odors in the playroom. Our diagnosis revealed:

• A CO₂ level exceeding 1,800 ppm at night

• Blocked ducts in the exhaust system

• An old air exchanger that hadn’t worked in years

Our solution:

• Full replacement with a Venmar EVO5 700 HRV air exchanger, programmable and quiet

• Complete duct cleaning

• Airflow balancing between exhaust and intake throughout the home

The results: CO₂ stabilized at 700 ppm, humidity regulated at 45%, odors eliminated, and the children’s sleep quality fully restored.

Montréal: a housing stock poorly adapted to modern ventilation needs

Part of the issue lies in Montréal’s aging residential building stock. Many homes and buildings were constructed before mechanical ventilation became code. Even newer constructions, while very airtight, often lack adequate air renewal.

In the Sud-Ouest borough, we surveyed several condos where no air exchange system had been planned at the time of construction. The result: residents breathing stale air, especially in winter.

How do you know if your home is affected?

Here are the common signs of an air quality issue:

• Stale or heavy air in certain rooms

• Persistent odors even with regular airing

• Mold in corners or around windows

• Indoor allergies worse than outdoors

• Fatigue symptoms with no clear cause

Practical solutions provided by AirGreen

We provide tailored ventilation solutions throughout Greater Montréal, adapted to every type of home:

• Installation of HRV or ERV air exchangers (Venmar, Lifebreath, Lennox, etc.)

• Replacement of outdated equipment with quieter, energy-efficient models

• Professional duct cleaning

• Installation of HEPA or activated carbon filters to remove fine particles, allergens, and odors

• Airflow balancing across different home zones

All installations are certified and handled by specialized HVAC technicians, with a full post-installation follow-up included.

What you can do right now

1. Request a free inspection of your air exchanger or ventilation system

2. Replace your filters every 3 to 6 months

3. Ventilate main rooms daily, even in winter

4. Avoid chemical air fresheners, opt for natural air purifiers

5. Speak to our experts to determine the right system for your home

AirGreen, a key player in addressing this silent crisis

For several years now, AirGreen has become a leading name in HVAC installation and air exchanger systems in the Montréal metro area. Our expertise, built from hundreds of residential installations, allows us to act with precision, transparency, and speed.

We don’t sell miracle solutions. We provide technical, targeted interventions, based on real data and a deep understanding of each household’s needs.

Contact AirGreen today to evaluate the air quality in your Montréal home. A silent crisis can be solved — with the right tools and the right experts.