Indoor Air Quality: Factors That Affect It

The Main Factors That Shape the Air You Breathe

Indoor air quality depends on several interacting factors: volatile organic compounds (VOCs) released by paint, new furniture, cleaning products, and certain building materials; carbon dioxide (CO2) levels, which rise with occupancy and inadequate air exchange; relative humidity, which encourages mold and dust mite growth once it climbs above 60%; and insufficient ventilation, which prevents all these contaminants from being properly cleared out. In tightly sealed but poorly ventilated homes, common across Greater Montreal due to energy-efficiency standards, these pollutants can build up far faster than they would outdoors.

Other sources deserve particular attention: radon, a naturally occurring radioactive gas that can seep in through the foundation and accumulate in poorly ventilated basements; carbon monoxide from poorly maintained combustion appliances; and fine particulates from cooking, wood heating, or outdoor smoke that infiltrates through windows and ventilation systems.

Why Test Indoor Air Quality

Indoor air quality testing in Montreal objectively measures VOC, CO2, and fine particulate concentrations and, when needed, mold or radon levels, rather than relying solely on symptoms reported by occupants. Results are compared against recognized guidelines to flag out-of-range parameters and target the most effective fixes, whether that means adjusting ventilation, upgrading filtration, or addressing a specific contamination source directly.

The best time to run this kind of test depends on the concern at hand: a winter assessment, when windows stay closed and air exchange is minimal, often gives a more representative picture of the conditions occupants actually experience for most of the year.

The Impact on Health and Comfort

Poor indoor air quality commonly shows up as headaches, persistent fatigue, trouble concentrating, respiratory irritation, and worsened allergy or asthma symptoms. Since most Quebecers spend over 90% of their time indoors, especially during the long winter months, the cumulative effect of poor air quality can have meaningful long-term health impacts even when symptoms initially seem mild. Mold testing in Laval is often recommended alongside air quality testing when symptoms persist despite adequate ventilation.

Thresholds Worth Knowing

Recognized guidelines suggest keeping CO2 concentrations under roughly 1,000 ppm in occupied rooms, with higher levels linked to reduced concentration and a stale, stuffy feeling. For total VOCs, a general threshold of concern sits around 500 micrograms per cubic meter, though tolerance varies by the specific compound involved. These benchmarks make it possible to interpret a test report objectively rather than relying on a subjective impression of the air.

Improving the Air in Your Home

Several straightforward measures can meaningfully improve air quality: increasing air exchange through proper mechanical ventilation, maintaining heating and cooling systems regularly, reducing VOC sources by choosing low-emission materials and products, and controlling humidity with a dehumidifier in summer. These steps matter especially in recently renovated properties, where new materials can keep off-gassing for weeks or even months.

In new and recently renovated homes across Quebec, heat recovery ventilators (HRVs) or energy recovery ventilators (ERVs) are increasingly used to bring in fresh air without the heating-cost penalty of simply opening windows during the coldest months — a detail worth checking during a home inspection when air quality complaints come up alongside high heating bills.

A Factor Linked to Mold and Thermographic Inspection

Indoor air quality is closely tied to other aspects of a building: untreated fungal contamination, like what's described in our article on mold warning signs and health risks, directly degrades ambient air, while a thermographic inspection often reveals the air leaks and moisture zones feeding these problems before they become visible. Our team offers these services in Montreal, Laval, the South Shore, and as far as Sherbrooke, for a complete picture of your building's health.