If you’re a homeowner in Canada, you’ve probably thought about your indoor air quality—especially with our ever-changing weather bringing everything from dust to allergens into our homes. One of the easiest ways to improve the air you breathe is by choosing the right furnace filter. But with all the different options out there, how do you know which one is best? That’s where MERV ratings come in.
MERV, or Minimum Efficiency Reporting Value, is a rating system that tells you how effective an air filter is at trapping airborne particles. The higher the MERV rating, the better the filter is at catching small contaminants like dust, pollen, pet dander, and even bacteria. But in 2025, with newer technology and air purification options available, do MERV ratings still matter? Let’s break it down and see why they’re still an important part of keeping your home’s air clean and healthy.
What is a MERV Rating?
The MERV rating system was developed by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) to evaluate the effectiveness of air filters in trapping airborne particles. The ratings range from 1 to 16, with higher numbers indicating a greater ability to capture smaller particles. Filters with higher MERV ratings can trap finer particles, including dust, pollen, mould spores, pet dander, and even bacteria. Some scales include even higher ratings when engineered to filter smaller particles than the guidelines define.
A breakdown of the MERV ratings
- Ratings between 1-4: Filters labelled with these ratings are usually the least expensive and also the least effective. These filters are disposable and can capture pollen, dust mites, cockroach debris, sanding dust, spray paint dust, textile fibres, and carpet fibres. These filters may help your home comfort system, but they do not help you.
- Ratings between 5-8: These filters are pleated and offer greater performance in capturing smaller particles such as mould, spores, dust mite debris, cat and dog dander, and hair spray. Helpful to your system still but less so for human health.
- Ratings between 9-12: Filters that are labelled with these ratings are also pleated and produce even greater results in improving indoor air quality. Allergy sufferers will greatly benefit from the decreased exposure to pollens and other allergens.
- Ratings between 13-16: Filters that are labelled with these ratings provide excellent indoor air quality and capture up to 95% of the particles and pollutants in the air. Although these air filters cost more than other air filters, they are highly effective. Please note that some residential HVAC units may not be compatible with this rating.
Less particles lead to cleaner air and higher HVAC efficiency. In the long run, you’ll also save money and energy knowing that your air filter is performing at its maximum capacity.
Choosing the Right MERV Rating for Your Home
Selecting the appropriate MERV rating depends on several factors:
- Health Considerations: If household members suffer from allergies, asthma, or other respiratory conditions, filters with a MERV rating between 9 and 12 can significantly improve indoor air quality by capturing smaller particles that may trigger symptoms.
- HVAC System Compatibility: While higher MERV-rated filters offer superior filtration, they can also restrict airflow if the HVAC system isn’t designed to handle them. This restriction can lead to increased energy consumption and potential system strain. It’s essential to consult with an HVAC professional to ensure your system can accommodate higher-rated filters without compromising performance.
- Environmental Factors: Homes located in areas with high pollution levels, frequent wildfires, or significant construction activities may benefit from higher MERV-rated filters to combat increased airborne contaminants.
Maintaining Your Furnace Filter
Regardless of the MERV rating, regular maintenance of your furnace filter is crucial:
- Replacement Frequency: Standard 1-inch filters should be replaced every 90 days. However, households with pets, smokers, or individuals with allergies may need to replace filters more frequently, approximately every 30 to 60 days.
- System Usage: During peak heating or cooling seasons, when the HVAC system is in constant use, consider checking and replacing filters more often to maintain optimal air quality and system efficiency.
MERV Ratings in 2025: Are They Still Relevant?
As of 2025, MERV ratings remain a standard metric for assessing air filter performance. However, advancements in air filtration technology have introduced new products that offer enhanced capabilities.
For instance, smart air filters now monitor air quality in real-time and adjust filtration levels accordingly. These innovations provide more dynamic responses to indoor air quality challenges, but MERV ratings continue to serve as a foundational guideline for filter selection.
Summary: MERV Ratings and Their Capabilities
Understanding the capabilities of different MERV ratings can help homeowners make informed decisions:
| MERV Rating | Particle Size Efficiency (in microns) | Common Contaminants Filtered | Suitable Applications |
| 1-4 | 3.0 – 10.0 (<20% efficiency) | Pollen, dust mites, textile fibres | Residential settings with minimal filtration needs |
| 5-8 | 3.0 – 10.0 (20% – 70% efficiency) | Mould spores, pet dander, hair spray, cement dust | Standard residential and commercial environments |
| 9-12 | 1.0 – 3.0 (50% – 85% efficiency) | Legionella (bacteria), lead dust, auto emissions, welding emissions | Superior residential and better commercial spaces |
| 13-16 | 0.3 – 1.0 (50% – 95% efficiency) | Bacteria, tobacco smoke, sneeze droplets, some viruses | Hospitals, general surgery, inpatient care |
| 17-20* | < 0.3 | Viruses, all combustion smoke, carbon dust | Cleanrooms, radioactive & carcinogenic materials, pharmaceutical manufacturing |
*Not part of ASHRAE’S MERV Ratings (Standard 52.2)
Breathe Easier with the Right Furnace Filter Today
MERV ratings still matter in 2025, and choosing the right furnace filter can make a big difference in your home’s air quality.
Not sure which MERV rating is best for your home? The experts at Air Treatment ClimateCare are here to help! Contact us today to breathe easier tomorrow!
