top of page

Canadian Wildfires Pose Health Risk: MERV vs HEPA filters, what to use.

Please be aware that we do not manufacture, fix, or install units or filters. Nor are we climatologists, firefighters, or involved in fire-safety. Any and all health recommendations are purely based on science as breathing practices we use. Use this guide to make informed decisions for you, your home, and your loved ones and please reference sources.

Over 3.7 million hectares of Canadian wildfires are burning, posing a big health risk for many Americans. Here's how you can protect your lungs, your family, and your home with this guide between MERV 13 & HEPA filters; which is better and when to use.

MERV vs HEPA: protect your lungs from wildfire haze.

What is causing the Canadian wildfires?

The Canadian border, only 3 hours north of New York, separates the United State of America from some of the densest forest in the world. Although no one really thinks about it (especially if you're from Texas), every year Canada experiences an annual wildfire season typically ranging from May through October.

On average, the majority of these fires are caused by lighting strikes in densely wooded areas. However, this year has been exceptionally bad with 3.7+ million hectares (as of 6.7.23) already burned. Normally these wildfires would pose a minimal risk to the United States and neighboring areas, but with the 423 active fires, and 246 of them out of control, New York (as of 6.7.23) now ranks #1 for lowest air quality in the world.

What causes "haze" and why is it dangerous?

Haze is a cloudy, smoky look to the air. It describes a situation where the air becomes filled with tiny particles (smaller than 0.3 microns) that give it the appearance of "fog" or "smoke". These particles can come from pollution, wildfires, or even dust in the air.

Haze, although not dangerous for most people at small doses, can become dangerous when we breathe in these particles for a prolonged period of time, or at a high enough concentration. In this case haze can cause lung problems making it hard to breathe.

Those who have lung disease, asthma, or any other breathing disorder are at an increased risk of developing breathing related issues if exposed to haze. Therefore it is important to be cautious and try to avoid areas with heavy haze, and/or stay indoors when possible.

MERV filter vs. HEPA filter

Iso-Aire breakdown of particle size capture per filter type

What is a MERV filter?

MERV stands for "minimum efficiency reporting value". A filter can be MERV rated if it passes specific criteria on filtration as set by the American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE).

As seen in the chart above, a MERV13 filter can trap up to 75% of particles sizes 0.3-1.0 microns. A standard home box filter may be rated at MERV 9-11, which may only capture less than 20% of particulates smaller than 0.3 microns.

The big units you see on top of a commercial building and are called HVAC units. Although very good at keeping a 20,000 sq/ft building cool in the 100+ degrees heat of Austin, Texas, they only take a MERV 16 filter at best, leaving a lot of particulates still circulating inside.

What is a HEPA filter?

HEPA stands for "high efficiency particulate air". HEPA is the leading standard of peak filtration, as it far exceeds the capture rate of a MERV filter.

Referencing the chart above, anything above a MERV 17 filter will capture 99.97% of particulate matter smaller than 0.3 microns. Being as haze can often have particulars smaller than 0.3 microns, a MERV 17+ filter is the ideal solution.

Note: A MERV rating of 13-16 is considered hospital level air quality.​

What kind of filter should I use?

Although HEPA filtration is certainly ideal, there are limitations to consider. Without going into the rabbit hole of aerodynamics and turbulence, the finer the filter the more it will trap and the greater the air resistance is required for it to work properly.

Some companies like Iso-Aire manufacture units that can easily be upgraded from a MERV standard to a HEPA filter. However, most standard household units are limited to the MERV standard.

So, if you have a home and can upgrade your filter, a MERV 13 filter is the recommended and best choice to keep anyone in your home's lungs clear from pollutants.

According to Filter King this upgrade will cost roughly $30 per filter. That said, you may want to consider the common issues that can occur before jumping in.

Possible issues to upgrading to a MERV 13 filter:

  • Resistance to air flow

  • Increase of pressure in the duct system

  • Increase in energy used to power your HVAC system

  • Reduction of air flow

  • Freezing of the air conditioner coil

  • Damage to the compressor

  • Cracking of the heat exchanger

  • Put carbon monoxide into your home

  • Dehumidify better

Breathe better Naturally

Download our FREE Mindfulness Field Guide

Don't forget to follow us on social media.

If you found this post helpful and enjoyable,

please like, share, and save.

Improving Wellness Through Design

From daily planners, to workouts, and exercise apparel, we design wellness that works.



Rated 0 out of 5 stars.
No ratings yet

Add a rating
Jun 11, 2023
Rated 5 out of 5 stars.

Thanks for the content. Very educational and easy to read. 😊 I appreciate the updates on current events


Jun 10, 2023
Rated 1 out of 5 stars.

This isn't accurate information. Please check you facts about the numbers of acres burned. This is no where close. The inaccuracy of this information suggests that the products being advertised are also not worth their weight.

Ryan Brenner
Ryan Brenner
Jun 11, 2023
Replying to

We apologize for any misunderstanding in information. All information is cited and dated. For current up-to-date numbers on specific acreage please reference this link cited in the post:

bottom of page