Science-y Stuff

Air Quality Class is in session.

Air Quality

High quality air filters keep your indoor air clean and free of harmful particulate matter, like virus carriers or toxins.

Air Filters

There are a lot of options. Second Nature makes sure you have exactly what you need when you need them.


This scale rates the efficacy of an air filter when it comes to filtering the air—it ranges from 1–16.


Regular air filter replacements can reduce your energy bill by up to 15%. Plus, it helps prevent costly HVAC repairs.

Air Quality 101

Poor air quality has a big impact on the health of you and your home. Letting it get worse can lead to some serious complications.

Indoor Air Pollution

When you think “air pollution,” what comes to mind? The foggy smog over LA? Pollen clouds coating southern skies in sickly pale yellow? Outdoor air pollution is a real concern, sure, but the air inside your home can be up to 5x worse.1 Yeah. Air circulation isn’t what it used to be! Modern homes are built tighter to improve energy efficiency, which is great. Unfortunately, natural air doesn’t flow in, so the air in our home stays funky. So, you know, maybe crack open up a window or two from time to time.

Are you familiar with Sick Building Syndrome? Sounds made up, right? 100% real. The World Health Organization defines SBS as a “medical condition where people in a building suffer from symptoms of illness or feel unwell for no apparent reason.”2 WHO studies have linked “mucous membrane irritation (eye, nose, and throat irritation), neurotoxic effects (headaches, fatigue, and irritability), asthma and asthma-like symptoms (chest tightness and wheezing), skin dryness and irritation, gastrointestinal complaints” and more as a few symptoms to SBS. That’s about as real as it gets right there.

Indoor Air Quality

IAQ is quite the buzzword these days. The EPA defines it as “the air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants.”3 It’s not a full-on red alert public health issue, but when you factor in poor outdoor air quality, it’s a bit more problematic. Outdoor air quality is measured by the EPA on the AQI, more on that here. AQI fluctuates, but even when it’s trending well, there’s a handful of nasty Volatile Organic Compounds ready to strike.

According to the EPA, VOCs “are emitted as gases from certain solids or liquids. VOCs include a variety of chemicals, some of which may have short- and long-term adverse health effects.”4 They are things like benzene or formaldehyde, and they hide in all sorts of things. Plenty of common paints contain aliphatic hydrocarbons, ethyl acetate, glycol ethers, acetone. Formaldehyde hydes (get it) in paint as well, but it’s also in ceiling tiles and adhesives. Benzene is a known carcinogen and is usually found in cigarette smoke and smoke from a wood burning fire. So if you’re painting, smoking, or adhesing (not a real word, but roll with us here), filter your air! Open a window, make sure you’re circulating the indoor air, and make sure you have a fresh air filter installed. Wink.

What’s the Best Air Filter?

Poor air quality has a big impact on the health of you and your home. Letting it get worse can lead to some serious complications.

Pleated (Second Nature) Fiberglass Washable
Cost $10 to $30 each Less than $5 $50+
Material Polyester or Cotton Paper Fiberglass Usually Aluminum
Replacement Frequency Every 30 to 90 Days Every 30 Days Never
Maintenance Level Easy: Replace Easy: Replace Hard: Requires Cleaning
Efficient at Catching
Large Debris
Efficient at Catching
Small Particles
Recommended for People
with Allergies
Pleated(Second Nature) Fiberglass Washable
$10 - $30 > $5 $50 +
Polyester or
Cotton Paper
Fiberglass Typically
30-90 Days
30 Days
Hard: Needs
Large Debris
Large Debris
Large Debris
Small Particles
Can Be Reused
Good for
People with
Allergies & Pets

How Are Air Filters Rated?

Air filters are graded on the MERV scale. MERV stands for Minimum Efficiency Reporting Value, a rating scale from 1 to 16. The higher the MERV rating, the more effective the filter will be at trapping airborne particles and toxins.

MERV Rating Particle Size Typically Seen In Controlled Contaminants
1–7 3–10 µm Low End Residential, Industrial Workplaces, Commercial Buildings Pollen, sanding dust, textile fibers, carpet fibers, paint overspray.
8 (Essential) 3–10 µm Better Residential Everything above and mold, spores, dusting aids, cement dust.
10 (Essential+) 1–3 µm Superior Residential Everything above and large bacteria, pet dander, smaller dust particles, and auto emissions.
13 (Health Shield) 0.3–1 µm Superior Residential Everything above and some bacteria, cooking oil smoke, smog, some tobacco smoke, and droplet nuclei (sneeze).
14–16 <0.3 µm Smoking lounges, hospital inpatient care, general surgery. All bacteria and most tobacco smoke.

Higher MERV ratings put more strain on your HVAC system, and most homes don’t need anything beyond a MERV 13. Our filters hit the sweet spot of MERV 8, 10, and 13, keeping your home filtered well without expensive energy bills.

Filter Benefits

Air filters are brilliant. Unpopular opinion? Maybe. Do we stand by it? Absolutely. Here’s why: regularly changing your air filters means you’ll use less energy. Your HVAC unit loves it when it doesn’t have to suck air through a mess of particle junk, so it won’t run longer to keep your house at the optimal temperature. The less it pushes itself, the less likely it is to breakdown! That saves you money on costly repairs. With all that money you save you might be able to take that much needed vacation! Or at least treat yourself to a spa day.

Changing your filters also means the air in your home is cleaner and healthier for you and anyone else under your roof! MERV 11 filters can actually reduce the risk of infections from droplet nuclei by 60% (MERV 13–16, that number’s up to 64%). What are ‘droplet nuclei,’ you ask? Great question. You know when someone’s sick or sneezing all the time? They aren’t blasting out air alone; there’s all sorts of nastiness flying around. That nastiness? Droplet nuclei. Still glad you asked?

So change those filters, people! We don’t want to hear “I’m too busy” as an excuse, either. With Second Nature, we’ve made it as convenient as possible for you. Simply sign up, select your filter size and quantity, choose your quality level, and schedule your deliveries. Every shipment reminds you to change your filters, and that is undeniably brilliant.

What’s the Best Filter for My Home?

We offer three different filters, rated MERV 8, 10, and 13. Essential (MERV 8) is the entry level filter. It gets the job done better than a cheap fiberglass filter, and you can swap it every 3 months. The next step up is our Essential+ (MERV 10) filter. If you have pets or allergies, this one’s a must. Finally, we have the Health Shield(MERV 13) filter. This one’s great if you, or someone in your home, suffer from other respiratory conditions. It filters out some of the smallest particles like cooking oil smoke or cigarette smoke.

“Useful” Air Filtration Information

You know, when it comes to air filters, there’s a surprising amount of information to absorb. We kinda love this stuff, but we know not everyone cares! You’re still reading, though… so maybe you’re just as weird as we are? That’s good, we like weird. Here’s some more weird info for you, weirdo.

Familiar with the term pressure drop? This is a metric that measures the impacts different air filters have on your home’s air flow. A filter is typically installed in a return to intercept the air intake going to your HVAC system. Too high of a pressure drop and your HVAC unit will overwork itself. That’s no good. Using a pleated filter increases the surface area, giving you a low pressure drop while still hitting good MERV ratings. ‘Good’ being anything MERV 8 or higher. Anything under a MERV 8 is worthless, unless you enjoy breathing old sneeze particles and litter box dust.

Another term comin’ atcha: arrestance. This measures the ability of an air filter to remove synthetic dust from the air. We want our filters to arrest any sort of unnatural gunk that doesn’t belong in our lungs. The HVAC wizards of ASHRAE test arrestance with a specific kind of dust. It’s a magical mixture of 72% “Arizona Road Dust,” 23% powdered carbon, and 5% cotton linters (fibers used in paper making). Magnificent.

Ever heard the term brownian motion? It’s the random, zig-zaggy motion of particles in suspension, like in a liquid or a gas. This happens when there’s a thing with a… thing - you know what? That’s too much science, even for us. If you wanna learn more, head to Wikipedia or a phriendly neighborhood physicist. Ooh! But what about agglomeration? That’s a fun sounding word! This is when airborne particles collide and create larger particles.

While we’re at it, here’s one more for you: Van der Waal force, named for Johannes Diderik van der Waals, are the forces of attraction between molecules. He was Dutch, won the Nobel Prize in Physics in 1910, and had a sweet beard. If you think about it, beards are kinda like air filters for your face. They catch all sorts of particles. Too gross? Probably too gross.

Let's Wrap This Up

However did you find the time to read this far? Oh, so silly of us, you must be using Second Nature to automate the delivery of your air filters every couple of months! You’re welcome for that free time back, although we really think you oughta read something a tad more interesting, how about this, this, or this?

Have any questions for us? Think we didn’t cover enough? Think we covered too much? Whatever you might need, we’re here to help. If you’re super into reading all the scientific information about air filters but you haven’t given us a shot, why not try today? Clearly you appreciate the fine art of air filtration.