The Science of Indoor Air Quality & How to Improve it
Your home air is 2–5x more polluted than outdoor air. Here's what actually works to fix it — and the two air purifiers I actually use.
Ultra fine particles contribute to poor indoor air quality.
Have you gotten home from a week away and noticed your house smelled musty? I consider myself a clean freak so its a small identity crisis when I get home and I think my house smells old.
Your house should actually smell like nothing. Not air fresheners, or clean laundry, or especially lavender scented Clorox.
That musty smell led me to find a small mold instance around some of the air vents. A consult with an HVAC mold specialist recommended lower quality HVAC filters and higher quality air purifiers
You’re one small upgrade away from drastically improving it
According to the EPA, your home air traps 2 to 5 times more pollutants than outdoor air.
Best pick for 99% particle removal.
We think our HVAC filters are doing the heavy lifting, but most standard residential systems can’t handle the added load of a high performance filter.
This is where air purifiers come in. Using HEPA technology they trap and remove tiny particles in the air. This includes common allergens, mold spores, dust, even smoke and some VOCs.
HEPA is the base standard but some filters provide Ulta HEPA filtration for an even cleaner experience, I’ve included the two units I’ve bought and would recommend below.
My favorite unit is the AirDoctor 3500, but it comes at a pretty high price point. It captures 99.99% of airborne particles at 0.003 microns, which is 100x smaller than the HEPA standard. It’s a higher price point, but after the mold scare it was worth it to me.
Best budget purifier pick
We have a second house that we rent on AirBnb. When I bought a preventative filter for that house, I went with the GermGaurdian XL. I’ve used smaller models from them and find they strike a balance between effectiveness and cost. It’s about half the price of the AirDoctor.
The GermGaurdian uses HEPA technology instead of the higher effective UltraHEPA. It still traps 97% of airborne particles but can’t get some of the smaller particles the AirDoctor can capture.
Both units auto sense and will ramp up filtration when they detect more airborne particles than normal. It’s humbling to see what activities cause the filters to ramp up. Blow drying my hair, spray deodorant, and candles all trigger it go into overdrive
What are the contributing factors to indoor pollution
Building materials, smoking, cooking, and biological contaminants like dust and mold all pollute your indoor air. Worse yet, traditional cleaning methods backfire. Weekly use of store-bought cleaners increases your risk of lung disease. Air fresheners trigger asthma attacks. And don't overlook radon, a leading cause of lung cancer in the United States, even though it contributes less to day-to-day air quality issues.
The National Institute of Health (NIH) includes the below visual to demonstrate the many sources of indoor pollution.
Illustration from the NIH showing the various factors that contribute to indoor pollution.
Why indoors is worse than outdoors
Modern builders construct new homes to strict energy efficiency standards, sealing them airtight to minimize heating and cooling costs. They deliberately eliminate air leaks and gaps throughout the structure. This saves you money on energy bills but traps pollutants inside. Builders choose synthetic materials to cut costs without realizing these products slowly release chemicals into your home for years. Berkeley and Harvard researchers revealed these dangers in the late 70s and early 80s, yet builders still haven't adopted the science. Consumer demand is starting to change some of these practices. As with everything it takes time for the word to spread. But if you’re reading this you still have plenty of time to make changes and start improving your home’s air quality.
How it impacts your family’s health
Radon and carbon monoxide slowly poison us. This is easy to prevent, make sure you have CO2 detectors and get occasional radon tests!
Certain bacteria and mold trigger pneumonia and infections, hitting young children and elderly family members hardest. Indoor air fresheners, scented cleaners and candles trigger or worsen asthma attacks. Seems scary, but again this is highly preventable with an air purifier. You don’t need to make big changes to limit your family’s risk/
Women face a greater risk. We spend more time cooking, cleaning, and at home so our exposure is higher. Our homes should offer our families a safe space to recharge and rest. Instead, they threaten our health with higher concentrations of chemicals.
What to do next
Remember to change your filters.
You can improve your indoor air quality in three ways: control sources, ventilate better, and purify the air. Start by controlling the chemicals you bring home. Choose safer cleaning products and ditch artificial fragrances. Next, open windows for just 15 minutes daily and run exhaust fans while cooking or showering to flush out stale air.
Finally, invest in a true HEPA filter and change your HVAC filters regularly to clean the air that circulates through your home. I can promise they made a noticeable difference in my own home. There’s so many factors we can’t control for our families but this is an easy one and adds lasting value.
This post contains affiliate links. However, the recommendations are my own paid purchases and were not gifted.
45% of US Tap Water Contains PFAS. Here's How to Protect Your Family
The U.S. Geological Survey found that almost half of all tap water tested contains PFAS or "forever chemicals." You've ditched non-stick pans for cast iron, but what about the water flowing from your faucets?
Your water may look and taste fine but still harbor invisible contaminants.
If you don’t filter your drinking water its time to start.
Switching to filtered water takes almost no effort and could meaningfully lower exposure to chemicals and microplastics.
I started to question my exposure to environmental toxins when my 4 year old dog developed a mast cell tumor even though she was eating a fresh food diet. It may seem dramatic, but pets and children react to much smaller levels of chemical exposure.
They’re an early warning sign that we have opportunities to improve our home’s health. When you know better you do better.
Why U.S. Tap Water Isn't as Safe as You Think
The U.S. Geological Survey found that almost half of all tap water tested contains PFAS or "forever chemicals." You've ditched non-stick pans for cast iron, but what about the water flowing from your faucets?
Your water may look and taste fine but still harbor invisible contaminants. Pollution enters at the source, during treatment, or through your home's pipes. Old infrastructure and regulations allow for harmful chemicals into our drinking water.
Keep reading to understand what causes the problem, but I think everyone should use some sort of water filtration. Skip to the end for my preferred options.
EPA regulations can’t keep up with chemicals in circulation today.
Aging Infrastructure
Builders constructed many water systems 50-100+ years ago. Metro areas have even older systems—some homeowners still have lead, wood, or terracotta pipes.
9 million service lines still contain lead. Flint wasn't isolated.
Outdated Regulations
Congress enacted the Safe Drinking Water Act in 1974, but regulations haven't kept pace. The EPA regulates roughly 90 contaminants, yet 300,000+ chemicals are in use today.
"Legal limits" don't always equal "safe limits."
This is why some consumers prefer to use EU brands. The EU is a more risk averse system where brands must prove ingredients are safe. The US allows brands to self certify ingredients are safe and tend to assume ingredients are safe until proven otherwise.
What's Hiding in Your Tap Water
There’s a myriad of things in our tap water. Some are harmless and some are a little more suspect.
There’s more contaminants in your water than you think.
PFAS ("Forever Chemicals")
Linked to cancer, thyroid disease, immune problems
Microplastics
220,000 to 1.2 million particles enter your body annually through tap water
PVC pipes degrade and release these particles
Lead
Corrodes from old pipes and fixtures into your water
Fluoride
2 million people receive water above safe thresholds
This one is still being hotly debated and lacks consensus from the scientific community
Pesticides & Nitrates
162 pesticides detected from source to tap
Agricultural runoff contaminates groundwater
Pharmaceuticals
Treatment plants can't filter them completely
Endocrine disruptors (think thyroid and fertility impacts) affect hormones (proven in fish, concerning for humans)
Chlorine Byproducts
Disinfection kills harmful microbes but creates new risks
Why testing isn’t worth the money.
You can test your water through the EPA’s Consume Confidence Report or use independent testing.
The EPA only tests for regulated contaminants (the 90, not the 300,000+). They also use levels that not everyone agrees are safe.
Labs like Tap Score provide comprehensive testing for $100-300. However, most filtration options are less than $300. You’re better off spending your money on a solution, not understanding how big the problem is.
Remember odds are your water could be better. I’d skip the test and just get a filter.
Water Filtration: What Actually Works
Understanding filtration is confusing. Few filters address all concerns. Here's the breakdown:
Time to upgrade from that Brita pitcher.
Pitcher Filters (Brita, PUR)
Water trickles through inexpensive activated carbon. Removes chlorine taste, but that's about it.
Gravity Filters (Berkey, Waterdrop King Tank)
Gravity forces water through millions of microscopic pores that trap contaminants.
Under-Sink Filters (Hydroviv)
Blend activated carbon, catalytic carbon, and ion exchange resins. Physically and chemically remove contaminants.
Reverse Osmosis Systems
The gold standard. Forces water through a semi-permeable membrane with microscopic pores. Blocks 99.9% of contaminants—lead, PFAS, arsenic, bacteria, viruses, pharmaceuticals, microplastics.
Given the potential health hazards, the conservative approach makes sense. Countertop RO systems offer affordability. Under-sink systems provide convenience with larger clean water tanks.
Water quality matters most for developing bodies. If you're pregnant, trying to conceive, or raising small children, invest in reverse osmosis. Better to be more conservative here.
There’s a filter option for every budget and situation. Anything is better than tap water.
Let’s control what we can. Especially when its so simple.
Small changes create big health impacts. Start today and rest assured you’re on the path to making your family healthier and happier. I’ve used all of these products at various points in my filtration journey.
Whatever you choose, make sure you understand filter cost and frequency of changes. Some of the upfront cheaper units need monthly filter changes. That adds up quick!
→ Shop My Top Water Filter Picks:
Best No Plumbing Option: Countertop RO Filter – Comprehensive protection without installation. Remineralization is a must or you’ll have to buy drops to add to the water.
Best Overall: Waterdrop Under-Sink RO System – Integrated solution with large clean water capacity
Best for Renters: Waterdrop Gravity Filter – No plumbing required, excellent filtration
A Note on Water Access
We're fortunate to consider whether our tap water is healthy enough. An estimated 2.2 million Americans lack running water entirely. Consider supporting organizations like the Navajo Water Project that bring clean water to communities without this basic necessity.