Your Air Quality is Killing You. How to Fix it.

Everything I've learned about indoor air quality with devices and actionable tips.

Table of Contents

Your air quality is likely killing you.

And making you dumber.

Why air quality matters and how to fix it...


Indoor air quality is often horrible.

Sealed homes and small offices build up CO2 and trap harmful chemicals.

Cognitive impairment is common.

And you don't always notice the impairment.


CO2 has similar effects to being sleep-deprived.

You'll feel off / tired, or you may not notice.

Cognition drops linearly with CO2 and quickly.

15% lower with moderate CO2 (~ 945 ppm)

50% lower with CO2 concentrations of ~1,400 ppm, pretty common in a small room.

CO2 Levels

500 CO2 is great. Only happens outdoors or with a window open.

1,000 CO2 is common indoors. Start feeling tired.

1,500+ CO2 can happen quickly indoors without open windows. Office, gym, coffee shop, etc. Not good.


Above 65% relative humidity, you have conditions for mold to grow.

Mold is up there with formaldehyde as bad for your health.

Formaldehyde poisoning is pretty rare. Mold poisoning is pretty common.

Black marks on bathroom caulking are the first place you'll see it.

What's Ideal Air

• Temperature: 68-72F (64-66F for sleeping)

• Humidity: 40-60% RH

• CO2: <600ppm

• VOC: <300ppb

• PM2.5: <10ug/m3

Too hot rooms wreck your sleep quality.

How to Measure

Awair Element

My favorite for home. Best app and trends. I have a few throughout the house.

It tracks CO2 as well as toxic chemicals and particulate matter.

Not portable though. Needs wifi and plugs into the wall.


My travel one. Super accurate CO2 with long battery life and e-ink screen. I don't love the design, but it is super small and easy to toss in a backpack to monitor on the go.

Qingping Air Monitor Lite

Cheaper popular one. Looks nice.

How to Fix

CO2 - Bring in fresh air. Open windows when possible. I run the HVAC fan often to disrupt CO2 pockets as well. Filters don't help with CO2.

Particles - Higher quality air filters. I use MERV-11. Room air purifiers work.

Humidity - HVAC should take care of it.


Indoor plants look great and make you happy but do close to nothing to improve air quality.

A person releases about 1kg of CO2 per day.

An indoor plant absorbs less than 1kg of CO2 per year.

You'd need to fill your entire home with plants to equal opening a window.

This talk by DHH is great for more background on why air quality matters.

TLDR on Indoor Air Quality

- Bring in fresh air

- Plants don't work

- CO2 fogs your thinking

- Measure to find issues

- Buy higher-quality filters