Have you ever walked into a room and felt worse in a way you couldn't quite describe?
This would happen to me a lot. Some indoor spaces like my parent's house, some hotel rooms, and my own room in the Spring and Winter would leave me feeling tired, slow, anxious, sneezy, and irritable. I'd find an explanation for why I might be feeling that way in the moment but usually after a few minutes outside I'd go back to feeling great.
Feeling bad in some indoor spaces is called sick building syndrome but it can have many causes. After years of putting up with these vaguely bad feelings I started diving deep into what specific things might be causing my health problems and what I could do about it.
What I came to find out is that there are five categories of air quality that can make indoor air feel better or worse: temperature, PM2.5, humidity, CO2, and VOCs. Each of these can have a strong effect on how you feel and your ability to think. For a small amount of initial effort and money each one can be controlled to keep you healthy.
Here's what I did to make my indoor air as good for me as possible.
It's hard to improve something if you're not measuring it. I already had a few ways to measure indoor air temperature but it's harder to find ways to measure other important dimensions of air quality: PM2.5, humidity, CO2, and VOCs. I've been using an Awair Element but it looks like that company might be shutting down. I think the uHoo might be the best one to buy today. For something cheaper check out handheld air quality monitors.
For a really cheap option buy the raw electronic air sensor components and make your own air quality monitor with an Arduino. The advantage of making your own sensor is that it will make it easier down the road to make smart feedback systems.
This is the only dimension of air quality I was previously controlling. With the brief exception of a few months I spent living in Australia, I've lived my entire life with a central air conditioner heating and cooling the indoor spaces I've lived in.
Air that's too cold can make you sick and if it's very cold can kill you. Air that's too hot is uncomfortable and if it's very hot can kill you. Neither of these are problems I've seriously encountered in my modern life. because controlling temperature with an air conditioner is a solved problem. The only interesting thing to note here for later is that air conditioners also humidify the air.
PM2.5 (dust, dander, and pollen) #
Microscopic dust in the air can cause all kinds of negative health effects, including asthma, allergies, cold symptoms, and even heart problems.
This microscopic dust is called PM 2.5 which is short for "particulate matter 2.5 micrometers big."
Dusty air was the easiest part of my air quality to fix. I just needed an air filter, which is a fan attached to a fine mesh.
A cheap solution I used for a while was a simple box fan duct taped to a HEPA or MERV filter. I've since upgraded to a Molekule Air Mini+. The Molekule senses the amount of dust in the air and spins its fan faster the higher PM2.5 gets.
If you're building a house from scratch you can build a HEPA filter into your HVAC system.
Technically you only need to run a HEPA filter when there's dust in the air. If you don't mind spending a little extra on electricity just keep your filter on all the time.
In the Spring in Dallas running a HEPA filter in my bedroom helped aleviate my seasonal allergies by filtering out grass pollen from the air.
Just like temperature, humidity can be either too high or too low. If humidity is too high it can make it easier for mold to grow. High humidity makes a hot room feel extra hot and a cold room feel extra cold.
If humidity is too low it can dry out your nose, throat, eyes, lungs, and skin. When the air is dry it's easier for viruses and bacteria to stay in the air longer and pets tend to shed more, all of which can make you sick.
Unless you live in an especially hot and humid environment you probably don't have to worry about dehumidifying. Your air conditioner will take care of dehumidifying as it cools the air.
In the winter when you're heating your air it's very important to have a humidifier running as much as possible. Cold air can't hold as much water as hot air, so when cold dry air gets into your house and your air conditioner heats it up, it gets extra dry. This extra dry air is very good at sucking out moisture from your body.
A simple and cheap humidifier is a towel in a bucket of water with a fan running over it. You can also run the shower for a few minutes every hour. A more expensive a hassel-free humidifier is an evaporative humidifier, which is basically just a fancy towel in a bucket with a fan over it, but it's very effective and automatically turns off and on.
Ultrasonic humidifiers are alright too but usually have a very small capacity and need to use filtered water so they're not kicking up extra dust into the air from your dirty tap water. I learned most of what I know about humidifiers from this one technology connections YouTube video about them.
If you're building a house from scratch you can build a humidifier into your HVAC system.
I'd like to get my systems set up to the point that my humidifier automatically starts if the relative humidity gets below 40% and my dehumidifier starts if the relative humidity gets above 50%.
In the Winter running a whole-house evaporative humidifier fixed my itchy eyes, dry (and sometimes bloody) nose, and upper respiratory breathing problems that felt like allergies. Low humidity in hotel rooms (especially ones in Las Vegas) is a big part of why I used to get sick while traveling.
Your body breaths in oxygen (O2) and breaths out carbon dioxide (CO2). If you stop breathing you will die. If you breathe the same air over and over then all of the O2 in that air gets replaced with CO2 and you'll suffocate and die. The more air you're breathing the longer it will take to suffocate. In the room you're in right now you might be suffocating so slowly that you don't notice it.
I used to think that running my air conditioner was bringing in fresh air but air conditioners—even window units—just recirculate the air that's already inside. When all the windows and doors to a room are closed the only CO2 getting out is escaping underneath doors or through cracks in the wall.
It's easy to find yourself in a room with CO2 levels high enough to cause measurable cognitive impairment. Outside CO2 levels are about 500 parts per million (ppm). If you're in a poorly ventilated room the CO2 levels can slowly creep up to over 1,000ppm in just an hour or two. CO2 levels higher than 1,000ppm cause significant decreases in people's ability to think:
Keeping CO2 low is simple: just open a window. To keep CO2 extra low, open one window on each side of your indoor space.
If you want your indoor temperature, humidity, and PM2.5 to be different than what's outside then keeping CO2 low gets much more complicated.
I thought I might be able to keep CO2 low by having more indoor plants. That was a great idea but it's impractical. I'd need hundreds of plants per person to offset the CO2 significantly.
I also thought about how submarines must have figured out a way to keep CO2 low and O2 high in enclosed spaces. From a YouTube video called How Do Nuclear Submarines Make Oxygen?- Smarter Every Day 251 I got to learn how these systems work. Submarines use electrolysis on purified water to make O2 and H2. If O2 gets too low or if power fails the submarine crew can burn a candle made of Iron (Fe) and Sodium Chlorate (NaClO3) which liberates Oxygen. To scrub CO2 from the air submarines blow air through monoethanolamine (MEA) which absorbs CO2. The CO2-rich MEA can then dump it's CO2 into the ocean water.
The submarine solution to keeping CO2 low seemed unnecessarily involved for what I was trying to do. I have the advantage of being surrounded by high-O2 and low-CO2 air! What I needed to figure out was how to get fresh air in, filter it, warm or cool it, and then humidity or dehumidity it.
Filtering outdoor air is straight forward: just tape a HEPA filter to a window fan.
But how could I control the temperature and humidity? I chewed on this problem for months until I discovered a magical machine called an Energy Recovery Ventilator (ERV). An ERV takes in outdoor air through one side and indoor air through another rubs the two airstreams together in a box with hundreds of thin paper membranes. The thin paper membranes let the two airstreams exchange temperature and humidity.
In the summer in Texas the indoor air is typically around 75ºF and the outdoor air can be as hot as 110ºF and very humid. Outdoor air coming in through a window would be just as hot and humid as the raw outdoor air. Outdoor air coming in through an ERV would recover about 70% of its temperature and humidity so incoming outdoor air 35ºF hotter than indoor air would come in through an ERV only 10.5ºF hotter. An ERV works just as well in the winter when you want your indoor air to stay hot and moist.
I've only ever seen ERVs designed to be installed as part of an HVAC system but I figured out a way to install them in a room with a window. You'll need a piece of foam insulation, a few feet of insulated air ducts, and some duct tape. First cut the foam insulation to fit in your. Then cut holes in the foam for the ducts and tape them in the holes. Next tape the foam with the ducts in your window.
Finally connect the outdoor air input and output streams from the ERV to the ducts.
I'd like to set up my ERV to turn on only if CO2 is above 800ppm but for now I just keep it on and turn it off when I leave.
Setting one up in my bedroom helped improve my alertness and mood. High CO2 in hotel rooms is often why I think I feel groggy waking up.
Volatile Organic Compounds (VOCs) are a type of harmful chemical that can be in the air. Formaldehyde, acetone, alcohol, dichlorobenzene, and pesticides are types of harmful VOCs that are commonly in the home. Formaldehyde in particular is used in the binding glue of wood products used in cheap furniture. VOCs are released as smoke when things are burned like when smoking, cooking, or burning wood in a fire.
The ventilation solutions for keeping CO2 low also work for keeping VOCs low. If you notice VOCs are high when they shouldn't be there might be something in your house offgassing. It could be carpet, furniture, or something burning or decaying.
Installing an ERV in my parent's house helped alleviate some of the allergy symptoms I was having there. I think this was caused by high VOCs but I haven't quite nailed down the source.
Carbon Monoxide #
Carbon Monoxide (CO) is a special type of VOC that can kill you in your sleep. It's produced by incomplete combustion. If you have old gas-powered appliances in your house, or if you're just feeling extra safe, buy a CO meter and put it in your bedroom.
Good air quality makes you smarter and healthier. Good air is a comfortable temperature (65-80ºF) and humidity (40-50%) with low PM2.5 (0ppm), CO2 (<800ppm), and VOC (0ppm).
Keep temperature comfortable with an air conditioner. Keep air humid with a humidifier and dry with a dehumidifier. Keep PM2.5 low with an air filter. Keep CO2 and VOCs low with a window fan or an ERV.
|Window fan + filter||❌||❌||✅||✅|