To Catch a (Health) Thief

Note: This article was originally published in Healthy Indoors Magazine. The author’s views are entirely his own and may not always reflect the views of Foobot.

A healthy home is in balance. It’s comfortable, healthy, and easy to control. Part of what make it healthy are that moisture levels aren’t too high or too low, dust particles are being filtered out, chemical and pollutant levels are under control, and the air just feels fresh. In other words, indoor air quality (IAQ) is continuously managed all year. 

If any of this is missing there is a Health Thief in the house. If you or your family are having health problems that are IAQ related, this health thief is a thief we need to catch. To catch a health thief, we need to understand how he works. To stop him we need to figure out how he’s getting in and what he’s taking.

Here’s how we do that.

IAQ Varies Throughout the Year

From watching multiple client homes we’ve learned that indoor air quality varies drastically throughout the year. That means our health thief may not always be present, and he uses different tools depending on the season.

Our climate has warm, humid summers and pretty cold winters. Your climate may be a bit different, but this is what we see in Cleveland, Ohio.

  • Summer: Often the second best season for IAQ. It’s warm enough for the air conditioner to run, so it helps dehumidify the air and this reduces VOCs somewhat. VOCs are Volatile Organic Compounds, or chemical pollutants. They are often found in cleaning products and building materials. Dr. Richard Corsi of the University of Texas Austin found that VOCs increase with humidity levels, so keeping humidity low is critical. Windows are closed, so outdoor humidity and pollutants aren’t pouring in through them. Linda Wigington and the ROCIS project have shown that outdoor particulate matter largely stays outside when windows are closed. (We advocate for windows to be closed all year to maintain family healthy IAQ.)
  • Winter: Typically the best IAQ. Houses are usually drier in winter because outdoor air is dry, so VOC levels are typically lower. The stack effect is working hard, with cold dry air leaking into the bottom of the home and warm humid air leaking out out the top. Because of this, the house is reasonably well ventilated. The windows are closed, so outdoor pollutants don’t come in very quickly, and are filtered somewhat through building materials and insulation.
  • Spring and Fall: These are typically worst for IAQ. The air and ground are damp. Windows are open sometimes, letting humidity and pollution pour indoors. The air conditioner isn’t running, so humidity levels and VOC levels are uncontrolled. The furnace fan doesn’t run, so there is no filtration of particulates. IAQ is typically awful.

What seasonal variations have taught us is that short term monitoring is not particularly useful. The health of a home changes like the weather. So we like to track IAQ like many track the weather.

What does the Health Thief steal? 

This question tracks back to the 3000 gallons of air we breathe every day. Yes, we ingest 3000 gallons of air, every single day. You don’t drink dirty water, should you breathe dirty air?

we breathe 3000 gallons per day

Over 90% of our time is spent indoors, so the quality of indoor air has a substantial effect on our health. Our body has to deal with all the bad things in the air we breathe.

When humidity is too high, mold, sickness, dust mites, insects, and other irritants proliferate. Childhood asthma has now been causally linked to damp buildings. This is a growing problem because today’s kids spend less time outdoors than maximum security inmates!

When it’s too dry, particulates and flu can become problems as well as dry skin, nosebleeds, and other respiratory issues. I’d argue that humidity is the most important thing to control in most climates, since it has so many direct health effects and home performance impacts. Humidity also affects other common pollutants like chemicals, ozone, and dust.

Particulate matter (aka dust) has been linked by the World Health Organization to increased respiratory disease, heart disease, and lung cancer. A recent University of Bergen – Norway study found that consistently using household cleaners (which contain VOCs) is equivalent to a one pack a day cigarette habit. Since VOC levels are typically much higher indoors than out, this is a growing concern.

The Health Thief also robs productivity. He leaves you tired, foggy, irritable, and more prone to chronic and serious illness. Poor IAQ is beginning to be recognized as a major health care cost. I don’t want to slip into hyperbole, but mounting research is showing that Indoor Air Quality has surprisingly large effects on us. At 3000 gallons a day, is it really any surprise?

Unfortunately, this is a problem that only becomes apparent over the long term. It’s also invisible. We humans are terrible at dealing with problems like this. We need urgent, visible problems to act.

In our experience keeping the Health Thief at bay is not that difficult, but first we have to care. Next we have to expose his work by shining a light on it and making the invisible, visible. Once we care enough to track IAQ, and we have some understanding of when the health thief shows up, we can build a plan to stop him.

Wedding Photos vs. Security Footage

hi-res picture vs low res video

While high resolution testing can be useful for tracking down specific contaminants (i.e. the contents of dust, VOCs or mold), all they are is a snapshot in time. They usually don’t give a picture of the whole house, just of the specific place tested at the moment it was tested. Those have their use in identifying causes of chemical and mold sensitivities, but for our purposes it’s a bit like hiring a SWAT team when you really need a fly swatter.

High resolution snapshots have value, not unlike wedding photographs, but if we’re trying to catch a thief he’s unlikely to stand still for the camera.

How are thieves caught? Often with security footage. It’s low resolution, but it is running all the time. IAQ monitors do the same thing when you want to catch a health thief.

Driving the Point Home

Even if you place a monitor for days or weeks, as I did when I had an Air Advice IAQ monitor, you have to wonder what was going on after the monitor was retrieved. It couldn’t track from season to season. I realized, just like I want a temperature gauge on my car every time I drive it, I also want an air quality gauge in my home every time I’m breathing there. It’s something that should be normal.

This led me to ask the question: is it better to have a lot of information about a little bit of time or a little information about a lot of time?

This quandary reminded me of the Heisenberg Uncertainty Principle which states that you can either know the speed or the position of a particle, but never both. It leads to what is at first a very frustrating realization: you can’t know everything all the time. Could I find a way to be ok with that, like Heisenberg did?

That’s when I got interested in the new crop of surprisingly affordable consumer grade IAQ monitors. My review of them was published in the December 2017 edition of this magazine. I was hoping to find my security camera.

Everything Is a Proxy

The truth of the matter is that we can’t “know” anything, not when the subject is complex. All we can do is measure some things that give us insight into the larger picture, whether that’s looking at the health of a body, home, or another complex subject. Admitting we can’t really know anything, let alone everything, is actually quite freeing. It lets us try to understand what we can know.

This is where proxies come in. According to Oxford, a proxy is “a figure that can be used to represent the value of something in a calculation.” Find the right proxies, and you can come as close to “knowing” a thing as possible, and often with simpler measurements than you might have thought.

FitBit wrist monitors are good examples of a health proxy, because they collect multiple data points. These data points are actually proxies. To have a deeper look at health, we need more advanced testing like MRIs, stress tests, blood tests, etc. But as we discussed, those are only valid for a moment in time. To have a long term look at health we need to find proxies.

The main proxy of FitBit is steps taken, which is imperfect because 1) it’s only accurate +/- 9% and 2) it doesn’t measure some activities like swimming or biking. Because FitBit also measures heart rate, it can be combined with steps taken to understand fitness levels, sleep quality, and general health. FitBit can even be used to predict strokes and pregnancy! All from measuring a few proxies.

Having multiple proxies can lead to an alchemy of usefulness where the weaknesses of one proxy are overcome by the insights provided together with other proxies.

FitBit for Homes

What does a FitBit for homes look like in trying to catch our health thief? As much as we’d love to have a ton of sensors, that’s not practical if we want to keep costs down. Air quality monitors often border on an impulse buy, and impulse purchases stop right around $199. So that’s a really important target price as the device needs to sell broadly enough to be commercially sustainable. The new crop of monitors hover around this $199 cost.

We’ve also found that multiple monitors per home teach us a great deal. This is another important reason to keep the cost down. We can see if a home is uncomfortable if the temperature or humidity spikes up and down quickly, or if one part of the home is much hotter or colder than another. We can see how quickly pollutants travel from one part of the house to another. For example, when something gets burned in the kitchen,  do other monitors take a while to react? And of course we can see if the basement is too damp while the first floor is fairly dry, or vice versa. I can’t recommend multiple monitors enough, but again the cost needs to be a number consumers find “reasonable.”

Indoor Air Quality Proxies

Here are the four proxies I think achieve a useful alchemy. They’re like the telltale signs of the various tools of the health thief – his gloves, crowbar, glass cutter, etc.

  1. Temperature: A good proxy for comfort. If temperature rises or falls quickly, it can be an indicator of either oversized HVAC, high amounts of air leakage, or both. Either is a strong indicator of potential health problems in the home because the home is out of control.
  2. Humidity: While we prefer dew point for comparing indoor and outdoor moisture levels, we’ll settle for relative humidity. Relative humidity also gives you a good idea of when mold growth or high VOC levels are likely. Above 60% mold gets likely, above 70% there’s probably a rave going on somewhere in your home.
  3. Particulate Matter (PM): PM aka dust is looking to be a larger and larger health issue, so we should measure it. PM2.5 (2.5 microns and below) is where the really harmful things start to happen because it can get into our lungs, and it’s where currently available sensors are useful. I’d love to see it go smaller,  since PM1 can go directly into our bloodstreams. For example, diesel exhaust contains tons of very small, and very toxic PM.
  4. Total Volatile Organic Compounds (tVOC): This one will be controversial. Most would want carbon dioxide next, as it’s a proxy for how fresh air is. Many tVOC sensors pick up CO2. They also pick up carbon monoxide (CO) and many common household chemicals. tVOC sensors are multifunctional. While we have to be detectives to figure out what the specific cause is, a tVOC sensor will broadly tell us if IAQ is good or not. If VOC levels consistently spike at night, it’s probably CO2. If the VOC sensor goes off consistently in the basement near the furnace and water heater, it should be checked for carbon monoxide. If VOC levels spike during cleaning, the cleaner is probably loaded with VOCs. One sensor can be tremendously useful, even if it requires putting on our Sherlock Holmes cap.

Those four proxies, particularly if you have multiple monitors, are likely to help you catch the health thief, and continued monitoring will help ensure that he remains banished from your home. If you really push me, I want carbon monoxide monitoring to be next thing these devices track. CO is the only common pollutant that can kill you in short order. Every home that has any type of fossil fuel burning device in or near it should have a CO detector. And tracking low level events is tremendously valuable to avoiding adverse health impacts of CO ingestion.

How to Keep the Health Thief from Returning

Catching the health thief is only the first step, as now you have to figure out how to keep him out. That’s where Home Performance work comes in. It involves gaining control over heat, air, and moisture flows both in and out of a home and within a home.

Gaining control almost always involves making a home airtight first, just like it is crucial that a good boat doesn’t leak. Once it’s tight and you control air flowing in and out of the home, you can control the air within the home through filtration, dehumidification, humidification, and adding outdoor air as needed to replenish oxygen levels. Doing all of that is part of a Home Performance project. You can learn more about those in this column and on my website and YouTube channel.

Once the project is completed, you can use the “security camera” footage from your IAQ monitor to show the improvement from the project, and to ensure that the Health Thief stays banished.

If you suspect a Health Thief in your home, buy a security camera and catch him!