A few years ago, my wife and I began to develop chronic headaches and overall lethargy, waking up in our concrete block home in Florida. We suspected a mold issue, or maybe offgassing from paints or cabinets. Maybe we had a mold problem?
The cause turned out to be much simpler. Our own breath was the cause.
We discovered this by using an off-the-shelf electronic device that measure particulates in air. It checks VOCs and CO2 and reports the findings back to an APP on your phone. In the still of the night, with no active ventilation in the bedroom, our CO2 levels sometimes hit nearly 1500 parts per million (ppm).
As you can see from the data, we were able to solve the problem quickly, by installing an ERV. Before you take the same approach, let’s look a little more deeply at the problem. And bring in some other related topics you need to know about. Most people have no idea how polluted their indoor air can get, especially in older homes. The air you exhale is just one of many invisible toxins that might be making you sick.
How Much CO2 is Too Much?
Different organizations measure risks from excessive CO2 differently.
For example, ASHRAE, the organization that sets ventilation targets for home construction in the U.S., emphasizes the number of air changes per hour (ACH) in a home, not amount of pollution. Europe’s Federation of European Heating, Ventilation and Air Conditioning Associations (REHVA) offers a sort of traffic light metric of risk. CO2 levels less than 1,000 ppm fall in the green zone, 1,000–2,000 ppm-yellow, and greater than 2,000-red. For infants and people with respiratory issues, a level less than 1,000 ppm is prudent.
In my experience, levels around 1500 ppm overnight were enough to induce frequent headaches and cognitive “haze.”
Most homes, of course have many other particulates floating around, as shown in the chart below. Increasing ventilation to the home has the effect of “diffusing” these pollutants. In other words, it may not remove them completely, but it greatly lowers the levels.
What’s the Best Solution?
You have several options for dealing with self-pollution from CO2. For immediate relief, you might just open a window. But that’s not an automatic fix. It places you at the mercy of climate and air pollution. You’ll be wasting energy heating or cooling extra indoor air to replace what’s lost through the window. And your outdoor air quality may be WORSE than indoor air, depending on external conditions.
I guess if you live atop a mountain in Colorado, you might expect the air outside to be cleaner than indoors, but in most other places in the U.S., at certain times of year, that’s simply not the case.
For example, as I’m writing this, both Central Florida and Oregon are under extreme warnings about poor air quality. The culprit: burning forests. I didn’t use the term “wildfire,” because in Florida most fires are so-called “controlled burns,” where huge volumes of toxic smoke are released into the air.
Without getting too far afield from our look at indoor CO2, wildfire smoke has also become a major air pollution problem now, across most or the United States. It’s entering homes, and it’s far more dangerous than most people realize.
How does wildfire connect with home ventilation? It adds a complicating factor, and makes the idea of “just opening a window” a much less certain way to improve indoor air.
To protect your family from recurring wildfire smoke events, you’ll not only want to look at balanced fresh air ventilation with ERVs, bath fans and range hoods, but also some form of filtration, such as HEPA or MERV 13 filters, that can capture smoke particulates. Some of the newest ERVs also have “smart” features that increase speed or shut off the unit when exterior smoke levels are too high. They can also activate automatically in indoor CO2 levels spike above about 600 ppm.
New Rules, New Tools
If you’re buying a newly constructed home, you have an advantage. New ASHRAE rules mandate higher levels of ventilation. Builders will essentially have to provide some form of mechanical ventilation, not just trust to winds and weather.
If you’re looking at the air quality in an older house, I’d recommend you tackle ventilation in a deliberate way. First, get yourself an air quality sensor, and find out what’s going on. Is it your breath, proximity to the garage, or cooking fumes that are polluting the air?
Then decide which mechanical tools can help. In the short term, you may be able to run your ducted furnace or central air differently, sending more airflow to rooms during sleeping hours.
I’ll be hosting a free live webinar on the topic of ventilation in homes on January 28 at 2 PM ET, where you can ask questions and see what different ventilation methods look like. We will have a couple of other experts online too. Please join us if you can.