CO2 and humidity as a cause of health problems

Headaches at the end of the day, struggling to concentrate or sleeping restlessly at night. We often put this down to stress or a busy (work) week. Yet the cause often lies in the air indoors. In every room where people are present, the CO2 level rises. When it rises too far, it can affect your energy levels, your ability to concentrate and your sleep.

The good news: with a few simple steps, you can quickly make the air in your home fresh and healthy again. A CO2 monitor, for example, tells you how high the CO2 level in your home is, so you know when to ventilate. In this blog, you'll read about the different CO2 levels and what they mean, what a healthy CO2 level in your home is, which health complaints a high CO2 level can cause and what you can do yourself to lower the CO2 level again.

What are the different CO2 levels?

Every time you breathe out, CO2 enters the air. When there are (too) many people in a room and too little fresh air comes in, the CO2 level in that room keeps rising. The amount of CO2 in the air is expressed in ppm (parts per million). A CO2 level of 1000 ppm means that 1000 out of every million air particles consist of CO2. Simply put: the higher the CO2 level, the less fresh air there is in the room.

In outdoor air, the CO2 level is around 420 ppm. Indoors, the CO2 level is always somewhat higher, because you breathe, cook and sleep there. To assess whether the CO2 level in your home is healthy enough, we use a scale with four levels. We've set these out for you in a clear overview below.

But how do you know how high the CO2 level in your home is? You measure it with a CO2 monitor. Most CO2 monitors use a specific colour to show the state of the air quality. So you don't need to be an expert to understand the reading. Would you like to know exactly how a CO2 monitor works? You can read about it in our separate blog. Many CO2 monitors also measure humidity. Want to know what the measured humidity tells you? Click here to read our blog about humidity in the home.

What is a healthy CO2 level in your home?

Now that you know the scale, the question is: what CO2 level do you want to achieve in your home? A healthy CO2 level in your home is below 800 ppm. Does the CO2 level occasionally reach between 800 and 1000 ppm, for example when you have visitors or have just been cooking? That's not a problem, as long as the CO2 level drops back below 800 ppm once the cause has gone. Think of around two hours after your visitors have left or after the cooker hood has extracted the cooking fumes.

Does the CO2 level stay above 1000 ppm for a longer period? Then too little fresh air is coming in on a regular basis. That's the moment to ventilate (more).

Pay extra attention to the bedroom!

The CO2 level rises most easily in the bedroom. You spend 7 to 9 hours there in one go, often with the door and window closed. Do two people sleep in a small room? Then the CO2 level can rise to above 2000 ppm at night without you noticing.

That's why you should try to keep the CO2 level in the bedroom always below 1000 ppm, and preferably below 800 ppm. How? By ventilating sufficiently and continuously. If necessary, leave the bedroom door ajar or open a window or trickle vent.

What does a healthy CO2 level do for you?

A low CO2 level means there is enough fresh air in your home. You'll notice this in more ways than you might think:

• You sleep more deeply and wake up feeling more rested;
• You can concentrate better and for longer;
• You suffer less from headaches or a heavy, drowsy feeling;
• The air in your home feels and smells fresh and clean;
• Good ventilation also removes excess moisture, which reduces the risk of mould.

What health complaints can a high CO2 level cause?

You now know what a healthy CO2 level is. But what happens if the CO2 level keeps rising? Below, you can see for each level of the CO2 scale which complaints you can expect. Please note: everyone reacts slightly differently. Children, older people and people with asthma or other lung conditions often notice the effects of a high CO2 concentration sooner.

What does CO2 do in your body?

Why is it that a high CO2 level can make you tired, drowsy or even give you a headache? To understand this, let's first look at what CO2 does in your body. CO2 doesn't only come from outside: your own body produces it constantly.

The journey of CO2 through your body

Your body gets energy from food and uses oxygen to do so. This process produces CO2 as a waste product, just as a campfire produces smoke. Your body constantly has to get rid of this CO2. This happens in four steps:

What happens with a low CO2 level in your home?

CO2 always moves from a place with a lot of CO2 to a place with little CO2. In your lungs, your blood contains more CO2 than the air you breathe in, which allows your blood to release the CO2. If the CO2 level in your home is low, this difference is large. Your blood then gets rid of the CO2 easily, your breathing stays calm and the acidity of your blood stays nicely balanced. As a result, you feel fit and alert.

What happens with a high CO2 level in your home?

If you breathe in air that contains a lot of CO2, the difference between your blood and the inhaled air becomes smaller. Your blood then finds it harder to get rid of the CO2, so slightly more CO2 remains in your blood. This has a few consequences:

• Together with the water in your blood, CO2 forms carbonic acid, making your blood slightly more acidic;
• Sensors in your brainstem detect this. You start breathing faster or more deeply to get rid of the extra CO2, which costs your body extra energy;
• The blood vessels in your brain widen to let more blood through. This can lead to a heavy feeling in your head and/or a headache;
• Researchers believe that together these reactions contribute to tiredness, drowsiness and reduced concentration.

At the CO2 levels you measure at home, your body simply keeps the acidity of your blood within safe limits. A high CO2 level in your home is therefore not immediately dangerous, but you will notice it in how you feel.

What does CO2 do to your ability to think?

A well-known study by Harvard University had office workers carry out thinking tasks at different CO2 levels. At around 950 ppm, they already scored noticeably lower on tasks such as making decisions and planning ahead. At 1400 ppm, the difference was even greater. Research by the Technical University of Denmark also shows that people sleep better and perform better on a concentration test the next day when their bedroom is well ventilated.

Another Danish study shows where these complaints most likely come from. Test subjects noticed nothing from pure CO2 added to clean air, not even at 3000 ppm. But when they sat in poorly ventilated air with the same 3000 ppm, they did get headaches, became tired and sleepy and performed worse on thinking tasks. The difference lay in the substances that people release themselves through their breath and skin, which linger in poorly ventilated air. A high CO2 level is therefore mainly a sign that the air in your home is not being refreshed enough. You can read more about this below.

Not all researchers agree on how big the effect of CO2 alone is. Some of the complaints are probably also caused by other substances that linger in poorly ventilated air. You can read more about this further on in this blog. One thing is clear, though: a low CO2 level means fresh air, and your brain works and sleeps best in fresh air.

How many ppm of CO2 is harmful?

From a CO2 level of around 1000 to 1200 ppm, you may experience complaints that affect your daily life. You are less alert, sleep worse and get tired more quickly. This is not immediately dangerous, but it is unhealthy if it happens often or for long periods.

CO2 only becomes truly dangerous at much higher CO2 levels. In the workplace, a limit of 5000 ppm applies, averaged over an 8-hour working day. Above 40,000 ppm there is acute danger, such as shortness of breath and fainting. You won't encounter CO2 levels this high in an ordinary home. The complaints you experience at home are mainly caused by the CO2 level being too high for a long time.

Those 40,000 ppm are almost a hundred times as much as in outdoor air. That's why the CO2 level in a room rises so quickly when people are present and little fresh air comes in.

Is CO2 the only cause of the complaints you may experience?

Not entirely. Where the CO2 level rises due to insufficient ventilation, moisture, odours and other air pollutants can also build up. Think, for example, of volatile organic compounds (VOCs) released from furniture, paint, cleaning products and air fresheners. A high CO2 level therefore acts as a warning signal: too little fresh air is coming in. So if you make sure enough fresh air does come in, you tackle all these substances in one go.

What can you do to lower the CO2 level in your home?

You solve this with one thing: fresh air. With the four steps below, you can bring the CO2 level down and keep it low.

Why is airing out on its own often not enough?

Opening windows on opposite sides works well, but it also has drawbacks. In winter, your home cools down quickly and your energy bill goes up. And at night, an open bedroom window isn't always pleasant when it's cold or there's a lot of noise outside. That's why more and more people are choosing a ventilation solution that always works. With a mechanical ventilation system a ventilation unit continuously extracts the stale air throughout your home. At the same time, fresh air comes in through the ventilation grilles.

Would you rather not lose any heat indoors? Then a heat recovery unit is a smart choice. This system extracts the heat from the indoor air going outside and then transfers that heat to the fresh outdoor air coming in. That way, you always have fresh and at the same time warm air indoors.

Is the CO2 level persistently too high in one room in particular, for example in the bedroom or your home office? Then a decentralised heat recovery unit is an easy, accessible solution. A decentralised heat recovery unit is fitted in the outside wall of that room and ventilates only that one room. Just like a central heat recovery unit, the device extracts the heat from the air going outside and transfers that heat to the fresh air coming in. The big advantage: you don't need a duct system throughout the whole house. Only an opening in the outside wall is needed, which makes installation much simpler and less disruptive.

Our ventilation tips for the bedroom. What can you do?

• Leave your bedroom door ajar at night, so the air can keep flowing well;
• Open the window or the ventilation grille in the bedroom, even when it's cold outside;
• Air out the bedroom as soon as you get up in the morning;
• Place a CO2 monitor next to your bed, so you can see whether the CO2 level rises at night;
• Is the CO2 level often too high at night? Then choose a permanent solution, such as a decentralised heat recovery unit in the bedroom. Some models have a built-in CO2 sensor or a connection for a separate CO2 sensor. The unit then automatically ventilates more as soon as the CO2 level rises, without your bedroom cooling down.

Remember: healthy air starts with good ventilation!

A high CO2 level in your home often builds up unnoticed. Usually, you only notice it once you experience complaints. By airing out regularly, keeping ventilation grilles open and using a good ventilation system, you keep the air fresh, for yourself and for others. Not sure which solution suits your home best? Then contact our customer service! We're happy to help you find the right solution.

FAQ

In the FAQ below, we've listed the most frequently asked questions about CO2 in the home and its effects on your health. Do you have specific questions about your situation, or can't quite figure it out? Our experts are ready to help!