Your health and carbon dioxide (CO2)

By | 5th April 2017

Fresh air is good for your health. Carbon dioxide is not. What does it mean and what impact does carbon dioxide (CO2) have on your health?

How healthy is your office and home environments? And how does it compare to the outside? Let’s find out.

CO2 and health – Theory

Indoor air quality is a vast subject and I don’t expect to cover it better than an Wikipedia article. Suffice to say – quite a few metrics to track, but the most common and universal one is the Carbon dioxide (CO2) level.

And without going into much detail – typical outside CO2 levels measure from 350 ppm (particles per million) to 450 ppm (particles per million).

What’s a good level that CO2 should be at? The maximum indoor CO2 level considered acceptable is ~1000 PPM.

There are multiple sources and standards for this. As a general “rule of thumb”, for a healthy environment – [outdoor CO2 ppm] + [indoor CO2 ppm] < 1000 ppm. Truth is – strictly speaking nobody knows exactly when the adverse effects start. Below image is a very general illustration.

CO2 levels

CO2 levels

What happens if these levels are above the norm? And I’m not talking about extreme levels here. This study (and one more study) mention that:

Relative to 600 ppm, at 1,000 ppm CO2, moderate and statistically significant decrements occurred in six of nine scales of decision-making performance. At 2,500 ppm, large and statistically significant reductions occurred in seven scales of decision-making performance (raw score ratios, 0.06-0.56), but performance on the focused activity scale increased.

Direct adverse effects of CO2 on human performance may be economically important and may limit energy-saving reductions in outdoor air ventilation per person in buildings. Confirmation of these findings is needed.

Impact of CO2 on human decision-making performance. Error bars indicate 1 SD.

Impact of CO2 on human decision-making performance. Error bars indicate 1 SD.

CO2 – Current (sad) state of affairs

CO2 impacts a number of other things as well. There’s a recent documentary with Leonardo DiCaprio that talks about global warming and climate change – Before the Flood. “A look at how climate change affects our environment and what society can do to prevent the demise of endangered species, ecosystems and native communities across the planet.” I would say that the question covered is put in a very politically correct and mild way, because not having fresh air is a catastrophe. I mean – as long as somebody is still concerned about being healthy enough to think clearly.

The documentary talks about a spiral effect and if it spins out of control (and there is consensus that it already has), we could see very dramatic rise of CO2 in atmosphere is very short periods of time. Literally meaning – your lifetime.

Before this I’ve never paid much attention to global warming, what it means and what are the trends. But I think everyone understands and can relate to what “running out of fresh air to breath” means. Pictures below demonstrates our current state of events.Atmospheric CO2 increase can and will be bad for your health

Atmospheric CO2

Atmospheric CO2 from


So, to measure air quality you need a CO2 meter. Those are a bit pricey. Some of the more available ones go for around ~130 USD.

Example CO2 Meter

Example CO2 Meter

Typically these are combined together into one product that covers date, time, temperature and humidity.

I’ve been lucky to get my hands on a more advanced Netatmo Weather Station, which has nice additional features. To name a few – both outdoor and indoor modules, data reporting for a period of time (humidity, noise, temperature and others), smartphone application, notifications for weather changes an other perks.

Netatmo Weather Station

I’ve been using it for a while now, but only recently decided to check how good the air quality in the office. Before testing I’ve considered that our office is excellent in terms of ventilation.

Measurements and results – Home space

My home space is an apartment and it is ventilated only through windows. In Latvia many people consider that exhaust pipes that kitchens and bathrooms are equipped with are ventilation. No, they’re not, because they do not supply fresh air, they’re exhaust. Same goes for Air Conditioning units. Many people consider them as a supply of fresh air. Wrong again, most of them are cheaper split systems and do not supply fresh air. What’s even more troubling – in our country even the engineering and building experts most often do not understand this.

But, in truth, it’s more a question of supply/demand, because currently there is no demand whatsoever for fresh air intake devices in the apartment market, typically cheaper alternatives are used. Some of them include:

  • “Winter” window ventilation
  • Open windows
  • Air valves mounted into PVC windows
  • One or two air grates in the walls
  • (surprisingly a way that works in older buildings) Wooden windows and “not energy efficient” buildings

In the private house market segment, the above is still true, with some exceptions that are quite expensive – heat recovery ventilation systems. These have high requirements – initial investments ($$$), planning air pipes during repairs and high maintenance costs – mostly due to electricity bills (used to heat up the incoming air to compensate for the temperature difference). So, in our Latvian climate, you’re easily looking at extra ~150 kWh per month.

Now, to jump into the metrics. Here is how Netatmo Weather Station displays common data.

Netatmo Weather Station mid-March 2017 apartment data

Netatmo Weather Station mid-March 2017 apartment data

The space is sufficiently ventilated. Night hours could use improvement. Winter months are more complicated. Humidity levels like this are common in months when using heating. Depending on how “energy efficient” and sealed the building is – results from open/closed windows may vary.

Measurements and results – Office space

Netatmo Weather Station April 2017 office space data

Netatmo Weather Station April 2017 office space data

I’ve been pleasantly surprised by there results. Our open type office space has a lot of people and keeping CO2 levels under control would be a challenge. Lucky the ventilation system keeps up and CO2 levels are optimal (sometimes slightly exceeding recommended 1000 ppm).

Temperature results are a bit weird, but will get better when Air Conditioning kicks in.


To summarize the above and to state the obvious.

You’ll be surprised how fast fresh air runs out. Even if you’ve ventilated the room one hour ago – chances are CO2 levels are already at their peak.

Apartment should be constantly ventilated. Even in the winter. Two times per day with full open windows (the best and fastest way). And using “winter mode” ventilation in PVC windows. I would not worry about saving on heating costs. Heating systems are designed to account and compensate for this. Your health is not planned to compensate.

Summer time – keeping open windows throughout the day is a good idea. Maybe not all of them, but most. And looking into alternatives if living on lower floors/noisy streets.

Most issues come from night time in rooms that do not have open windows. CO2 levels there build up fast and can easily go over 1000 and 2000 ppm. Sleeping with open (or at least slightly open/winter mode ventilation) windows is a must. I would be careful with that during winter months, as some people are prone to catching cold.

Office workers have it harder because keeping windows (if any) open will not be enough for meeting rooms full of people. That’s where ventilation systems and experts come in. And that’s why most offices have these shiny silver pipes hanging over your head or built into ceilings/walls/floor. I would avoid small meeting rooms filled with people on several hour meetings.

Finding a balance on how much fresh air is needed and how often to ventilate is individual.

I’ve found that Netatmo Weather Station helped me wrap my head around this subject and improved my habits. And if these habits make me more healthy and productive in the long run – all the better.