Back Indoors – Indoor Air Quality is still a thing, here is why!

Autumn and Winter are almost here for the Northern Hemisphere which means a vast majority of the population is going to leave terraces and other open outdoor spaces for indoor spaces (offices, classrooms, homes, indoor restaurants, etc). Covid-19 is still present, but most importantly, we are going to breathe lots of indoor air. We need to take control of the air we breathe as indoors is much easier to diminish the quantity of pollutants we inhale than been outside.

Covid-19 has ruined the lives of many people, personally, I believe that it is very easy to combat the spread of the virus in enclosed spaces, but we need to follow the rules of proper ventilation and purification combined. Scientists have developed various kinds of technologies that can capture pollutants and pathogens. I don’t want to focus very much on the pandemic rather than how important is to breathe clean and fresh air indoors for so many other reasons.

I know from fact that many people don’t have lots of options when it comes to managing indoor air because purchasing an air quality monitor or an air purifier or a central ventilation system is difficult. People with limited financial resources also deserve clean air, for this reason, there are some great DIY solutions that I will present at the end.

Let’s make something clear, good air quality (AQ) is not enough. We need excellent AQ in order to achieve excellent health. We focus on having fit bodies by drinking and eating healthy or even exercising every day, but we don’t take a closer look at the air we breathe (which by the way, we inhale 11000 liters/day). Health needs a holistic approach, and the air we breathe makes us who we are. I am currently translating WHO new Air Quality guidelines and it states that there is no safe limit of pollution. We have to fight for the best air possible!

Countless scientific studies conclude that dirty air directly affects every single organ in our bodies, it is even responsible for the obesity of our children. Lungs, heart, liver, brain are a few of the human organs that suffer damage when we inhale toxic pollutants. These toxic pollutants are not rare but are very common chemicals aka VOCs in households and offices because we use thousands of them every day. Paints, paint strippers and other solvents, hygiene products, aerosol sprays, wood preservatives, cleansers and disinfectants, moth repellents, and air fresheners to name a few, contain a lot of VOCs.

VOCs are not the only threat though! Particulate Matter aka PM1/2.5/10* is also very dangerous and the number one culprit is wood and biomass burning for heating or cooking or for any other possible reason we burn stuff. PM1/2.5 is also emitted when we burn fossil fuels as vehicles or ships or planes do. However, PM is not the only pollutant that is emitted when we burn something. VOC including formaldehyde, PAHs, and many more toxic pollutants are released into the environment. Even when we drive those pollutants out of the house through a chimney, they easily come back to us and deteriorate indoor air quality according to a scientific study.

Wildfires pollution (smoke) enters our homes too, and according to a study, it depends on our behavior how fast indoor quality will deteriorate. Also, newer buildings are better designed to keep the pollutants out.

Another not-so-toxic indoor pollutant is carbon dioxide (CO2). CO2 isn’t going to kill us but it is going to make us sleepy and it lowers our cognitive abilities aka our ability to think and be productive. Recently, experts use CO2 levels as an indicator of ventilation rates in order to minimize the virus load (flue, covid19, etc) in public indoor spaces (schools, offices, restaurants, etc). The fresher the air the better, but remember the air has to be fresh and clean.

What can we do?

Three easy and mandatory steps to make sure indoor air quality is always excellent.

  1. Quantify the pollution
  2. Filter and ventilate smartly
  3. Work together

1. Quantify means to measure the pollution or the air quality indoors. However, I always recommend having two air quality monitors, one indoors and one outdoors. The indoor air quality monitors need to measure at least 5 parameters; PM2.5, CO2, VOC, temperature, and humidity. Each of these parameters will help us keep indoor conditions in check for better health. The outdoor air quality monitor has to measure at least 3 parameters; PM2.5, temperature, and humidity. By comparing the outdoor and indoor conditions we can take better decisions when it comes to ventilation. If outdoors the PM2.5 concentrations are high we tend not to open the windows because pollution will enter inside. We look for low PM2.5 ambient concentrations when we want to ventilate our houses.

2. Pollution is not something that only comes from outside (wildfires, traffic, industrial or agriculture sources). We emit indoor pollution while cooking or lighting a candle, cleaning, etc. For all of these outdoor/indoor reasons, it is a good idea to filter the indoor air. Indoor air purifiers do a great job when they are equipped with HEPA filters as they trap effectively all PM. Something air purifiers cannot do is remove CO2 and in this case, we need to ventilate. In order to filter and ventilate smartly, we need air quality monitors.

3. Work together means understanding that our everyday actions can affect others. We need to think altogether more sustainable on how to transport from one place to another without asphyxiating our children lungs, how to cook and heat our houses without chocking our neighbors and how to stop being so selfish beings. We live in communities and we need each other.


There are many air quality monitors and air purifiers in the market, I have reviewed many of them (Awair, Airthings, Airthinx, ATMO, Kaiterra, AirVisual, uHoo, BRISE, Healthy Air Technology, SPARROW, Djinn Sensor, uRAD Monitor, PurpleAir…) just search here on the blog for a review or the comparison list. Price is a criterion for some, the quantity of sensors is a criterion for some others, but definitely, quality and product support is something that you need to keep in mind so please avoid generic Amazon products.

For those with limited economical resources, DIY solutions for air quality monitors can cost as low as US$32 like the Sensors.Community with 13.693 active sensors worldwide is something worth considering. There are DIY air purifiers aka Box Fan too, have a look at Smart Air Filters, but there are many more ideas out there, just Google “DIY air purifier“.

*PM1/2.5/10 the number 1 or 2.5 or 10 describes roughly the aerodynamic diameter of the particles, aka how small or big they are in micrometers (μm).


6 thoughts on “Back Indoors – Indoor Air Quality is still a thing, here is why!

  1. I’ve been digging into sensors a bit, I was originally thinking of a purple air + usb powered air filter for my campvervan then found out about the wynd plus which would be a more streamlined solution. The general consensus seems to be that real world results aren’t as good as purple air, but once calibrated it does a good enough job (I read your take of it on the halo sensor a while back, but firmware/software updates since seem to have made some impact).

    You’re probably aware of these studies, but I figured I’d share them for you & others as this site has been a helpful resource for me.

    Liked by 1 person

    • The only thing which has me leaning purple air at this point is the fact there are different profiles available for it. We’ll be shifting from smoke along the mountain west (iirc they had issues with PM2.5 woodsmoke in the past which has been largely dealt with via different profiles), to dust in the southwest, to random particulate / mold I suppose in the PNW of the US.

      I don’t care so much about purple air’s long term historical tracking (though it’d be nice to look at!) and we wouldn’t really be adding to the public record in a meaningful way with it moving around a lot and being “indoors”. Having the wynd unit running off of USB in the van and being able to take the tracker off on hikes or backpacking trips (turning it on occasionally due to low battery life, but still) could be useful or interesting and being able to just see the data directly on my phone via bluetooth vs having to be online is a bonus.

      With a 15% coupon at the wynd site, getting an air purifier that is tied to a fairly accurate if needed to be calibrated when shifting areas and a tracker for $170 seems more appealing than spending $200-$250 for a purple air (the PA-II seems noticeably more accurate than the PA-I with the extra sensor) and then getting some crappy $30-40 air filter off amazon etc.

      Any thoughts? The main thing that is an unknown for me is the utility of Purple Air being calibrated / adjusted by various groups and agencies due to the wide adoption of it.

      Liked by 1 person

      • Hello Carl, thank you for your comment and the links you have shared with us.

        Indeed, PA-II is a bit expensive and for us in Europe even more after customs fees. It is backed by many scientific groups mainly in the US.
        Personally, I prefer a DIY solution like the Sensor.Community or an inexpensive Smoggy. I didn’t see a lot of value on having 2 sensors inside a monitor apart from the fact that when one sensor malfunctions you have the other as a “reference”.
        PA are as calibrated as any other monitor. In order to calibrate a monitor you need to co-locate it with reference monitors in the same location you are going to install it because climatological like humidity conditions affect the sensors.

        I was disappointed with Wynd so it’s hard for me to recommend it. However, I had the original version that come out from the kickstater campaign which means they may have done adjustments to the hardware which is currently sold. By re-reading your comment you have the portable Wynd AQ monitor which I haven’t received.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s