Real Life Experiment – Indoor vs Outdoor Air Quality

There are countless times that I stretch the importance of monitoring and managing indoor air quality by keeping an eye on the outdoor air quality/conditions.

In this experiment, I want to demonstrate that it is hard to manage indoor air. I want to state that indoor spaces should be subject to 24/7 monitoring and not a periodic inspection.

The graph below demonstrated that indoor AQ gets influenced by outdoor air and on top of that, the polluted air lingers for a longer time indoors unless there is a mitigation plan (aka filtration) in place.

The graph shows PM2.5 data during a period of 48h hours of continuous monitoring with an indoor and outdoor air quality monitor. The house uses natural ventilation to keep CO2 and VOC concentrations low. During poor air quality events, windows and doors were kept closed.

Once the neighbor started a domestic fire (for an unknown reason) both indoor and outdoor environments were equally influenced. Unfortunately, as automation wasn’t active, it was too late to stop outdoor air from coming indoors. Outdoor air improved faster due to winds and faster dilution of the pollutants, but the indoor air was above WHO AQGs recommended levels (5 μg/m3) for the rest of the day.

Then another fire event of a bigger magnitude occurred, and once more it influenced indoor air in a great extent. The overall 48h average PM2.5 values for the outdoor and indoor air were 8.6 μg/m3 and 13 μg/m3, respectively.


All in all, my exposure to fine particulates was higher indoors, even though the source was outside the house (about 60 meters away). Air purifiers or a central ventilation system with high-quality HEPA filters are recommended. I have found from past experiments that a positive pressure solution is more effective (in most cases) as it keeps VOCs and CO2 at low levels indoors.

Ban Wood Smoke – Stickers

In my effort to help clean air communities to raise awareness (I am not only words), I decided to design three simple circular stickers which I will distribute to the communities once the poll is closed and you have selected the best sticker.

Choose one between the three of them and apply to get stickers once the poll is closed. You can apply for the winning sticker via the contact page. Thank you!

If someone (company, non-profit, individual, etc) wishes to support my effort to print and ship the stickers feel free to reach me.

Size Matters: Why is important to know the Particle Size Distribution?

In a constant effort to educate the community, I highly recommend you to attend my upcoming webinar “Size Matters: Why is important to know the Particle Size Distribution“. The webinar is scheduled for the16th of November, 2022 at 8am EST.

Although it is a business oriented webinar, I will also try to educate in simple terms the attendees on what is PM2.5 and why it falls short as it doesn’t reveal in detail the make up of air pollution.

Unfortunately, any value of PM2.5 can represent a wide variety of particulate distributions, and although it has helped researchers in the past to identify the relationship between air pollution and health issues, nowadays, it falls short. We know that the smaller the particles deeper they travel inside the human body. Quantifying the different sizes can help us understand better the effects particulate pollution has on human health and mitigate air pollution appropriately.

See you there!

The Dark Side of the Wood Stove Industry

You probably have seen “cozy” images of fireplaces or wood stoves with happy people, a blanket around them, and a hot beverage and you may have thought that’s something very appealing, I want that! Well, I would suggest thinking twice before taking that decision and if you have already taken it, maybe it’s time to undo your mistake.

You see, people get sick thanks to these “cozy” elements in houses. It’s very hard to undo the brain wash the wood stove industry has done all of these years but we have to realize that wood burning is neither sustainable nor healthy.

Many claims that biomass is sustainable but this is a myth. A story designed to push people into spending money for status or simple ineffective heating. You see, clean energy (wind, solar, etc) doesn’t require the user to buy fuel, logs, or pellets every season. It is there for us but doesn’t generate constant revenue for the companies.

People who live in neighborhoods where wood burning is present suffer from many health problems. The most common is asthma but what we don’t consider is why those people suffer from asthma in the first place. Air pollution is the predominant reason and wood burning asphyxiates neighborhoods with a cocktail of toxic pollutants.

I asked people on social media to send me legit images of the situation and I got a gazillion of them. From Poland, Germany, the Netherlands, Belgium, the UK, France, and many more countries. I wasn’t able to process all of them but there is a small sample below.

This year will be even tougher for the European countries as the energy crisis and the ridiculous high electric price will force people into alternative “cheap” heat sources. I quote “cheap” because we pay it with life expectancy and medical bills later on. I wanted to warn my followers on Twitter that they need to find ways to protect themselves from air pollution due to wood burning and to my pleasant surprise some people are already aware.

I know that in theory, it may sound easy, but in reality when your monthly salary is not enough to cover expenses you need to find ways to survive. What I want to make clear though is that we need to think long-term in order to break this vicious cycle. In a 2021 study, researchers found that the same pollutants that exit from a chimney will also influence the indoor air of the same house.

Of course, in our modern society, most people don’t care about their neighbors, but they should care about their well-being. A 2022 study from the same researchers gives insight into why wood-burning stove users continue to burn when presented with data on indoor exposure. The way AQ data is presented to the homeowners plays an important role in the decision. 

I don’t think people will change their minds just because I share scientific studies (123, …) where there is a clear correlation between wood burning and health. It’s a fact that we don’t appreciate air the same way we appreciate other goods (food, drinks, materials).

I had a conversation with a journalist last week about the fact how the industry of wood burning is selling lies to people. He told me that the salesperson stated that the smoke that comes out of their pellets is safe because it is “natural” wood. Moreover, the salesperson stated that the smoke is not contributing to climate change. Of course, everything was lies. Initially, the journalist wasn’t educated on the air quality/pollution issues and didn’t fight back but after explaining to him the chemistry, he was shocked about the way they tried to manipulate him. Thankfully, he didn’t broadcast their lies.

Political willingness is needed in the equation to fix the air. Unfortunately, money moves the world but we need directions and legislation that will navigate companies and people in the right direction. Don’t buy into the lies that wood or biomass is sustainable.

Modern Houses & Indoor Air Quality 🏡

One will think that the more modern the house, the better the indoor air quality. However, that’s not always the truth as recently I discovered that many houses have inadequate appliances that will create harmful air pollutants and some of them will falsely mitigate contaminants by creating a false sense of remediation.

Example #1

Gas cooktops are a must according to good chefs as the pans are able to heat immediately and you have more control of the heat. That’s not true as the new induction cook tops are able to heat the bottom of the pans as fast without releasing harmful pollutants like Nitrogen dioxide.

Gas stoves, especially when unvented, can be the number one source of indoor air pollution. According to new research, gas cooking produces about twice PM2.5 as electric cooktops; including nitrogen dioxide (NO2), carbon monoxide (CO), and formaldehyde (CH2O). 

Example #2

Hoods, extractors or over-the-range microwaves “with” exhaust are important while cooking. However, the over-range microwaves that come with an extractor end up reticulating air indoors without proper filtration.

Most houses in the US have these false products that give the sense of remediation but they actually contribute to indoor air pollution. Look at the holes this aluminum filter has! These products are designed to trick customers and spend electricity without any measurable results. Shame on the companies that sell them!

Example #3

Once more, most gas heaters, which are installed indoors without any proper ventilation, result in more unnecessary indoor air pollution. They release the same pollutants as the gas stoves because the combustion of the “natural” gas, which is a fossil fuel, creates all of the above pollutants.


Although my cooktop doesn’t use gas, particulate matter is also released when we cook. I managed to mitigate the pollution that comes out of the pots while cooking with a portable air purifier (AirBubbl by Rensair) which was able to fit above the microwave and capture on the HEPA filter most of the particles by easing the air I breathe indoors.

Finally, I keep windows open when possible and the bathroom extractor on in order to dilute the indoor air with outdoor air (when the ambient air is clean). CO2 and VOCs drop significantly with this technique and PMs are managed well.

It is hard to make drastic changes to an apartment when living on rent, but there are a few techniques that will help us remove pollutants from the indoor air. Next, I will have to buy a high CADR number indoor air purifier with a good HEPA filter.

The Truth about Indoor Air Quality

Not lots of people are ready to accept the truth or understand it. We dismiss important information when it is not visible “out of sight, out of mind” and we get influenced when something is shiny and pretty.


Poor air quality won’t kill you (at least not immediately and depending on the pollutants), but do you want to be an average employee, athlete, parent, student, or the best? Do you want your employees to work in mediocre conditions and perform poorly, or do you want them to be vibrant and productive?

Excellent indoor air quality will boost the performance of all. The main environmental parameters you must consider addressing are four, Particulate Matter (PM2.5), Carbon Dioxide (CO2), Temperatures, and Humidity. I haven’t included VOCs because poor ventilation and high CO2 levels will result in high VOC levels, so I made things easier.


Air pollution is not easily understood by most people mainly because it is invisible. No one is going to drink a glass of water if the water is dirty but how many times have you had to breathe second-hand smoke, vehicle fumes, or wood-burning smoke! I will say with certainty there were many times and you don’t even worry or remember about it.

The respiratory system isn’t designed to deal with fine particulates and other pollutants. The gastrointestinal system, where solids and liquids get digested, can deal with contaminants because it can get rid of them through the two avenues designed by nature. Sure drinking or eating extremely spoiled food and drinks can lead to deadly diarrhea. However, the respiratory system cannot do something similar and pollutants get accumulated inside the lungs. The smallest pollutants like PM1.0 and gases are distributed through blood even to the brain.

Sure, you can cough, but once particles are inside us they are stuck around the walls because of the fluids. Here is an example of an adult male who was a non-smoker and his lungs are black because of the indoor and ambient pollution. He donated his body to science, and now people can see “him” at the museum of Granada in Spain.

I don’t want to repeat myself and tell you that you spend 86.9%NHAPS of your time indoors, but it’s a fact!

Air is the most important element because without it you only have 3 minutes to live. You literally remove years from your life when pollution is inhaled.

Finally, I believe it is time for researcher to look into the size distribution of the particles rather than generic PM2.5 values that can represent many potential size distributions.

Have you noticed Climate Change?

I have this simple question. Have you noticed Climate Change?

I believe the summer heat has helped many in the northern hemisphere to notice that something is going on. However, climate change is not only extreme heat but a lot more.

Lots of news are covering the record temperatures that are registered in places never seen before. Lots of articles are talking about the deaths these high temperatures cause. All of them are true, but no one mentions the effects on the environment that supports our food chain and the animals that live on this planet too. Crops and animals, suffer a lot, and they don’t have an air conditioner to cope with the heat or an air purifier to cope with the air pollution.

Ozone (O3)

Ground-level ozone causes more damage to plants and trees than any other air pollutant. Ozone penetrates leaves through stomata (tiny openings present on the epidermis of leaves) during gas exchange. Ozone is a strong oxidant, and it causes several types of symptoms, including chlorosis (yellowing of leaf) and necrosis (the death of the tissue).

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Low-Cost Sensors, Do They Hold Up To The Hype?

Low-cost sensors have helped communities see the air quality, but experts are still debating whether data are accurate or not. In many cases, monitor manufacturers have to turn to data manipulation in order to get accurate results, but it is time to step up by deploying better sensor technology.

The technology exists and we should take advantage of it as soon as possible. Almost always, the first thing I am asked about sensors is how accurate they are. Well, this question has a very tricky answer. In many cases, we measure accuracy by comparing a low-cost sensor with a reference monitor, which worths thousands of dollars. However, the comparison is not always fair. For example, if the XYZ company sends their monitor for evaluation during a high humidity season then unless they have a heater or dryer at the inlet to remove humid droplets of water from the samples before measurement then the results from the correlation would be catastrophic.

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Fireworks are Bad New for your Body

Fireworks or pyrotechnics are used heavily to this day in many places around the world to celebrate various events. People have them associated with fan and parties, so they are not very open on hearing that they are bad for our health. Fireworks elevate air levels of particulate matter with several metallic components and gases during their explosion. Studies show that hospital admissions with respiratory issues increase during similar events all around the world.

The color of the fireworks is subject to the metals they mix, and while these metals heat from the explosive materials, they produce various color hues.

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Cars vs People in the USA – Air Quality

Last week was CleanAirDay. I love days like this when a collective effort is made to raise awareness of such an important problem in modern society. Most importantly the new generation of citizens is taught about the importance of excellent air quality and the dangers of air pollution.

For the past few weeks, I have been living in the US near Boston and I am still trying to wrap my head around those super monstrous vehicles people use to commute from one place to another and how towns are designed to force people to drive everywhere.

I am the only person that walks to work or to the grocery store. Literally, I don’t see other people walking here. It’s tremendous!

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