uRAD A3 vs AirVisual

I have featured both devices on my blog uRAD A3 & AirVisual and since both devices allow the user to download a .csv/.txt file with all the registered measurements and as they both have a laser PM2.5 sensor and a CO2 sensor, I decided to compare both of them farewell.

Although I connected both devices side by side on 28/02/2018 at 10:40 am, I will compare the measurements from 5th March 2018 to 7th March 2018 because I wanted to allow the devices to adjust on the new environment, which was my bookcase.

Each device takes measurements at a different time rate. AirVisual, for example, was set to take measurements every 10-15min and uRAD every minute. Unfortunately, I couldn’t set both devices at the same time rate.

The PM2.5 Comparison

I notice that each device uses a different algorithm to analyze the data. The data that the devices store are not raw. uRAD, for example, seems to subtract 3μg/m3 across all readings, as a result uRAD’s graph has more zero values. Of course you can say the opposite as well, that AirVisual adds 3μg/m3 across all readings. The peak value for AirVisual was 25μg/m3, but for uRad was 22μg/m3. Overall they have similar readout but they treat raw data differently.

3DAYS 82000068 PM2.5-3.jpg


The Carbon Dioxide CO2 Comparison

They had a great correlation. You may see a time difference when I compare both graphs one on top of the other, but this is due to the time rate difference each device registers a value.
3DAYS 82000068 PM2.5



I was very happy to see that both devices are great for reading Particulate Matter PM2.5 and Carbon Dioxide CO2. It is absolutely enlightening to know that the device you trust for measuring air quality in your house or work measures pollutants accurately.


Review: uRAD Monitor A3

Who says that everything is made in China or USA? Well, let me introduce you the uRAD Monitor A3 an Air Quality Monitor which is made in Romania, Europe since 2012. The design, firmware design, server software and big data database maintenance and development are all made there and amazingly enough even the unit that I have on my hands is made personally by the CEO Radu Motisan. As a result I am very proud to review it and talk about the cons and pros.


  • Temperature Sensor -40°C to +85°C / 40°F to 185°F
  • Humidity Sensor RT 0-100%
  • Air Pressure Sensor 300-1,100mbar
  • VOC Sensor 0 mg/m³ to 100 mg/m³ reducers – 10 mg/m³ oxidizers
  • PM2.5 Sensor 0 μg/m³ to 1000 μg/m³
  • Formaldehyde Sensor 0 ppm to 5 ppm
  • Carbon Dioxide Sensor 400 ppm to 5000 ppm
  • γ (gamma), x-rays Sensor 0.01μSv/h to 9999.99μSv/h
  • WiFi or LoraWAN or Ethernet or GSM
  • Built-in Speaker
  • LED Light

Read More »

How NO2 affects your health?

I can guess with high accuracy that your answer to the question of the image above is the Healthy Lung. If I guessed right, which I did, then I will advise you to be careful about what you breathe.

These are some gases that chemically poison the body’s oxygen transport systems, preventing oxygen from reaching the body tissues like the Carbon Monoxide CO, which combines with haemoglobin and blocks its ability to carry oxygen around the body, but there are some other gases that cause asphyxiation by producing severe irritation in the air passages and lungs like the Nitrogen Dioxide NO2.

NO2 dissolves in the moisture on any moist tissue surfaces, and forms strong acids or alkalis which then burn the delicate tissues. Health effects are related to its ability to dissolve in moisture to produce Nitric Acid which is a strong mineral acid.Read More »

3 Technologies to Measure Particulate Matter

In this article we will analyze all the available Technologies to Measure Particulate Matter such as PM1, PM2.5 and PM10. This article is trying to answer which type of technology is better and how they work.

First: The Laser Diffraction

Many companies use this kind of technology for their PM sensor like IQAir-AirVisual, Xiaomi, Dylos, Kaiterra-LaserEgg etc. With this technology the sensor is able to figure out the size of the particles and the quantity. This technology is also known as Optical Light Scattering because each time a particle passes and hits the laser beam then an optical sensor, like a camera’s sensor, and with the help of an algorithm will translate how many particles were in the air at that moment. This technology is very stable and the sensor can take measurements fast, typically between 3-10 seconds.

One of the problems that the laser diffraction technology has is how each pollutant is determined by the sensor. For example Black Carbon BC which is an absolute black colored pollutant will absorb some of the light from the laser beam, so it doesn’t react the same as will do a white colored particle which will reflect more light. This problem can be solved with the right algorithm but again the device won’t be able to use the right algorithm for the right pollutant unless we told it which one to use.

Second: The Infrared

The infrared technology is common in less expensive indoor AQ monitors like Foobot, Awair etc. Basic the sensor is a small chamber with two holes on opposite directions which allow the air to pass through. An infrared light is crossing the air there and an infrared sensor is able to determine the light intensiveness. Dimmer light means that pollution is passing through the holes.

One of the problems that the infrared technology has is the estimation of the particles, this technology can’t count particles, it is just guessing. There could be 1200 PM2.5 particles or 300 PM10 particles or 1 gram of sand, either way the infrared sensor will give the same measurement.

Third: The β Beta Attenuation Mass

The β Beta Attenuation Mass technology or BAM is as big and expensive as the length of its name and very uncommon to be found in an indoor environment. Governmental bodies use this kind of instrument like in UK, China etc. Basically, it samples air on a blank piece of filter paper. Then the trapped PM pollution on the paper will be bombarded with some beta radiation. Some of the PM2.5 pollutants absorb the radiation, and the differences on the other side are measured. After that, some mathematical equations are used to determine how the weakening of the β rays translates into a mass of PM2.5. Attenuation is a general term that refers to any reduction in the strength of a signal and in this case the β radiation. The BAM technology is far more accurate than the other two technologies.

There are some disadvantages with this technology too. Humidity can affect the results so proper calibration is always needed.

Some general info to have in mind that applies to all three technologies. If you have two units of the same technology side-by-side, you will still get small variations in results even between 2 BAM monitors. That’s simply because particles in air, especially PM10, aren’t necessarily uniformly dispersed.

Cars vs People and the future

I had a conversations a few weeks ago about cars and what should we do as a society. Should we abandon them or should we find a better alternative? So I thought sharing my personal opinion and of course I would love to read some comments.

Although it is a matter of opinion, automobiles were invented in 1886 by Karl Benz. Immediately people loved the idea that they can move around easily and fast. Since then not much have changed, cars still are burning fossil fuels to move but one thing has happened, the advertisement reinforced the way people feel about cars.

Every good advertiser knows that if he/she wants to make a successful advertisement he/she has to focus on the feeling of the audience to make a successful sell. Today cars offer self-esteem and status to the people and it is wide acceptable that a person with a car, especially a fast and expensive car, worth more than a person who rides a bike. Let’s pay attention on a car ad the next time we watch TV. They present the driver as the most powerful person in the world with success in love life and in businesses. Of course there isn’t only one ad with the same message, it seems that all the companies and all the models inject the same message and all of them are bombarding the subcontinent of a person over and over. For a long time they have washed our minds.

It is so hard to compete with that, it is hard to raise awareness that most cars are bad for the environment and for our health. It is hard to make people think twice that the smoke exiting from a car is a bad by-product of the vehicle. Regulation and concern is needed.

The reason I am writing this article is because in my conversation with the people who already know how bad cars are for the society and want to ban them completely, it made me think that this is practically impossible. Although they are right, I believe that this is utopian and unaffectable. The advertisement has done a significant damage in the society and it will be almost impossible to undo the mind-shaping people have suffered over the years. The car makers will never stop promoting the cars as necessity.

The best alternative in my opinion is to move to green energy (solar-wind) sources and invest on good quality electric vehicles that they will last a long time on the roads.

I don’t own a car but I would like to make a comment about how people interact with cars. For example parents are very protective with their kids, so most of them won’t ride their kids to school on a cold rainy day but they will drive them in a car without thinking twice if they should or not. Of course they could take the bus, but let’s be real here, people have learnt in convenience and the majority of them will choose to drive to school over taking the bus even if it was an electric bus.


We have to move forward and adopt as soon as possible greener energy and transportation. Governments and companies need to understand that we don’t live only for today and future generations have the right to live on a sustainable environment.


Psych Study: When You’re Bummed, You’re More Likely to Buy



2017 Year in Review

2017 has come to its end. Here are the Top 5 articles on See The Air Blog for this year. I want to thank all of my readers for the loyalty that they have given me. Many of you are following me on Twitter and I would like to invite new readers to follow me as well on Twitter because I comment and discuss a lot of topics there too.

The Countdown

5. On the fifth position we can see articles about the DIY Sensors like the OK Lab Stuttgart – PM DIY Monitor and the OurAirQuality DIY PM Monitor which had a lot of visits and people were very interested on them because they offer affordable air quality monitoring plus they fill a market gap for outdoor AQ monitoring for the consumers.

4. On the fourth position is my book See The Air Book. I am very exited for being in this place. People are appreciating the effort I have done and I am very grateful to all of you. Some have offered to translate the book in Chinese and Arabic among others and many have asked me for a Spanish version which it is coming.

3. On the third position we can find the uHoo Review. uHoo is one of the devices with an abundant quantity of sensors for air quality monitoring. People are very interested to know how the device works and the sensors it uses.

2. On the second position we can see a review again and this time about the AirVisual Review. The AirVisual review is for much longer time on my blog so it is normal the position it possesses. Of course it is a great device with one of the best PM sensor out there for the consumers.

1. On the first position for the 2017 ranking we can see the Device Companions. With over 22,000 visits and still counting it has been the number one reason people are visiting my blog from Google and other search engines.