In Dyson app, we can see the NO2 in absolute value of 1,2,3,4 or 5 …… for indoor reading however for the outdoor reading we are seeing PPB reading. Due to the different value, we can’t really compare if the room air is really much better than outside as they are of different units. Anyone notice and know why the difference in the measurement units.
Solved
NO2 values
Best answer by Stuart
Hi
This is an interesting question, thanks for creating a posting about it.
To help answer this, we first need to provide some context to what NO2 are, how the gas is made up and how the sensors across Air Purifiers account for their readings.
NO2s readings are made up from several different group of gasses, including Nitrogen Dioxide and Oxidising gasses. These are usually seen from cooking gasses and vehicle emissions.
Due to the number of gaseous sources, a fixed PPM/PPB for every in-home environment cannot be automatically generated. Instead, the onboard sensors use a baseline and reacts to changes in the local environment using a logic algorithm (Automatic Baseline Correction).
This algorithm eliminates any sensor drift and drives the sensor to quickly reduce the baseline when a time of low measurement is sensed.
Using the above baseline and detection method, we can quickly identify peaks in the sensor readings and attribute this to the presence of NO2. The greater the peak, the greater the Dyson AQI shown. This method is commonly recognised.
For this reason, we cannot show the active PPM/PPB level in the Indoor Air Quality readings.
Outdoor readings are provided from the likes of Weather Stations and advanced sensor node, both of which have access to a large array of data and a detection method more advanced that what is on offer commercially.
I hope this has helped to answer your question.
Thanks,
Stuart
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+13Hi
This is an interesting question, thanks for creating a posting about it.
To help answer this, we first need to provide some context to what NO2 are, how the gas is made up and how the sensors across Air Purifiers account for their readings.
NO2s readings are made up from several different group of gasses, including Nitrogen Dioxide and Oxidising gasses. These are usually seen from cooking gasses and vehicle emissions.
Due to the number of gaseous sources, a fixed PPM/PPB for every in-home environment cannot be automatically generated. Instead, the onboard sensors use a baseline and reacts to changes in the local environment using a logic algorithm (Automatic Baseline Correction).
This algorithm eliminates any sensor drift and drives the sensor to quickly reduce the baseline when a time of low measurement is sensed.
Using the above baseline and detection method, we can quickly identify peaks in the sensor readings and attribute this to the presence of NO2. The greater the peak, the greater the Dyson AQI shown. This method is commonly recognised.
For this reason, we cannot show the active PPM/PPB level in the Indoor Air Quality readings.
Outdoor readings are provided from the likes of Weather Stations and advanced sensor node, both of which have access to a large array of data and a detection method more advanced that what is on offer commercially.
I hope this has helped to answer your question.
Thanks,
Stuart
I found this and am very interested. Initial question is the same: why we don’t have ppm or µg/m3 metrics for NO2.
Now that I read the response above, the question becomes:
You are stating that “the onboard sensors use a baseline”.
How is such baseline determined ? is determined at the factory when the product is manufactured OR is determined in the room at home where I have positioned it ?
Thank you.
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