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Key Points

Key Takeaways

  • 1

    See the Air

  • 2

    CO2 1000ppm: When carbon dioxide concentration exceeds 1000ppm, human cognitive ability drops by 15%. Drops by 25% at 1400ppm. Getting sleepy in meeting room is not because boring, but because oxygen is thin

  • 3

    Aranet4 Home: Professional CO2 monitor made in Latvia. Uses E-Ink display, battery lasts several years. Since log can be taken with smartphone app, pattern of 'When ventilation is needed' can be grasped

  • 4

    Dyson Purifier Big+Quiet: Dyson history's quietest and most powerful air purifier. Decomposes even formaldehyde. CO2 sensor also attached, but Aranet4 has faster response speed

  • 5

    Ventilation Strategy: Opening window is best solution, but pollen and noise enter. So, look at CO2 monitor and ventilate only at moment when 'Limit value' is exceeded. This is most efficient

Introduction: Suffocation of Brain

2 PM. Sudden drowsiness. Drink coffee, but doesn’t work. That is not caffeine deficiency, but oxygen deficiency.

When human breathes in closed room, CO2 concentration rises in blink of an eye. You are living by breathing your own exhaled breath. That is slow suffocation.

1. The Gold Standard: Aranet4 Home

It is “Rolex of CO2 monitor world”. Cheap sensor (Non-NDIR method) outputs nonsense value, but this is peerlessly accurate. E-Ink screen has wide viewing angle, value can be seen from anywhere in room.

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Aranet4 Home

App graph function is excellent. If you look at change of CO2 concentration while sleeping, you understand how important ventilation of bedroom is. If alert function turned ON, notification comes to smartphone in dangerous waters.

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The Traffic Light

If looking at value is troublesome, just look at lamp color. Green (Good), Yellow (Caution), Red (Danger). Same as traffic light. If it turns red, no matter how cold/hot, please open window. Moment fresh air comes in, you should feel fog of brain clearing.

2. The Silent Giant: Dyson Purifier Big+Quiet

Sound of air purifier (Go-o sound) chips away concentration. Dyson’s new work is “Quiet” as name suggests. Air volume is tremendous even at low rotation, circulates air even in room of about 100 tatami mats.

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Dyson Purifier Big+Quiet

HEPA filter life is long as 5 years. Thinking of running cost, actually cheap. Design is beautiful, becomes object of room.

Amazon

3. Comparison: Measure or Purify

項目 Aranet4 Home Dyson Purifier
Function Measurement only (CO2/Temp/Humid) Purification + Measurement
CO2 Accuracy Very High (NDIR) Normal
Portability Can carry Huge
Solution Urge ventilation Clean air

4. The Invisible Enemy

Besides CO2, there are enemies. VOC (Volatile Organic Compounds) and PM2.5. Trace chemical substances are coming out from new furniture and paint.

Do not manage these “Somehow”. Please Quantity. If number is visible, countermeasure can be taken. Cannot fight invisible enemy.

Conclusion: Buying Air

Before lamenting “Urban air is dirty”, please look at air in your room. Probably, it is dirtier than outside.

Please place Aranet4. It is compass to clear “Invisible Fog” that lowers your performance.

# co2-monitor # aranet4 # dyson # air-quality # wellness # 2026