Air Quality Meter Tutorial

by Zachary Lee September 16, 2019

Air Quality Meter Tutorial

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Have you ever wondered how to measure the quality of the air around you? With air pollution reaching unprecedented levels, it is critical to understand the amount of volatile organic compounds (VOCs) in your environment using the new Temperature, Pressure, Humidity, and VOC Whisker!


MATERIALS

HARDWARE: 

SOFTWARE:


    What are volatile organic compounds?

    In chemistry, volatility represents how quickly a given substance evaporates. So, volatile organic compounds are carbon-based compounds that evaporate very rapidly and can easily build up into smog clouds. Some of them are perfectly safe, but overexposure to many others has been linked to increased rates of allergies, respiratory disease, and various cancers. 

    Some of the most dangerous include:

    • Benzene is commonly found in gasoline, cigarettes, and paint and is classified as a known human carcinogen by the CDC. 
    • Formaldehyde is found in many glues, resins, foams, plywood, and cigarettes. It has been linked to brain cancer, leukemia, and is the seventh most common allergen. 
    • Styrene may smell sweet, but don't let that fool you! It is a known neurotoxin and carcinogen found in many plastics, though it is especially concentrated in Styrofoam. 

    While the technology to measure each VOC individually is currently in the developmental phases, it is quite possible to measure the total quantity of VOC's in the environment. Let's get started!


    Step 1: Be aware of the burn-in period

    Due to the fact that VOC's tend to be a very small percentage of the air's composition, there is considerable variance in their concentration depending on your location.

    Luckily, the code for this project calibrates the sensor for you! When you first start the sketch, the processor will work to establish the correct baseline for your area. While a fairly accurate air quality reading is displayed right away, the code will progressively adjust the scale over the next 18 hours in order to reach the peak accuracy. 

    If you wish to customize the burn-in period you can do so by opening AirQualityIndex.ino in your favorite text editor and modifying the RANGE_DURATION constant, as shown below:

    const int RANGE_DURATION = 18; // 50% of the VOC portion of the air quality reading will be based on the difference between the current value and the extremes of the last RANGE_DURATION hours

      Step 2: Uploading the Code

      • If this is your first time using TinyCircuits products, please refer to the TinyScreen+ Setup Tutorial to configure the Arduino IDE correctly.
      • Connect the Whisker Adapter TinyShield to the TinyScreen+.
      • Connect the VOC whisker to port 0 on the Whisker Adapter TinyShield via a Whisker cable:

      • Open AirQualityIndex.ino in the Arduino IDE if you haven't already done so in step 1.
      • Make sure that you have the correct port selected. The correct port number will vary, but your processor should appear to the right:

      • Then, upload the code!

      Once you have uploaded your code, the TinyScreen+ should begin displaying the air quality using a graphical progress bar!

      Here are some fun experiments we tried with the VOC sensor along with our results. We encourage you to explore your area and see what you find!

      1. Is air quality higher indoors or outdoors? For us, the air quality was about 75% inside and 80% on the roof of our building. 
      2. Is the air from your air conditioner higher quality than the rest of the room? For us, it was about 10% higher.
      3. If you blow on the VOC sensor, will the air quality go up or down? In our experience, it goes down rapidly, often below 40%
      4. What is the air quality on the corner of a busy city intersection? Quite low, around 65%. Most likely due to the benzene from vehicle exhaust. 

      CONTACT US

      As always, if you have any questions or feedback, feel free to email us at info@tinycircuits.com. We would love to hear any ideas for improvement or new projects you were inspired to work on! 

      Show us what you make by tagging @TinyCircuits on Instagram, Twitter, or Facebook so we can feature it!

      Thanks for making with us!!

       



      Zachary Lee
      Zachary Lee

      Author



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