According to the EPA (Environmental Protection Agency), older school buses can lead to significant health risks for students who typically ride for one to two hours a day. Children are more susceptible to air pollution than healthy adults because their respiratory systems are still developing and have faster breathing rates. In a school bus, students inhale 40 toxic pollutants, some of which are known carcinogens. Exposure to diesel particulate matter can cause premature death, chronic heart and lung disease, and asthma. Studies have shown that exposure to diesel decreases cognitive ability, even after a brief exposure, and affects students’ test scores. Our goal with creating GreenVent is to create an energy-efficient product that will increase circulation so that school buses are safer for students’ health as well as increase awareness by having easily accessible data about what’s in the air.

Problem Statement

School buses can pose significant health risks to students who ride them for a few hours daily, due to inhaling diesel particulate matter, which includes up to 40 toxic pollutants. GreenVent aims to develop a retrofittable, low-maintenance, solar-powered air purifier that detects and filters harmful diesel exhaust gases inside a school bus. This solution enhances air circulation, making school buses safer for students’ health, while raising awareness of the air quality.

Design Alternatives and Ranking

When brainstorming ideas in an attempt to improve the air quality of school buses, we came up with a few solutions:


1. Fan: 

First, we considered implementing a fan to take in fresh air from outside and circulate it around the bus. Though this would decrease the concentration of the PM 2.5 particles, we realized that a fan alone would not eliminate it as we need.


2. Electrostatic Purifier:

Then we thought of adding an electrostatic purifier, in which we would create a device that uses electrical charges to remove airborne particles and pollutants from the air. But, this would be very expensive and high maintenance.


3. Baghouse Filter:

Next, we examined baghouse filters, which capture particulate matter on the surface of fabric filter bags, made of materials like woven or felted fabrics, and trap harmful particles. However, this was very high maintenance and took up a lot of space.


4. Purifier:

Then we considered a purifier that would filter out the PM 2.5, but soon realized that it wouldn’t produce enough circulation throughout the bus.


5. 💡Solar-Powered Fan with Filter

Finally, we came up with the idea of taking a fan and adding a filter that would specifically filter PM 2.5, which would effectively eliminate the harmful particles and efficiency circulate the clean air around the bus. Additionally, we wanted to make it solar-powered so that it would be renewable.


Design Criteria and Objectives

Must Haves:

  • Filters eliminate particulate matter 2.5 (PM 2.5)
  • Sensors detect toxic pollutants
    • flammable gas, smoke, methane, carbon monoxide
  • Data displayed on app
    • App-enabled sensing
    • Bluetooth connected
  • Easily replaceable, low maintenance  
  • Energy Efficient 
    • Solar powered
    • Vibration activated

Initial research for product

designs using Chat GPT

Using the laser cutter on

acrylic for the monitor box

Design Evolution: Monitor

For the monitor we were able to create a breadboard that has a smoke gas, combustible gas, and carbon monoxide sensor. The whole system runs on a lithium ion battery that is charged by solar. We also added a bluetooth monitor to collect data asynchronously. We laser cut acrylic to make the box and added holes on the sides for ventilation. We also added a 5 volt fan to the back of the box so that there would be more airflow.  

Design Evolution: Vibration Activated

Because we want our product to save energy, we decided that our fans should manually turn off when not in use. This vibration sensor is hooked up to the fan’s power supply and when bus vibration is sensed, voltage is sent to the fans. By utilizing a voltage regulator and a transistor, we’re able to power both the vibration sensor and the fans with the same solar panels. Our product will run when the bus is moving, and stop without the driver having to worry about turning off a switch.

Design Evolution: Fan-Filter

Our first prototype was a laptop fan with a cut-up HEPA filter attached to the back using masking tape. We were able to charge the fan with a 5-volt solar panel. After that initial design, we decided to enhance air circulation by adding a larger 12-volt fan and using 12-volt solar panels. Additionally, we included a standard 10x10x1 HEPA filter, readily available at local hardware stores, to ensure easy maintenance of the product. A significant aspect of our goal is to create a climate-friendly product. The vibration sensor integrated into the system enables the product to turn on whenever the bus is in motion, thus conserving energy. Overall, the system is charged by a solar panel that can be attached to a window and is connected to a battery. The battery, in turn, is synchronized with the vibration sensor, providing voltage to the fan with the filter.

Design Evolution: App

We developed the GreenVent App using the MIT App Inventor, which seamlessly connects to our air quality monitors via Bluetooth. The primary purpose of this app is to provide an effortless way to monitor the air quality inside the bus. Additionally, it keeps track of the filter change dates for the air quality monitors.

Key features of the GreenVent App:


1. Real-time Air Quality Monitoring: The app receives data from our air quality monitors and automatically updates the air quality values every 5 seconds. Users can easily view the current air quality conditions inside the bus through the app’s intuitive interface.


2. Filter Change Date Tracking: The app allows users to keep track of filter change dates for the air quality monitors. This helps in maintaining the accuracy and efficiency of the monitoring system. When users change a filter, they can click the “Changed Filter” button to update the display with the last filter change date.


3. Bluetooth Connectivity: The GreenVent App establishes a reliable Bluetooth connection with the air quality monitors, ensuring seamless and continuous data transmission between the monitors and the app.


4. Website Integration: For more comprehensive information about air quality and related services, the app includes a dedicated button that connects users to our website. This provides access to additional resources and details that can further enhance their understanding of air quality concerns.


Overall, the GreenVent App offers a user-friendly and convenient solution for monitoring air quality in buses. With real-time updates, filter change tracking, and easy access to supplementary information, the app aims to contribute to better air quality awareness and management.

Final Product

Testing Results

We used our monitor to take initial data on the air quality and PM 2.5 confluence of an NCSSM diesel-powered school bus (without our product). This allowed us to see what kids are normally breathing.


We found that the air quality was terrible and very high in pollutants.


We then used our monitor on a car and compared the data to see which one was worse. 


Here were the results:

The first two spikes are from the car. The third spike is from the bus. With both, we took this data with our monitor inside of each vehicle and in front of the exhaust.



As you can see, the air quality around the bus was significantly worse than that from around the car.


We went back to the bus and tested the air quality again, but this time with our product in place. We found that there was a slight improvement in the quality, compared to our before data. After doing some calculations, we found that having a larger fan and filter would create more circulation and have more of a significant impact.

AI Usage

AI played a small role in assisting us during the ideation phase. We leveraged AI language models like GPT-3 to generate alternative ideas based on the problem statement and the insights we gathered. We fed the AI model with prompts and questions related to improving air quality in school buses, and it generated a wide range of potential solutions and approaches.

Project Video

Future Work

  • Add a PM2.5 specific sensor to monitor
  • Connect monitor to solar panel
  • Creating more of product to be more efficient
    • Larger fan and filter

Some Sources

  • Projecthub.arduino.cc
  • Aranacorp.com
  • Thezhut.com
  • Ehhi.org
  • Ncbi.nlm.nih.gov
  • Docs.arduino.cc

Meet the Team

Alana Daily


Eisley Jantz

Riverside HS ’25

Dharma ChariLetts East Chapel Hill HS ’25 

Yaqi Li


Hi, I’m Alana! As a kid, I have always loved math. It wasn’t until my very first physics class in high school that I realized how much applying math to practical applications excites me. Along with this, I enjoy creative thinking and coming up with new and innovative solutions. Last year was my first time designing a product related to human health, in which I came up with a fun device that detects radon poisoning. Even before then, I have always been intrigued by mechanical engineering and the design process that goes along with it. GreenVent has been an amazing learning opportunity for me and I hope to engineer many more solutions to societal issues.

I’m Eisley, and I got into engineering in middle school when designing breadboards. I found that I love to build designs and found myself making contraptions from hot glue and cardboard all throughout seventh and eighth grade. I learned to code at the beginning of high school and applied that to more hands-on engineering to produce projects for school. In the future I hope to get similar opportunities to GreenVent as I had such a fun time designing and working on this with the team. 

Hi! My name is Dharma, and I am an avid builder. My interest in engineering started with FIRST Robotics. I have helped craft four robots, specializing in mechanical systems. I am also working on a mini-battle bot for a separate competition.


In addition to mechanical engineering, I am also interested in aerospace engineering. I did orbital mechanics and flight simulators in my aerospace engineering class and made a balsa wood glider and a single-fueled rocket. I founded a rocketry team at my high school, and we will compete in the American Rocketry Competition. I immensely enjoyed creating the GreenVent and look forward to future engineering endeavors.

Hi! My name is Yaqi and I am a rising senior at NCSSM Durham. I was introduced to engineering by Dr.Jefferies, my instructor for Biomedical Engineering, in my junior year. My my motivation  in engineering is to design products that could improve human health. Besides academics, I enjoy playing piano and golf.