Annex A - Group Engineering Proposal

Names: Claire Tham, Seraphina Chia, Victoria Low, Laviin Gunalan
Class: S2-07
Group Reference: A  

1.    Indicate the type of research that you are adopting:

[ ] Test a hypothesis: Hypothesis-driven research
e.g. Investigation of the anti-bacteria effect of chrysanthemum

[ ] Measure a value: Experimental research (I)
e.g. Determination of the mass of Jupiter using planetary photography

[          ] Measure a function or relationship: Experimental research (II)
e.g. Investigation of the effect of temperature on the growth of crystals

[ ] Construct a model: Theoretical sciences and applied mathematics
e.g. Modeling of the cooling curve of naphthalene

[ ] Observational and exploratory research
e.g. Investigation of the soil quality in School of Science and Technology, Singapore  

[  X  ] Improve a product or process: Industrial and applied research
e.g. Development of a SMART and GREEN energy system for households  

2.    Write a research proposal of your interested topic in the following format:

Title: Development of an Air Quality Sensor and Purifier

A.    Problem being addressed

The air quality in Singapore during the haze season each year becomes extremely bad (PSI was 400+ in the year 2013), which is unhealthy for everyone (BBC News Asia, 2013).


At its worst, the haze problem is so bad that far away buildings can barely be seen. As the air quality is horrible, people are falling sick or developing allergies (Fiona Low, 2010).

Transboundary smoke haze from land and forest fires during the traditional dry period between June and October has been a recurrent feature in the southern ASEAN region in the past few decades. These annual fires are caused mainly by land clearing and “slash and burn” agricultural practices in Indonesia, particularly Sumatra and Kalimantan. In the northern ASEAN region, agricultural burning activities are common during the traditional dry season between December and March can also cause large scale smoke haze at times (Meteorological Service Singapore, 2007).

The air quality during the haze period is measured through the Pollutant Standard Index (PSI). PSI is computed based on a 24-hour average of PM2.5 concentration levels, among other pollutants. During the haze season, PM2.5 is the most dominant pollutant. The monitoring stations in Singapore measure the concentration levels of particulate matter (PM10), fine particulate matter (PM2.5), sulphur dioxide (SO2), nitrogen dioxide (NO2), and carbon monoxide (CO). These six pollutant parameters determine the PSI.  (National Environment Agency, 2014)

The PSI value gives an indication of the air quality as shown: (Meteorological Service Singapore, 2007)

PSI Value
PSI Descriptor
0 - 50
51 - 100
101 - 200
201 - 300
Very Unhealthy
Above 300

Worried about their health, people would want the air in their homes to be cleaner. The first solution they would think of would be to wear a disposable mask. However, disposable masks cannot completely protect a person from the harmful chemicals in the air as there may be leakages (Department of Health, 2011).

Another product which is more effective to solve this problem would be to have an air purifier in the house. However, even if the people have an air purifier in the house, switching on the air purifier for the whole day would consume a lot electricity. Furthermore, the air purifiers that are developed by companies in Singapore do not have air quality sensors equipped, so when the air quality deteriorates, people would need to check websites or the news to know the air quality level during the haze season before turning on their air purifier. And when the air quality becomes better, people also have to manually turn off the air purifier. Turning on and turning off the air purifier is especially tedious if the people are too busy to check the air quality or if they are in a rush, because they would forget that their air purifier is on, thus wasting a lot of electricity.

Is there a way to create an automatic air purifier? Is there a way to make an air purifier more effective in purifying the air? Is there a way to develop an air purifier which is more environmentally friendly? Is there a way to develop an air purifier which uses less electricity? Can we also create and air purifier that is not as bulky as the ones on the market, but also purify the air in a larger area? We aim to find the answers to these questions.

B.    Goals

We aim to find out how arduino works with an air quality sensor and purifier, as well as how the different systems work differently to remove different harmful chemicals or particles in the air. By researching and learning about arduino and the different systems, the collected data will be used to develop an environmentally friendly and effective air quality sensor and purifier to make sure the air in the house will be clean and healthy for residents, especially asthmatic people or people with allergies, to inhale. Thus, the air in the house will be healthier for people to breathe.

With our device, we aim to decrease the carbon monoxide levels from 2000ppm to less than 20ppm of carbon monoxide in the time span of ½ an hour.

Alternative solutions

Design 1 : Water based air purifier

How it works

There is a rotary fan that is attached to the top. When the rotary fan is turned on, it moves the air at a higher speed which decreases the air pressure (Cliff J, 2005) and causes the air to enter the container which is the body of the air purifier. When the air flows through the water, the dirt in the air is collected in the water and then clean air exits the container.

Screen Shot 2014-07-14 at 10.42.29 AM.png

Screen Shot 2014-07-14 at 10.43.02 AM.png

How it is built

Materials needed :
- CD container
- rotary fan
- screws
- vacuum filter

Model : Having flipped the CD container upside down, the cover of the CD container will be replaced with the rotary fan. The rotary fan will be secured with screws. The screws will be secured with bolts to ensure the rotary fan stays in place. There will be slits cut into the sides of the container above water level to let the clean air escape. Water is in the container to collect the dirt. To ensure that the air leaves the container as clean as possible, there are sheets of vacuum filter dryer sheets covering the slits of the container (Hamed . A, 2009).

Design 2 : HEPA filter / Adsorbent (Activated carbon air filter - Charcoal (treated)) /UV light air purifier

How it works

HEPA: It works by forcing air through a fine mesh that traps harmful particles such as pollen, pet dander, dust mites and smoke from cigarettes (WebMD, LLC, 2012). Most of the airborne pathogens which measure more than 0.3 micrometers in length will be removed (Becky Metivier, 2012) .

Absorbents: Most of the absorbents sold in the market are also known as activated carbon air filter which is charcoal which has been processed to absorb more chemicals than unprocessed charcoal (HowStuffWorks, 2000). This filter can absorb fumes, odors and chemicals (Michigan State University Extension, 2003). The activated carbon air filter has to be changed from time to time (Aquariacentral, 2008).

UV Lights: Microorganisms and viruses cannot survive being under the UV lights. Hence, these harmful organisms will be removed from the air before they reach the human nose (Ben Davis, 2014).

Design 3 : Ionic Air filter

How it works

Ionic air filters rely on voltage to charge air molecules. Typically, they produce negatively charged ions, also called anions, which then attract particles in the air, in much the same way as static electricity. As the particles make contact with the anions, they are de-ionized and removed from the air stream. However, this type of air purifier produces ozone which is a potential pollutant and irritant. The devices also don't effectively remove dust, dander and other irritants from a room. Without fans, they can't collect airborne particles from more than a few feet away. And when even small amounts of dust enter the device, the plates inside quickly lose much of their power to attract more particles. Meanwhile, the charged particles that stick to walls or TV screens haven't left the room and can always billow up again to cause trouble (Chris Woolston, 2008).
Materials needed:
- Magnetic Plates
- Ion generator and fan mechanism

Best Solution and Reason :

After much evaluation, we decided that our best design is design 1. This is because the materials are easy to find and the idea is very feasible, it is also very effective in removing air pathogens, it also does not produce pollutants like the ionic air filter (Ben Davis, 2014). However, after deeply thinking through the design again, we decided to combine both designs 1 and 2. This is because the combined designs will be much more effective in removing the different pollutants in the air. It is more effective in the sense that more air can be filtered at once, and the more harmful type of pollutants will also be removed.

Due to safety reasons, the section that will be filled with water should be separated from the electrical components in the air purifying device as the water can cause the wires to short circuit. Because of this, our device will be made of two different boxes, one for the air to enter and pass through the HEPA filter and one for the water based air purification. Since there are two different boxes that the air is supposed to travel through to get purified, we have decided to add an air pump in the first box to lead the air into the second box through air tubes. Within the air pump, there are also additional air filters (Wikipedia 2014). This adds onto the efficiency of our air purifying device.

One thing to take note of for the air pump is that the base of the air pump has to be above water level so as to ensure that the water in the second box will not backflow into the air pump and spoil it (Wikipedia, 2014).

The main changes that are going to be taking place is the adding of the HEPA filter and Totobobo masks. We are also going to remove the UV lights and change the arrangement of the entire system. We added extra filters because we found out that the water-based filter alone will not be able to completely filter the air and get rid of all the pollutants from the haze as water will only be able to remove the dust and dirt (Top Purifier Reviews, 2014). The HEPA filter and Totobobo masks will be able to filter pollutants like PM2.5, which is one of the main pollutants during the haze season.

We decided to remove the UV lights because UV lights are used to kill microorganisms and viruses in the air (Gary Zeman, 2014). The main purpose of our air quality sensor and air purifier system is to purify the air by removing dust particles, dirt particles and the harmful pollutants in the air. Hence, killing microorganisms and viruses are irrelevant in the system and are therefore not included in the final design.

The finalised design works by having the polluted air (different amounts of smoke which contains carbon monoxide) enter the air purifier through the rotary fan. The rotary fan speeds up the rate at which air enters the air purifier and also ensures that the polluted air passes through the system quickly. The air will then pass through the Totobobo mask, which is placed right at the opening where air enters the air purifier. The Totobobo masks acts as a pre-filter and having the polluted air pass through the Totobobo mask first will also ease the other filter’s load of purifying the air. This ensures that larger dirt and dust particles are filtered before the air moves on through the air purifier system whereby smaller pollutants in the air will be filtered out.

In design 1, we used vacuum filter dryer sheets. However, after further research, we found out that vacuum filter dryer sheets can only filter out dust and dirt (Wikihow, 2014). We then decided to replace the vacuum filter dryer sheets with Totobobo masks. Totobobo masks are a type of mask that filters the smallest pollutants up to the size of 0.1 µm (AQICN, 2013). This means that this mask is able to filter out the most dominant pollutant PM2.5 which measures 2.5µm, as well as other pollutants. The Totobobo mask is actually an extra precaution in the air purifier system to ensure that most of the pollutants in the air during the haze period, especially PM2.5, is removed. Hence, ensuring good air quality in the “room” (our testing area).

The first filter we decided to add from design 2 is the HEPA filter. After the air passes through the Totobobo mask, the air will then pass through the HEPA filter. We did some research on the HEPA filter and found out that HEPA filters are able to remove air pathogens larger than 0.3 micrometers (Becky Metivier, 2012). The main pollutants in the air during the haze are particulate matter (PM10), fine particulate matter (PM2.5), sulphur dioxide (SO2), nitrogen dioxide (NO2), and carbon monoxide (CO) (Baker, 2012).
Image showing the size of PM2.5 and PM10

PM10 particles are less than 10µm in diameter and PM2.5 are less than 2.5µm in diameter so the HEPA filter will still be able trap the PM10 and PM2.5 particles, since the HEPA filter can filter particles that have a diameter greater than 0.3 µm.

Sulfur dioxide is a compound made from 1 sulfur atom and 2 oxygen atoms. One sulfur atom is 0.000104 µm in diameter and one oxygen atom is 0.000074 µm in diameter (McClure, 2009). A sulfur dioxide particle is estimated to be about 0.000252 µm in diameter.

Nitrogen dioxide is a compound made from 1 nitrogen atom and 2 oxygen atoms. One nitrogen atom is 0.00015 µm in diameter and one oxygen atom is 0.000074 µm in diameter. A nitrogen dioxide particle is estimated to be about 0.000298 µm in diameter.(Noreen D. Poor ,2000)

Carbon monoxide is a compound made from 1 carbon atom and 1 oxygen atom. One carbon atom is 0.00022 µm in diameter and one oxygen atom is 0.000074 µm in diameter. A carbon monoxide particle is estimated to be about 0.000368 µm in diameter (National Physical Library, 2014).

Since the diameters of sulfur dioxide, nitrogen dioxide and carbon monoxide are lesser than 0.3 µm, none of them will be able to be filtered by the air purifier system. However, this is not a huge problem as the most dominant pollutant during the haze season is PM2.5, and the main priority of the air purifier’s system is to remove the most dominant pollutant.

After passing through the Totobobo masks and HEPA filter, the air will then enter the air pump which will lead the air to the second box. The second box is filled with water that has a water level lower than that of the air pump. This prevents the backflow of water into the air pump (Wikipedia, 2014). The air pump has three main components: the transformer, the magnet and the airbag. When the air pump is turned on, the transformer will have two poles which will cause the magnet to repel and attract, thus causing the magnet to vibrate up and down very quickly and press the airbag that will then pump the air through the tube. Pumps operate by generating pressure differences between intake and outgoing valves (Nick Silcox, 2011). Aeration pumps take advantage of the force air places on water in a tube. As air is pumped into a water tube, the continuous stream of rising bubbles “drags” water along its upward motion (Michael Rosenfield, 2014). This causes a displacement in the water, stirring it and causing any left over dust that has not been filtered out to mix into the water. Aromatics is added to the water so that the air that exits the air purifier system will be nice-smelling. The water-based filter filters the air by removing dirt and dust particles. This means that the water-based filter will have the same function as the Totobobo masks. However, unlike the Totobobo mask, the water-based filter is actually an extra filter which filters dust and dirt particles in case the Totobobo masks and HEPA filter did not manage to filter those particles.

The cleaned air then exits the air purifier system through the opening where the second rotary fan is in place in the second box.

The following is the finalized design for our air purifier system: (This design does not include the air quality sensors and the area where the pollutants will be generated to test our prototype.)

Screen Shot 2014-08-26 at 9.48.44 PM.png

Our design is also incorporated with a carbon monoxide sensor. The carbon monoxide sensor is placed at the location as shown in the experimental setup picture below at the data analysis section.

After further consideration, we have concluded that making the air purifier turn on and off solely according to the readings of the carbon monoxide sensor is too ambitious. Thus, the development of the carbon monoxide sensor is only for the representation of the air quality in the room to test the efficiency of our device.

Our methods of going about doing this project would be to research on the problems faced by people during the haze season, past air purifier projects and products, the different types of filters, the different types of systems, different types of pollutants and chemicals as well as their sizes on the internet and in the national libraries. Then, using the collected data, we will choose from 3 different designs of air purifiers. The 3 designs are water based air purifier, HEPA air filter and Ionic air filter.

We were going to choose design 1 to build. However, after thinking about design 1 again, we decided that it was not very efficient in removing all the harmful pollutants in the air during the haze period. Hence, we decided to combine designs 1 and 2 to ensure that our air purifier is able to remove all the pollutants in the air. Design 3 was not chosen because ionic air filter releases pollutants into the air, which is the opposite of what we want (pollutes the air instead of purifying it).

The carbon monoxide sensor is mainly made with an MQ-7 sensor, which is sensitive to carbon monoxide (Tracy Allen, 2012), and the Arduino Black. Our reason for using a carbon monoxide sensor is because there is carbon monoxide present in the haze as stated in the section of “Problem being addressed”. Thus, we are using carbon monoxide levels to represent air quality in this experiment.

C.    Description in detail of method or procedures

Formulating Hypothesis

Since we are conducting an engineering project, we do not need to formulate a hypothesis or an independent variable since no factor is being changed.

Dependent Variable :
  • The carbon monoxide level in ppm

We can measure the dependent variable by using the MQ7 carbon monoxide sensor that we will develop. We will then record the readings from the MQ7 carbon monoxide sensor that shows up in the computer that it is hooked up to.

Constants :
  • The amount of time allowed for the air purifier to clean the air for each experiment
  • The amount of water in the water based air filter section
  • The type of smoke used

We will ensure that we use a stopwatch to time the whole procedure every time we conduct another experiment so that we can accurately start and stop the device and make sure each experiment lasts for 30 minutes exactly.

We will also draw a line on the box that is used for the water based air filter section to represent the water level so that when we renew the water each time for each experiment, we can follow the marking and ensure that the water level remains constant.

We will accumulate multiple pieces of the same type of paper so that we can burn the same type of paper for all experiments and produce the same type of smoke.

More accurate readings :

In order to make our readings more accurate and to plot a more accurate graph, we will consistently note down the readings read by the carbon monoxide sensor at intervals of 5 minutes from the start to the end of each experiment. We will also conduct a total of 3 experiments and find the average results so that we can plot graphs for all 3 experiments and for the average results to get a more accurate overview of the success of our air purifier.

Equipment List

  • 2X Rotary fans
  • 4X Wire mesh
  • 10X Totobobo Filters
  • 1X HEPA filter
  • 1X Air pump
  • 1X Air pump connector (for air tubes)
  • 1X long strip of air tubes
  • 1X Aromatics
  • 1X Arduino set [black]
  • 1X Small box (Water-based filter)
  • 1X Short metal box (to level the air pump)
  • 1X Roll of Cling Wrap
  • 1X Disposable container for MQ7 carbon monoxide sensor
  • 1X Packet of bluetack
  • 1X Room for experiment
  • 1X Small non-flammable box
  • 1X Large transparent container (for the air purifier system itself)
  • 1X Screws (one packet)
  • 1X Nuts (one packet)
  • 4X Screw driver
  • 4X Penknives
  • 1X Hot glue gun
  • 1X packet of glue sticks
  • 36X pieces of paper
  • 1X roll of duct tape
  • 1X wire stripper
  • 2X 3-pin plug head
  • 1X long strip of insulated wire
  • 2X wire connectors
  • 1X large wooden box


Screen Shot 2014-08-26 at 9.48.44 PM.png


Part 1 - Connection of rotary fan wires

  1. Cut a suitable length of the insulated wire (Long enough to connect from the air purifier system to the 3-pin plug)
  2. Strip both ends of the insulation
  3. Follow the instructions on the paper on top of the plug to connect the individual wires to the pins
  4. Connect the other end of the insulated wires (already stripped) to a wire connector using a screw driver
  5. Strip suitable lengths of wires of the rotary fan
  6. Connect the wires of the rotary fan to the wire connector using a screw driver
  7. For the two rotary fans, we need to connect each of them to a 3 pin plug so that we can supply electricity to them through the socket. To do this, we will get cable wires and trim off a decent length of the insulation rubber on each end. Then we will strip the wires inside the cable wire and connect them to the 3 pin plug according to the arrangement shown below.

  1. After one end of the wire is connected to the 3 pin plug, we will connect the other end to one opening of the wire connecter. The other opening of the wire connecter is where we will connect the wires of the rotary fans. We will repeat all of this twice since we have two rotary fans.

Part 2 - Building the air purifier

  1. Acquire all the necessary equipments (refer to equipment list)
  2. Attach 2 wire meshes to both sides of the rotary fan using bolts and screws
  3. Cut 1 hole at the side of one large transparent container with considerations to the size of the wire meshes and rotary fans.
  4. Create 4 holes for the screws and bolts to screw the rotary fan into place (The size of the holes should be slightly smaller than the size of the screws)
  5. Attach the rotary fan to the large transparent box using screws and bolts
  6. Cut other holes which are necessary (For tubes to go through to the air pump, the hole for the wire of the air pump to reach the socket)
  7. Cut a hole in the piece of cardboard to fit the HEPA filter and ensure that this piece fits the large transparent container. These cardboards are reused from old card boxes which ensures the materials used are more environmentally friendly.
  8. Attach the HEPA filter to the cardboard before attaching the cardboard to the center of the large transparent container. Make sure that it is secure and use hot glue guns to secure the HEPA filter into place. Ensure that there are no leakage of air by using the hot glue guns to cover all holes.
  9. Place a small metal box in the next section. We will use a metal box as it is sturdy, so it can support the weight of the air pump, and it has been reused.
  10. Place the air pump in the next section of the system on top of the metal box.
  11. Connect the wire (leading to the socket) to the socket and ensure that no air escapes that hole by using cardboard to cover the huge hole and hot glue gun and blue tack to secure the cardboards in place and also to ensure no leakage.
  12. Place the 6 tubes from the air pump through the 6 holes created earlier and place them into the green box. Ensure that there are no leakages by making sure that the tubes fit into the holes tightly. (Tight but not till no air can flow through)
  13. Cut 6 holes in the lid of the green box at the side (water based filter) for the six air tubes to go through into the water.
  14. Cut another 4 holes in the green box in considerations to the size of the screws which are going to screw the second rotary fan into place
  15. Cut 1 hole at the in the centre of the green box with considerations to the size of the wire meshes and rotary fans.
  16. Fill the green box with water, ensuring that the water level does not exceed the the height of the base of the air pump. Ensure that the water will not come into contact with the water.
  17. Add aromatics.
  18. Using duct tape, ensure that the entrance of the tube which the air escapes from is under water.
  19. Use the cover of the whole transparent box to cover the whole system in the large transparent box.
  20. Ensure that no air can escape each section of the system and of the whole experimental area (room).

Part 3 - Preparing the Setup

  1. Attach Totobobo masks onto one side of the wire mesh of the first rotary fan
  2. Place the device into the large wooden box
  3. Place paper inside a small unflammable box
  4. Place the small non-flammable box inside the room, ensuring that the flame will not be able to reach the device or any wires
  5. Close all windows and openings of the room so that no smoke will exit the room
  6. Burn the paper until all of it is burnt
  7. Turn on the MQ7 sensor that is hooked up to the laptop
  8. Turn on the air purifying device
  9. Leave the room and close the door
  10. Cover the area between the door and the floor with a wet cloth so that no smoke can escape the room
  11. Note down the readings from the MQ7 for 30 minutes for each experiment

Part 4 - The carbon monoxide sensor

1. The gas sensing layer on the MQ7 is made of Tin dioxide (SnO2), which has lower conductivity in clean air. The conductivity increases as the levels of carbon monoxide rise (Mikro Elektronika, 2014). Because of this, the higher the carbon monoxide level is, the lesser the resistance will be and the smaller the reading of the MQ7 will be.

2. This is the code that we will use to programme the arduino:

float Ro = 10000.0;    // this has to be tuned 10K Ohm
int sensorPin = 0;  // select the input pin for the sensor
int val = 0;        // variable to store the value coming from the sensor
float Vrl = 0.0;
float Rs = 0.0;
float ratio = 0.0;

void setup() {
Serial.begin(9600);      // initialize serial communication with computer
// analogReference(EXTERNAL);

// get CO ppm
float get_CO (float ratio){
 float ppm = 0.0;
 ppm = 37143 * pow (ratio, -4);
return ppm;

void loop() {
val = analogRead(sensorPin);     // read the value from the analog sensor
Serial.println(val);             // send it to the computer (as ASCII digits)

Vrl = val * ( 5.00 / 1024.0  );      // V
Rs = 20000 * ( 5.00 - Vrl) / Vrl ;   // Ohm
ratio =  Rs/Ro;                      
Serial.print ( "Vrl / Rs / ratio:");
Serial.print (Vrl);
Serial.print(" ");
Serial.print (Rs);
Serial.print(" ");
Serial.print ( "CO ppm :");


3. The formula shown below is the formula for linear equations (y = mx + c). The coordinates of the graph below have been plotted in a logarithmic graph. By finding two different points and their coordinates on the graph, we can determine the gradient of the linear graph (m). Once we have determined the m value, we can sub in the y and x coordinates for when the surrounding air has 100PPM of carbon monoxide (1 and 100 respectively) and find the c value. That will lead us to our final equation which is included in the picture below.
Screen Shot 2014-08-24 at 4.48.25 PM.png

4. Ro is 10K ohm as the resistor that we are using is a 10K ohm resistor. Rs is determined by the equation “Rs=20000*(VC-VRL)/VRL”. This equation is included in the code so that the computer can determine the Rs value. VC is the voltage that the MQ7 sensor is receiving which is 5V from the arduino.

5.  VRL is determined by the equation “VRL = val * ( 5.00 / 1024.0 )”. “val” is the value coming from the sensor. This equation is also included in the code so that the VRL value can be subbed into the equation that determines Rs. By using these equations, the computer will help to calculate everything before printing out the PPM value of carbon monoxide levels.

6. The MQ7 carbon monoxide sensor has six pins, two ‘A’ pins, two ‘B’ pins and two ‘H’ pins. The ‘H’ pins are the heaters and connecting a voltage to one of the ‘H’ pins will keep the sensor hot enough to function properly. Connecting five volts at either the ‘A’ or ‘B’ pins causes the sensor to emit an analog voltage on the other pins. A resistive load between the output pins and ground sets the sensitivity of the detector. Below is a circuit diagram of how we will connect the MQ7 sensor to the arduino.

Screen Shot 2014-08-31 at 4.10.58 PM.png

Part 5 - Experiment

  1. Light up the paper in the small non-flammable box
  2. Test the carbon monoxide level in the room using the MQ7 carbon monoxide sensor
  3. Record the reading of the carbon monoxide levels
  4. Turn on the Air purifier
  5. Leave the room and close the door. Cover the area between the door and the floor with a wet cloth so that no smoke can escape the room
  6. Allow the air purifier to purify the air for 30 minutes
  7. Record the readings of the carbon monoxide sensor for that 30 minutes
  8. Repeat steps 1 - 7 for each experiment with different numbers of paper (6, 12 and 18 respectively)
  9. Plot a graph of the change in carbon monoxide levels in the room for each experiment
  10. Draw a conclusion
  11. See if any changes are to be made in the system and improve on the system

• Risk and Safety: Identify any potential risks and safety precautions to be taken.

The potential risks are:
  • We have to produce harmful gases or use chemicals to create an atmosphere to test our prototype. Doing this might harm our health if we accidentally breathe in the harmful gases and pollutants. To protect ourselves from the gases, we can stay a safe distance away from the atmosphere we created so that we will not accidentally breathe in the harmful gases. We may also wear the Totobobo masks to further protect us from the harmful gases. The different types of harmful gases are: PM10, PM2.5, Sulfur Dioxide, Nitrogen Dioxide and Carbon monoxide. Though these gases will not actually kill anyone, they may cause serious health issues if inhaled by people.
  • To see if our prototype is effective, we also have to add dust to our atmosphere. However, some people may have sinus or allergies and the dust created to test our prototype might affect those people. We can prevent this by warning the people who have sinus and allergies, and also have the needed medication for their sinus and allergies on standby. They can also take extra precaution by wearing disposable masks or the more effective Totobobo masks.
  • When the blades of the rotary fan is spinning, we might accidentally cut our own finger, thus when handling the rotary fan, we would not turn on the electricity when we are holding it. There will also be a wire mesh around the perimeter of the rotary fan so that we will not accidentally touch the moving blades.
  • When changing the water in the water-based filter, we might accidentally spill the water on wires. The sockets may be turned on and there might be electricity running through the wires. Hence, the spilled water may cause a short circuit under the condition that the wires are broken. We can ensure that this will not happen by checking the conditions of all the wires before building our air purifier and also take extra caution while changing the water in the water-based filter. We are also separating our main air purifier system from the water based filter so reduce the risk of wires coming into contact with water and short circuiting it.
  • When burning the paper, we may accidentally burn ourselves or set the whole system on fire. Hence, we have to make sure that we have a fire extinguisher at the ready at all times in case the flame goes out of control and causes the whole set up to catch on fire and have a water running tap nearby and a first aid kit in case we get burned.
  • We may accidentally cut ourselves while cutting the holes in the box. We will prevent this by being extra careful while cutting.

D. Bibliography

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Cliff, J. (2005, June 4). What happens to the air pressure when a fan is used. Retrieved September 17, 2014, from

Davis, B. (2014, Mar 1). Ionizers and UV Lights: Potentially Dangerous Tech in Your Air Purifier - TopTenREVIEWS. Retrieved July 10, 2014, from

Department of Health. (2011, Mar ). How to Use a Disposable Respirator. Retrieved September 17, 2014, from

Grabianowski, E. (2014, January 1). How Air Purifiers Work. Retrieved July 10, 2014, from

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