Candidate Name: Isabel Alfonso Sifontes Centre Name: Greengates School, Mexico

Candidate name: Isabel Alfonso Sifontes Centre name: Greengates School, Mexico Candidate number: 000396-0001 Centre number: 000396 Internal Assessment

Aim: To investigate how do tropospheric ozone levels in a suburban area located in Huixquilucan, Mexico differ using monitoring of traffic levels and tropospheric ozone strips?

Hypothesis: As a hypothesis, we can say that there will be a higher tropospheric ozone layer in the areas where there are more cars, as showed in Figure 1. 45% of the anthropogenic volatile organic compounds come from motor vehicles, this is because there are some hydrocarbons which do not get burned in your engine and pass through the exhaust unchanged, as this happens, Carbon Monoxide is also produced (CO),1 causing the ozone layer to form in the troposphere.

We might not find a high ozone levels in the strips because of we are doing it in September. The high ozone season in Mexico is from February to June. However, we should be able to see some change between the different areas within my Residential located in Huixquilucan. These areas are: the parking lot, outside the residential, inside a tunnel, post in a roundabout, and at the entrance of the residential. I will have a control area which will the kitchen in my house, this way, I will be able to compare the results from an area that doesn't have any pollution around it.

Figure 1.

Background:

Ozone (O3) is a gas that can form and react under the action of light and that is present in two layers of the atmosphere. High up in the atmosphere, ozone forms a layer that shields

1 "ABD - The facts about car exhausts." 10 Sep. 2015 1 Candidate name: Isabel Alfonso Sifontes Centre name: Greengates School, Mexico Candidate number: 000396-0001 Centre number: 000396 the Earth from ultraviolet rays. However, at ground level, ozone is considered a major air pollutant.2 Ozone is caused by burning fuels, some of the effects include, irritation of the eyes, damage of crops and forests and breathing difficulties.

We are doing this experiment because we live in Mexico City, which has high ozone layer. In our school, we have these “Red flags days” in which we aren’t allowed to do any exercise outside. These “Red Flag Days” are decided using the following website http://www.aire.df.gob.mx When the UV levels reach purple, or if the pollution levels are getting to “bad” then the Red Flag Day is compulsary. This has lead me to investigate about the ozone levels in my residential area, located in Interlomas,

Variables:

Experimental Named variable Units (if applicable) Equipment or variable method to measure Dependent Tropospheric Ozone Schonbein number Using ozone strips level (parts per billion)

Traffic level Number of cars Having a systematic sample Independent The area 5 different places in my residential located in Huixquilucan, Mexico City Control Time in which the 8 Hours A stopwatch ozone strips were exposed 2 "Scientific Facts on Air Pollution Ozone - GreenFacts." 2008. 27 Aug. 2015

2 Candidate name: Isabel Alfonso Sifontes Centre name: Greengates School, Mexico Candidate number: 000396-0001 Centre number: 000396

Time of counting 15 Minutes Using a stopwatch cars Cornstarch and 5 Grams for Dip the strips for 5 potassium iodine on cornstarch and 1 seconds each strip which are gram of potassium all going to be iodine dipped in the same solution.

Materials -Potassium iodine (1g) -Cornstarch (5g) -Beaker (50 mL) -Plastic pipette -Clean empty test tube -Distilled water -Scissors -Ruler -Pencil -Typing paper

Method of the making of strips (The method of making the strips were prepared by the technicians of the school) 1. Place dots at one centimeter intervals on a paper. This is the width we will make the strips. Measure out 5 dots (10 centimeters) for 5 strips. 2. Measure 12 centimeters from the bottom of the sheet and draw a line across the paper.

Again, mark along that line at one centimeter intervals. 3. These drawing lines are guides for cutting out the strips 4. Place 100ml of distilled water into a 250ml beaker. Stir in 5g of cornstarch 5. Place the beaker on a hotplate over low heat and stir till the contents are transparent 6. Remove from the hotplate and stir in 1g of potassium iodide. Cool the solution 7. Dip your paper strips into the solution. Allow the strip to stay in solution for about five seconds before removing. 8. Lay the wet strip on a piece of paper, paper towel, or cloth. Let it dry 9. Let them dry, which shouldn’t take long, maybe 20 minutes. To preserve them, place them in a ziploc bag. 10. At this point where all the strips have been dipped, take a picture of them. 11. Make sure to repeat steps 1 to 10, 5 more times to be able to have 25 strips.

Method of experiment 1. Use this website to know the humidity level of the day and record it, http://www.aire.df.gob.mx/default.php (This is your secondary data) 2. Place the strips in the areas where you have decided to measure the tropospheric ozone level and take a picture of them (make sure this is in the morning so that you can do step 6 with no problem) Remember to record the time in which you place the strips

Area Perceived levels of traffic in a scale from 1 to 10 (10 being the highest and 1 being the lowest) Kitchen (control) 1 Parking lot 3 Outside the residential 4 In a tunnel 2 Post in a roundabout 8 Entrance of the residential 10

3. Place 3 strips in each area to have enough trials using tape 4. Record the number of cars that pass through the area during 15 minutes 5. Repeat steps 2-4 in the different areas that you have chosen. 6. Go back to each area after 8 hours and place the strings in ziploc bags with labels of the areas in it. 7. Take photographs of the strips after you collect them PLEASE NOTE: In step 3, place 5 strips instead of 3 strips. This will help you to get more data and therefore have more reliable results

Data collection

“Table showing the humidity, the times of when the strips were placed and removed, the number of cars recorded during 15 minutes, the total time the strips were exposed and observations in each area”

Area Humidity Time the The Time the Total time Observations (%) strips number strips exposed were of cars were in area placed recorded removed (Hours/mi (hours/mi during 10 (hours/mi nutes) nutes) minutes nutes) (am) (pm) Kitchen 74 10:20 - 6:50 8:30 -Location under (control) a roof with small exposure to sunlight Parking lot 74 10:06 4 6:48 8:42 -Location under a roof with small exposure to sunlight Outside the 74 9:54 2 6:45 9:31 -Large residential exposure to sunlight, green area around Post in a 74 9:15 20 6:43 9:28 -Some roundabout exposure to sunlight, some green area around In a tunnel 74 9:26 10 6:41 9:15 -Some exposure to sunlight, average green area around Entrance of 74 9:40 27 6:37 9.37 -Convenience the stores and a lot residential of green area

“Table showing visual results of the experiment”

Area Area surrounding the strip Strips before exposure Strips after exposure Kitchen (control)

Parking lot

Outside the residential

In a tunnel

Post in a roundabout

Entrance of the residential

“Table showing the Average Schönbein Number for each area”

Area Schönbein Number

Strip 1 Strip 2 Strip 3 Average

Kitchen 1.0 1.0 1.1 1.0 Parking lot 3.4 3.2 3.0 3.2 Outside the residential 1.0 1.2 1.0 1.1 In a tunnel 5.8 5.0 5.4 5.4 Post in a roundabout 7.0 4.0 6.5 5.8 Entrance of the 5.7 5.0 4.8 5.1 residential

“Table Showing the Average Ozone Level for each Area” Area

Ozone level ppb (parts per billion)

Strip 1 Strip 2 Strip 3 Average

Kitchen 8.0 8.0 9.0 8.3 Parking lot 32.0 30.0 29.0 30.3 Outside the residential 8.0 9.2 8.0 8.4 In a tunnel 71.0 54.0 59.0 61.3 Post in a roundabout 80.0 39.0 79.0 66.0

Entrance of the 61.0 54.0 49.0 58.0 residential Figure 2.

This bar graph shows the number of car recorded during 10 minutes for each location. We can see that the Entrance of the residential is the area with the highest number of cars with 27 cars. Kitchen has 0 because we are using this area as a control. The range between entrance of the residential and outside the residential is 25 cars.

Figure 3.

This bar graph shows that the highest average ozone level is in the post in a roundabout with 66.0 ppb and the lowest average ozone level is in the kitchen which is the control area with 8.3 ppb

“Table showing a comparison between the Average Schönbein Number and the number of cars recorded in each area during 15 minutes”

Area Average Ozone Level The number of cars (PPB) recorded during 15 minutes Kitchen 8.3 -

Parking lot 30.3 4.0 Outside the residential 8.4 2.0 In a tunnel 61.3 10.0 Post in a roundabout 66.0 20.0 Entrance of the residential 58.0 27.0

Figure 4.

This scatter graph shows the relationship between the number of cars recorded during 10 minutes and the average Ozone Level (PPB). We can see that there is a positive correlation between these two variables.

10 Candidate name: Isabel Alfonso Sifontes Centre name: Greengates School, Mexico Candidate number: 000396-0001 Centre number: 000396 Analysis: Using the data gathered we can see in Figure 4 the graph showing the relationship between the number of cars recorded during 10 minutes and the ozone level (ppb) and how there is a positive correlation between these two variables. As the number of cars increases, the ozone level increases. This can be explained because of the combustion of the fossil fuel from the cars, leading to emit gasses that can increase the level of pollution. Car emissions have few chlorine- or bromine-heavy substances3, therefore the effect on the ozone depletion is not that big, however, if there is a big amount of cars, then the emissions get accumulated and create a big impact on ozone depletion. This confirms my hypothesis of having a higher level of ozone when the amount of cars is higher. However, we can see an anomaly in this graph; the highest number of cars is 27, and the ozone level was 58 ppb when the highest ozone level was 66 ppb with a number of 20 cars. This could have been caused because of the the different amount of sunlight in the area or because of the type of cars that passed next to the ozone strips, they could have been big cars that emit a large amount of gasses or small cars that emit a very small amount. Also, the number of cars recorded in the tunnel was 10, and the ozone level was 61.3 ppb, this could have been caused because of the accumulation of the gasses within the tunnel, making less cars have a greater impact because it’s a closed area. We are able to answer our research question by saying that as the traffic level increases, the tropospheric ozone levels in a suburban area located in Huixquilucan, Mexico increase as well. Mexico City has the condition of thermal inversion which can have been the cause of the large amount of pollution. Thermal inversion is (as shown in Fig. 5 ) when the dry air from the upper layer moves downwards on the lower layer, this trapps the pollution and causes a decrease on visibility. 4 However, the results from the tropospheric ozone levels agree with my hypothesis of not having a large change but a small one because of the time of the year; when not a lot of pollution is taking place.

Figure 5.

3 "How Does Car Pollution Affect the Environment & Ozone ..." 2013. 6 Oct. 2015 4 "Air Pollution in Mexico City - Mexico City Vibes." 2014. 7 Oct. 2015

11 Candidate name: Isabel Alfonso Sifontes Centre name: Greengates School, Mexico Candidate number: 000396-0001 Centre number: 000396 Conclusion: Overall, my investigation has confirmed that as the traffic level increases, there will be a higher tropospheric ozone level in a suburban area located in Huixquilucan, Mexico and viceversa. This is because of the gasses emitted by the vehicles which contribute into creating more pollution. My results have supported my hypothesis, however, there have been other factors which have contributed into reaching this conclusion, such as sunlight exposure.

Evaluation:

Problem Effect on the investigation Solution The high ozone season of The ozone strips may have a To make the investigation Mexico is from February to very small change rather during the high ozone June; the investigation was than a bigger one season. made in September Not having enough ozone Less accuracy and reliability To order more materials in strips for 5 trials in each on the results order to be able to have 5 area trials in each area The time spent to record Lost in reliability because of To change the time spent to the amount of cars was only the missed information record the amount of cars of 10 min, missing mayor during the 8 hours of to at least 1 hour; also take variations over time exposure of the ozone strips in count the type of vehicle To record the Schönbein Less accuracy on the results To measure the percentage Number was subjective coverage of each strip instead of doing a subjective judgement, to ask to several people to make the judgement or to use a colorimeter to measure the color of the strips

The data gathered was enough to address the research question, however one of the problems with the method is that it doesn't specifies where exactly to place the ozone strips, it should have specified whether the strips should have been in a place with exposure to sunlight or to what length away from the street (if there was any), however this would have been really hard, almost impossible to achieve.

Bibliography: Figure 1. http://science-edu.larc.nasa.gov/ozonegarden/ozone.php

Schönbein number: http://www.chemistryland.com/CHM107Lab/Exp03_DetectOzone/OzoneLab/OzoneLab.ht m

Figure 5. http://www.mexicocityvibes.com/air-pollution-in-mexico-city/