Table 2: standard error of means
Although it is not normally reliable to calculate the standard error using only two samples, these have been included in order to illustrate that the variation in the readings at sites is less than the variation in the readings between sites. This shows that the site means can be sensibly compared.
Figure 1
series 1 = mould colonies – dish 1
series 2 = bacteria colonies – dish 1
series 3 = mould colonies – dish 2
series 4 = bacteria colonies – dish 2
As we can see in figure 1, there were a far greater number of mould colonies than bacteria colonies in all of the locations.
Figure 2
series 1 = mould colonies – dish 1
series 2 = mould colonies – dish 2
series 3 = average number of mould colonies
Figure 3
series 1 = bacteria colonies – dish 1
series 2 = bacteria colonies – dish 2
series 3 = average number of bacteria colonies
The following table shows the different locations that we tested around the school, the type of floor surface they have, and the number of times they are cleaned per week.
Table 3: results compared to floor surfaces to floor surfaces and cleaning regimes.
Figure 4
Figure 4 shows the number of bacteria colonies found in the dishes, plotted against the number of times per week each of the rooms was cleaned. The line of best fit runs in the direction which would be expected by our hypothesis, that is, there is a negative correlation between the number of times per week the room is cleaned, and the number of bacteria colonies found. However, the correlation is extremely weak (r=-0.073), and no reliable or meaningful predictions could made from these results.
Figure 5
Figure 5 shows the number of mould colonies found in each dish plotted against the number of times per week the room are cleaned. The correlational line of best fit here runs in the opposite direction to that which would be expected from the hypothesis. That is, in this case there is a positive correlation between the number of mould colonies found in the dishes and the number of times per week the room is cleaned. This could be because the rooms which are likely to have the most mould spores present, because of their usage, are the ones which are cleaned more regularly. However, in this graph the correlation is also weak (r=0.195), and is not meaningful.
The average number of mould spores in carpeted rooms was 278.8, and the average number of mould spores in non-carpeted rooms was 447.286. It is clear that the locations with non-carpeted floors had on average a greater number of mould spores present than those with carpeted floors. This runs contrary to our hypothesis, being that we predicted that there would be a higher mould colony count from those locations with carpeted floors. This could be because the rooms which are likely to have a higher mould count, due to their purpose and usage, are likely to be floored with a surface other than carpet in order to try to reduce the mould count.
Cleaning Techniques:
Offices (Mr. Fraser’s office and Mr. McManus’s office):
- The offices are cleaned on a daily basis. They rubbish is picked up, they are dusted, and the floor is vacuumed.
- In Mr. Fraser’s office, the carpet is fairly new. In Mr. McManus’s office, the Carpet is very old.
Classrooms (L8 and M4):
- The classrooms are vacuumed twice a week.
- The rubbish is picked up daily.
Toilets (girls and boys):
- The toilets are cleaned daily.
- A general purpose cleaning product is used for the floors. This product is called HC-9E. It is a spray and wipe floor cleaner, which hospitals also use to clean their equipment.
- A sanitiser is also used for the floors, toilets, and any stains or spills. This product is Chloradiet. It consists of 55g p/l of sodium hypochloride, and 40g p/l of sodium hydroxide. This product cleans, sanitises and kills bugs, bacteria and germs.
Weights room:
- The weights room is cleaned twice a week. It is vacuumed and the rubbish is picked up.
Basketball gym:
- The basketball gym is cleaned three times a week. The general cleaning product is used on the floors, and the rubbish is picked up.
- On Friday afternoons, an auto-scrubber is used to scrub the floors, and a gas buffer is used to shine and polish the floors.
Cafeteria:
- The floor is buffed and mopped daily.
Common room:
- The floor is swept and mopped every second day (two to three times a week).
Pool change rooms:
- The pool change rooms are cleaned every second day with the general purpose cleaner.
Discussion:
One of the hypotheses of this experiment suggested that the rooms with concrete, rubber, tiles or linoleum on the floor would harbour less bacteria and mould spores than those with carpet on the floors. However, from looking at the results, we can see that this is not true. The four rooms with the highest count of mould colonies were the boy’s toilet, the weights room, the cafeteria, and the common room, in that order. All of these rooms have concrete, rubber or linoleum on the floors. The three rooms with the lowest number of mould and bacteria colonies were Mr McManus’s office, M4, and the library, all of which are carpeted. The oval had the lowest score in its number of mould colonies. This is surprising, as it would have been expected to have more as it is outside and cannot be cleaned. This suggests something about the cleanliness of Ivanhoe Grammar School. One of the reasons that the rooms with non-carpeted floors had the highest number of mould and bacteria spores is because those rooms that are not carpeted are usually the room that would get dirtier than others. This is because linoleum, rubber and concrete are easier to clean than carpet. However because these rooms are exposed to the most mould and bacteria, which cannot all be cleaned away, they still show the highest colony count.
The results of the amount of mould and bacteria in a room compared to the number of times per week that the room is cleaned also contradict the hypothesis to an extent. The room with the most mould and bacteria spores, the boy’s toilets, is one of the rooms that is cleaned the most regularly – 5 times a week. However, the room that had the second largest amount of mould and bacteria, the weights room, is only cleaned twice a week, which lends support to the hypothesis as twice a week is one of the fewest amount of times that a room is cleaned. However, the third most mould and bacteria ridden room, the cafeteria, is also cleaned five times a week. The two rooms that harboured the most mould and bacteria spores after these three, the common room and the basketball gym, are both cleaned around two or three times a week, which is not very much. These results do lend support to the hypothesis. Of the three rooms that had the lowest amount of bacteria and mould spores, only one result supports the hypothesis. This is Mr. McManus’s office, which is cleaned five times a week. The two other rooms, M4 and the library, are both cleaned twice a week. An explanation for these results could be similar to that of the results relating to the floor surface. Those rooms which are cleaned the most often are those which are likely to become the dirtiest, and so because cleaning cannot get rid of all the dirt that builds up in them, they still have the highest amount of bacteria and mould spores present.
There is a large discrepancy between the number of mould spores present in the boy’s toilets compared with in the girl’s toilets. An explanation for this could be that there are a lot more boys present at Ivanhoe Grammar School than girls. Therefore, the boy’s toilet would be being used more regularly than the girls, so more mould and bacteria would be brought into the toilets, and grow there.
In all of the rooms that were sampled, there were a lot more moulds present than bacteria. An explanation for this could be that when the cleaners use disinfectant cleaning agents such as Chloradiet, an agent designed to kill bacteria spores but not moulds. Unless an anti-fungicide is used in cleaning, mould spores will not be killed. Only in the basketball gym were there any significant numbers of bacteria spores present. This may be because no anti-bacterial cleaning agent is used in this room, and it is a room in which a lot of bacteria may build up from people’s sweat.
It is also surprising that the control location, the oval, had a relatively small amount of mould spore present compared to rooms in the school. This may be because it is better ventilated than any room. The fact that it is in direct sunlight would also have an effect. Moulds usually like to grow in damp places, and in the middle of the oval it would not usually be very damp. The time of year at which we did the experiment is relevant to these results. The experiment was conducted at the end of summer, so the grass and the surrounding air would have been fairly dry, especially as the experiment was done at the end of a particularly hot and dry week (January 10, 2005).
A further factor could be the type of vacuum cleaners used in the rooms. For many of the rooms the main cleaning technique was simply vacuuming. However, as mould spores are microscopic the type of vacuum cleaners used in the school would be unable to pick them up. The vacuum cleaners are the simple bag filter type, and the mould spoors would simply pass straight through the filter and back into the atmosphere, so while the vacuum cleaners may help in getting rid of small objects on the ground, they do little to help get rid of mould or bacteria spores.
Evaluation:
The aim of this experiment was to test the amount of bacteria and mould spores harboured on different floor surfaces around the school. However, what was not taken into account is that we did not actually put the agar gel onto the floor surface. We were therefore also testing the amount of bacteria and mould in the surrounding atmosphere. The discussion looked at the different cleaning regimes used on different floor surfaces, but these cleaning regimes may have had no effect on the atmosphere of the rooms. Therefore, even if the floors were cleaned thoroughly, the petrie dishes would still pick up spores from the atmosphere, which would distort the results.
The experiment was also conducted towards the end of summer, and at the end of a particularly hot and dry week. This means that there would not have been much moisture present in the air at the time. When air is damp, moisture condenses around particles in the air and they settle on the floor. Consequently, at a dry time, there would have been a greater amount of mould and bacteria spores present in the atmosphere than usual.
Conclusion:
The results of this experiment do not support the hypotheses. That is, we did not find that those surfaces that are made of concrete, tiles, rubber or linoleum harboured fewer bacteria that those which are carpeted. We also did not find that the surfaces which are cleaned more regularly harboured fewer bacteria and mould spores than those cleaned less regularly. What the results did show is that those rooms which are used by the highest number of people, i.e. the boy’s toilets, the weights room and the cafeteria, had the highest amount of bacteria and mould spores present. These are also the rooms that have activities taking place which would lead to more growth of bacteria and mould.