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Can You Suffocate In Lectures?


The percentage of air which is carbon dioxide is 0.034 which is 340 parts per million (ppm), if we are outside, the level of CO2 stays around this level unless you are near a chimney, fire or anything which is burning and hence producing CO2. However if you are inside the level of CO2 will begin to accumulate especially if there is no ventilation. The critical point at which the level of CO2 becomes dangerous is around 5000 ppm or approximately when there is 0.5% of CO2 in the air.

The rate of the CO2 increasing can be measured by recording the CO2 level at different times and plotting a graph of CO2 against time. In this experiment we have recorded the level of CO2 at various time intervals during lectures and observed the affects when windows are open, closed and opened half way through the lecture. Also we have worked out the time spent in the room before the critical level of 5000 ppm is reached on condition no one leaves or enters the room and the doors and windows remain as they were.



Using the carbon dioxide meter the level of CO2 in the lecture was monitored by recording the level at points during the lecture and then plotting a graph. From the graphs the linear trend line was plotted and the rate of the increase of CO2 was obtained from the gradient. The time taken to reach the critical point was calculated from the formula of the trend line for the given room and day, hence taking into account the initial level of CO2 before the lecture started.



From the graphs for P114 and by comparing the gradients for different rooms as in the table opposite we discovered that by having with windows open the rate is on average halved. This means it takes a longer time to reach the critical CO2 level with the windows open. The results in the table show that on average the time taken to reach the critical level is two and a half times longer if the windows are open compared to having the windows closed.

From the graphs when a window was opened during the lecture it can be seen that the rate of CO2 before the window is opened is higher than the rate after the window is opened. This also shows that opening a window will not decrease level of CO2 but it will just tend to level off where it is or still increase but a lot slower instead.

Also on average the maximum value of CO2 reached was around 1200 for windows open and 1600 ppm for windows closed which is about 3 times and 5 times greater than the normal outside level (340 ppm) respectively.


Errors and Discussion of Errors

The main errors in this experiments were due to the following things: