Breathe Easy By Chanum Torres A study on the levels of CO2 in vehicle cabins. Redeemer Baptist School Year 10 2014 Table of Contents ABSTRACT 3 INTRODUCTION 4 BACKGROUND RESEARCH 5 THE BUILDUP 5 RECIRCULATION VS. VENTS 5 THE HUMAN EFFECT 6 SYDNEY BUSES 6 AIM 7 HYPOTHESIS 8 CONSIDERING APPROACHES 10 RISK ASSESSMENT 10 METHODOLOGY 11 VARIABLES 12 INDEPENDENT VARIABLES 12 DEPENDENT VARIABLES 12 CONTROLLED VARIABLES 12 APPARATUS 12 RESULTS 14 RISES 15 FALLS 18 EXAMPLES 21 ANALYSIS 25 DIFFERENCE FROM THE STARTING POINT 28 FINDING AN EQUATION 29 RISES EQUATION 30 FALLS EQUATION 32 DISCUSSION 34 AN EXHAUSTIVE EXPERIMENT- FURTHER RESEARCH? 34 THE EQUATIONS 35 CONCLUSION 36 APPLICATION 37 THE WORKING MODEL 37 ACKNOWLEDGEMENTS 38 BREATHE EASY 2 2014 Abstract Breathe Easy is a scientific investigation on the levels of CO2 within vehicle cabins. Spanning several months, the research looked into the extent of CO2 buildup and looked at a primary factor to this said buildup. Gathering data and reaching conclusions involved observing and analyzing dozens of ‘logs’ or graphs generated form data automatically collected by a data logger. Conclusions were reached primarily through mathematical processes, yielding figures that served as evidence for hypothesized points. The main finding was that the number of passengers directly affects the level of CO2 reached in the vehicle cabin. The buildup of CO2 also occurs primarily when the A/C is set to recirculation, as the same air is cycled throughout the cabin. From the results gathered, two equations (one for the rise of CO2 and one for the fall) were generated and give a rough idea of what levels CO2 will be reached provided the number of passengers and duration is known. For example substituting the values 2 for the number of people, 4 (minutes) for the duration into the rise equation, it can be seen that a level of ppm >1000ppm is already reached. With 2 people in 2 minutes, CO2 can be expected to drop by 1000ppm. As fresh air is constantly being brought in under ventilation, levels of CO2 that could pose a negative impact on human health are not reached .The equations are not definitive but communicate the connection established between time, the number of people and the levels of CO2. An automatic cycle has been found to be present in cars. This cycle involves the A/C starting on recirculation, running as so for a period of time then automatically switching to ventilation, resulting in a drop of CO2. This cycle has been found to be insufficient in maintaining good air quality as levels of up to 8000ppm had been recorded. This project uses the ASHARE standards as a reference point for what CO2 levels are recommendable, unsafe etc. and how these levels may impact a human .This report details the genesis of this project, the processes undertaken before and during the data gathering, the results, conclusions, real-world applicability and future direction. BREATHE EASY 3 2014 Introduction My first exposure to the term “ppm” or parts per million was on the National Geographic website. I came across an article on a warming Earth and higher levels of Carbon Dioxide, 400 parts per million, in the air. At the time I was searching for inspiration, inspiration for a topic I could perform a Science Project on. In 2007, I was the Primary Winner in Australia for my research on air quality in my local area. Naturally, I was drawing on ideas from the past to assist me in the present. I was fairly certain an environmental-related project was the way to go, especially in relation to the air. CO2 is indeed a problem on a global scale but so much research had been done on this. I was looking for something that was a problem in everyday life, something practical, applicable and something not given much thought. I started to read about CO2 and its buildup in indoor environments. Mentioned in several studies were the health side-effects brought about by exposure to higher levels of CO2. The Air Conditioning was a major factor in the buildup of CO2 in indoor spaces. Many articles actually defined acceptable and dangerous levels in terms of ‘ppm’. I had not realised the impact the level of CO2 in air we breathe could have on immediate health. I had never seen it as a problem, an issue to be addressed. At this time, the holiday season was starting and traditionally, the number of road accidents spike at this time of the year. Driver fatigue is often to blame for the wrecks left on the side of the freeways. Fatigue, nausea, headaches were all brought on by high levels of CO2. I connected the dots, the different strands of thought in my mind and an idea was born. Was not a car cabin an indoor environment as well? Don’t cars have Air Conditioning? Could the CO2 buildup in cars be at a level that could affect the driver? People I discussed this with at first were skeptical. They said that cars were designed to bring in adequate amounts of fresh air. Dangerous levels of CO2 would not be reached. Well, there was only one way to find out… And so the research began… BREATHE EASY 4 2014 Background Research The Buildup The articles I read concerning the buildup of CO2 were predominately looking at office spaces, classrooms and work spaces. 1There have been standards established, outlining echelons of CO2 ppm and their respective effects on health by ASHRAE ( American Society of Heating, Refrigerating, Air Conditioning Engineers), a reputable society whose work is trusted and referred to by organisations globally2. It is generally accepted that a level <1000ppm is normal, hence ‘safe’. Levels between 1000ppm and 2500ppm bring on general drowsiness. On the roads, a split second of being unfocused could have dire consequences. Levels of 2500ppm-5000ppm bring on adverse health affects such as nausea and headaches. Levels above 5000ppm are highly dangerous and exposure to these levels should not be prolonged. In indoor environments this buildup has been observed, one study even showing that it could be affecting cognitive ability3.This buildup has been established to be active in indoor spaces, consequently, this would hold true for vehicle cabins. They too are indoor environments: sealed, air-conditioned and have people within them. The standards would apply here as well. There were a number of scientific research papers I read that had looked into this buildup of CO2 in vehicle cabins. Two articles, one a research paper summary another an information bulletin page , directly applied to what I intended to do and I was extremely interested by what they had to conclude.4 5 Both stated that increased levels of CO2 had negative effects on occupants including fatigue, micro-sleeps, acidosis and reduced concentration. All these have the potential to cause a road tragedy. They also attributed the buildup of CO2 to the number of occupants. Recirculation vs. Vents These two settings played an integral part in this project. Using the Ventilation setting in the A/C brings air from outside, cools it down and blows it into the car. Fresh air from outside is constantly being brought in. Recirculation mode however, brings air from outside, cools it down and 1http://www.energy.wsu.edu/Portals/0/Documents/Measuring_CO2_Inside_Buildings-Jan2013.pdf 2ASHRAE Standard 62.1-2013 3(https://www.sciencenews.org/article/elevated-carbon-dioxide-may-impair-reasoning 4http://www.lsmtechnologies.com.au/item.cfm?category_id=2483&site_id=14 5 http://papers.sae.org/2008-01-0829/ BREATHE EASY 5 2014 this volume of air is constantly blown around the car. The vents are shut and so the same air circulates. The Human Effect The air exhaled by humans is composed of several gases, including CO2. The odors given off by humans also contain CO2. These can be called bioeffluents. They have an effect on the CO2 levels: contributing to the buildup of CO2 in an environment. With the A/C on recirculation, replacing the oxygen with CO2 and several passengers in the car also giving off their own CO2, the results could be very interesting. Sydney Buses Buses in Sydney’s Hills District are notorious for being extremely crowded at peak hours. Mr Shane Van Der Vorstenbosch, a director at OnSolution, a company selling air quality monitoring equipment, recently measured levels of CO2 on the said buses. “Mr Van De Vorstenbosch said that higher carbon dioxide levels lead some people to feel fatigued, nauseous, sleepy” and even get headaches. Mr Van De Vorstenbosch recorded levels between 505 ppm and 3500 ppm recently on Hills bus routes to the city, compared to an outdoor reading of between 345 ppm and 585 ppm.”6 The article that this came from in the Daily Telegraph was very relevant to what I intended to research. It directly linked the number of passengers to the levels of CO2. It had been established that there was indeed a buildup of CO2 to levels deemed unsafe in comparison to the ASHARE standards in buses. I commented on the article, outlining research I had already conducted as by the time I read the article in March 2014, my logging was well underway. This article assured me that I was onto something interesting, that my research was valid and applicable. 6 See the full article here: http://www.dailytelegraph.com.au/newslocal/the-hills/crowded- buses-co2-levels-ten-times-higher-than-outside-and-hills-commute-among-worst/story- fngr8i1f-1226847846286?nk=35ee43b350d117ec4e544535c9c1cb00 BREATHE EASY 6 2014 Aim 1. To determine the extent of CO2 buildup within a vehicle’s cabin and how quickly levels of CO2, which could potentially affect the driver primarily as well as passengers ,would be reached.