According to above results, there are many issues can be discussed. This section will
separate into environmental conditions and physiological responses to discuss results of this thesis and infer the interaction between environment and human physiology.
4. 1 Effect in environmental conditions
This thesis simulated the un-controlled environment to model the variation of CCO2 and verify some humanity experiments (ventilation rate is 50 cfm=1.415×106 ml/min.). In the section 3.1.2 demonstrates the model of CCO2, and Eq. (5) result the variation of CCO2 when environment with human. To investigate increased situation of CCO2, this thesis demonstrate the increase rapidly period when half of CCO2 growth to steady state, and there are following three statuses to be discussed the required time of increase to steady state. The driving equation and discussion is according to Eq. (5).
y f a0 e b0t c0 when y a0
a0 a0 c0 when a<0 →
(6)
In the normal condition, this study set the a0 is 1200 ppm, b0 is 0.0001, and c0 is 400 ppm, and change these critical values (a0, b0, and c0) to discuss different status. Firstly, when a0 is
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increased to 2000 ppm and b0, c0 fixed. Since the difference between initial CCO2 and maxima CCO2 is increased by different human metabolic rate, CCO2 need more time to increase to steady state (Fig. 17 (a)). Secondly, when b0 is increased to 0.001 and a0, c0 fixed. Exponential character lead CCO2 need more time to reach steady state (Fig. 17 (b)). The third status is c0 increased to 800 ppm and a0, b0 fixed. CCO2 need less time to steady state, since initial CCO2 is high enough and close to steady state.
Fig. 17 Three statuses to be discussed the required time of increase to steady state. (a) a0 is increased to 2000 ppm and b0, c0 fixed, (b) when b0 is increased to 0.001 and a0, c0 fixed, and (c) c0 increased to 800 ppm and a0, b0
fixed.
These discussed results can be used to predict different conditions in the environment clearly. Additionally, the variations of environmental conditions are affected by human metabolism in the room, and it is necessary to verify the performance of predict model by more humanity experiments.
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4. 2 Physiological issues
4. 2. 1 Essential conditions for choice physiological parameters
If environmental conditions changed, hot flashes can be observed easily. Since face is
located in the vicinity of central nervous system, the facial features can response endogenetic variation faithfully. Additionally, the option of monitoring a subject’s physiological signals via a remote, noncontact means for improving and enhancing the delivery of primary healthcare.
Currently, proposed solutions for noncontact measurement of vital signs such as using infrared camera or webcam to monitor latent variation from facial regions is one of a simple, low-cost method for measuring multiple physiological parameters [24]. Based on above reasons, this study chose facial temperature to monitor the variation of temperature on human body, and expected this method can mimic daily life.
This thesis still lack of respiratory results to discuss the respiratory responses when environmental conditions changed. End Tidal CO2 (ETCO2) is one of choice to monitor the variations of respiration. ETCO2 is the partial pressure or maximal concentration of carbon dioxide (CO2) at the end of an exhaled breath, which is expressed as a percentage of CO2 or mmHg. The normal values are 5% to 6% CO2, which is equivalent to 35-45 mmHg. But ETCO2 was not used in this stage, since mask method let subjects feel uncomfortable, and simultaneously affect experimental results. But respiratory issues are important in this research, it is necessary in next stage to consider respiratory signals and not disrupt normal activities. Additionally, the local variation between environment and human respiration is one of novel issue, finding the influence fact of the human respiration could have positive influence for this study.
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4. 2. 2 Physiological mechanisms
Figure 16 shows the systemic mechanism of the human body under poor indoor ventilation. Generally, gas exchange is rapid and based on Brownian motion and kinetic theory. Poor ventilation affects human physiological responses. In environments with high CCO2, responses are manifested in breathing, metabolism, and cardiovascular system. If a human stays in an environment with high CCO2, the blood SpO2 will decrease. The chemoreceptor in blood vessels responds to environmental changes and transport information to the chemoreflex in the central medulla. The central-chemoreflex is important to responding to pH changes in blood and thermoregulation. This reflex also accelerates breathing to maintain fluid balance. As breathing can increase body temperature [20], Tf was increased indirectly. A rapid HR improves blood volume in the cardiovascular system. The effect of this acceleration of gas exchange increases in the alveolar microvasculature. The main purpose of physiological response is to supply the blood with sufficient oxygen for normal organs function. Therefore, this mechanism is an internal protective mechanism for maintaining homeostasis.
Fig. 18 The systemic mechanism of humans staying inside the poorly ventilated room
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4. 2. 3 Quantity of Subjects issues
Virtually, the quantity of subject in this thesis is insufficient, doing more humanity
experiments to verify the interaction between environment and human is necessary.
However, doing humanity experiments need the permission from institutional review board (IRB) and observe the medical rules. IRB is a committee that has been formally designated to approve, monitor, and review biomedical and behavioral research involving humans with the aim to protect the rights and welfare of the research subjects. In the United States, the Food and Drug Administration (FDA) and Department of Health and Human Services (specifically Office for Human Research Protections) regulations have empowered IRB to approve, require modifications in planned research prior to approval, or disapprove research. And in Taiwan, organizations of IRB locate in public or teaching hospitals, integrating doctors’ professional knowledge to manage these societies.
This study will cooperate with department of internal neurology from Hsin Chu General Hospital, and the IRB project is in application. Department of internal neurology can supply and guide the knowledge of CNS, and have positive effect to help design experiments in this research topic. If it is possible, this study will design more fundamental experiments including respiratory responses, cardiovascular system, and thermoregulation to verify humanity mechanism, and expect 30 subjects in this study work.
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