Indoor Air Cartoon Journal, October 2021, Volume 4, #123

[Cite as: Fadeyi MO (2021). Take a human assessment of the risk level involved in exposure to indoor air seriously. Indoor Air Cartoon Journal, October 2021, Volume 4, #123.]

The primary purpose of a building is to provide safety to its occupants. The determinants of success for this safety lie in the comfort, convenience, and awareness it provides to the occupants. These three determinants are needed to have a healthy living, working, and learning. Unfortunately, there are threats from outside and inside a building to the achievement of the needed safety. One of such threats is air pollutants.

The mere presence of a person in a building breathing indoor air means the risk, i.e., the possibility, of the person experiencing harm caused by the indoor air exist, rated as 1. If the person is not present, the possibility will not exist, rated as 0. However, the probability, i.e., likelihood, of the indoor air causing harm to the person will range between >0 and 1. “1” in this case means a certainty, i.e., harm will occur without any doubt.

A risk assessment is done to determine the probability. Exposure to indoor air containing air pollutants will increase the probability. The higher the toxicity of a pollutant a person is exposed to, the higher the probability. The higher the concentration of the toxic pollutant, especially when resident in the indoor air for an extended period, the higher the probability of harm due to the pollutants occurring to the exposed person. The longer the exposure period to the indoor air containing the toxic pollutants and the higher absorbed dose of the exposed person, the higher the probability of getting to the certainty of harm occurring to the person.   

Thus, the exposure level is a form of vulnerability. Vulnerability is the extent of liability of getting harmed. The vulnerability changes depending on what one is exposed to, the duration of exposure, and the absorbed dose rate. The economic and social situation of building occupants can also influence their exposure level.

A poorly ventilated and highly crowded indoor environment will increase the number of building occupants exposed to high concentrations of indoor air pollutants. The probability of exposed persons getting harmed by air pollutants, i.e., risk level, in such an environment will move in the direction of certainty.  

Reducing the ability of indoor air to cause harm is believed to be the most reliable way of reducing the probability of harm occurring to the exposed person. Eliminating or reducing the sources introducing pollutants into indoor air is the most effective way of reducing the ability of indoor air to cause harm. However, eliminating or reducing the sources can be challenging, as evident from the COVID-19 experience. Thus, it is important to find another way of reducing the ability of indoor air to cause harm.   

The next best option is ventilation, as suggested by many studies. The adoption of ventilation with air cleaning and disinfection solutions will further enhance the effectiveness of ventilation in reducing the potential of indoor air causing harm to humans. Read Li et al. (2021), Morawska et al. (2020), and Srikrishna (2020) for a better understanding and appreciation of the benefits inherent in ventilation. The outcome of any risk assessment done with scenarios where the engineering solutions mentioned above were adopted is bound to produce results of lower exposure than scenarios where the engineering solutions were not adopted.

Risk assessment done without considering how people will respond to the idea of adopting the engineering solutions does not respect reality. What does it take to make a risk assessment respect reality? Respect how human behaviour is formed. It is as simple as that. Respect means to consider how humans perceive a situation, how humans interpret their perception, and how the interpretation affects their behaviour.

How is the human perception formed? How is perception interpretation formed? How is the effect of perception interpretation on human behaviour formed? How does human behaviour influence the probability of exposed persons getting harmed by indoor air pollutants, i.e., risk level? These questions will be answered to understand better the importance of taking a human assessment of the risk involved in exposure to indoor air seriously.

Sensation occurs when a sense organ is stimulated when exposed to a stimulus, like an indoor air pollutant. The sense organs include the eye, nose, tongue, ear, and skin. The sensations from the sense organs are transported to the brain through nerve cells connecting sense organs to the brain. When the brain interprets the sensation, information known as perception is produced.

Examples of perception include (i) nose perceiving odour or nose irritation due to contact with air pollutants, (ii) seeing polluted air, seeing dust on indoor surfaces, or eye irritation due to contact with air pollutants, (iii) tasting air pollutants resulting into coughing or throat irritation, (iv) skin irritation due to contact with air pollutants. Perception of learning can also occur through reading with the eye or touching, in the case of the blind, of learning materials on indoor air pollutants and possible impacts on humans.

The sense organs are essential as they are the first layer of defense mechanisms that contribute to the generation of perception about external stimuli to the body. Air pollutants can cause harm to internal organs when they find their way to the human body. Sensations from the internal organs get to the brain, where perception is formed to facilitate on-time mitigating strategy before death occurs through nerve cells.

The inability of sense organs to pick up sensations from external stimuli or the nerve cells to relay sensations to the brain will increase the probability of a risk occurring. The physiological condition of a brain will also determine the quality of its sensation interpretation which produces perception. This means human psychology has a major influence on human perception formation.

Human perception does not directly influence human behaviour. Humans interpret their perceptions based on the implications on their comfort and convenience and awareness level on what needs to be done, i.e., what they know or need to know. Humans react to the outcome of their perception interpretation.

Suppose a person perceives poor indoor air quality, its health effects, or possible poor health effects. In that case, human intuition will set in to reduce the resulting discomfort and inconvenience in doing daily activities, working, or learning, and to have information on what is going on and needs to be done. Perception interpretation also motivates the kind of solutions humans pursue or favoured to achieve the basic human needs – comfort, convenience, and awareness.

Suppose occupants perceive the probability of indoor air causing harm to be very low, even though the probability is actually high. In that case, they may not take any action to improve the air quality because their perception interpretation would mean the indoor air will not cause discomfort and inconvenience to them due to lack of awareness.

A typical risk assessment would assume human decision-making is one-directional and will or expect to use known engineering solutions to reduce indoor air pollutants concentrations, thereby reducing the risk level. The engineering solutions include, i.e., ventilation and air-cleaning, and air disinfectants. However, human decision-making is dynamic and complex in nature. A risk assessment tool developed based on this poor assumption on human decision-making will make the tool far from reality.

Humans will likely favour solutions they believe will have a lesser impact on their comfort and convenience and provide them information on the situation they are experiencing. At the same time, they are seeking for a solution to reduce the discomfort and inconvenience brought by air pollutants. They may also not want to compromise the comfort and convenience in other areas of their life. For example, occupants in a residential building may be reluctant to open their windows to increase the ventilation rate needed to reduce indoor air pollutants concentrations if they believe their privacy and security will be compromised.

Suppose the occupants favoured the comfort and convenience brought by having privacy and security over low concentrations of indoor air pollutants. In that case, they will not adopt ventilation or adopt it appropriately even risk assessment efforts suggest the adoption of ventilation is essential for healthy indoor air. This means the human assessment of the probability of indoor air pollutants causing harm to them is not considered high enough to warrant the adoption of ventilation or adopt it appropriately.

In contrast, the probability of lack of privacy and security causing harm they cannot afford to experience or sacrificed for low indoor air pollutants concentrations is considered high. Thus, action is taken to provide a solution that will provide privacy and security instead of low ventilation. That solution may mean not opening windows.

The non-availability of real-time information on the benefit of ventilation in reducing indoor air concentration may also contribute to the opening of a window to be less favourable to closing it for privacy and security concerns. However, it is important to note that while awareness of the benefit of a solution adopted can be useful in favouring it, the human need for comfort and convenience they do not want to sacrifice will always be favoured in decision-making.

In such a situation, the probability of harm occurring to the person exposed to the indoor air containing pollutants will be higher as they favour their privacy and security more. This article’s key message is that any indoor air risk assessment tool that does not consider the dynamic and complex nature of the human decision-making process informed by the need for comfort, convenience, and awareness is far from reality.

Thus, an indoor air risk assessment tool that does not consider the dynamic and complex nature of human decision-making may inadvertently increase the probability of indoor air causing harm to humans exposed to the air. The sentiment is shared by Aerts et al. (2018) in their study addressing the importance of integrating human behaviour dynamics into flood disaster risk assessment. Thus, the case made in this article can be transferred to other aspects of life with the primary goal of making people safe.

Research efforts are needed to develop an indoor air risk assessment tool that considers the dynamic and complex nature of the human decision-making process. Design, engineering, computer science, psychology, and human behavioural science expertise are needed to develop indoor air risk assessment tools that consider the dynamic and complex nature of the human decision-making process.

Such a risk assessment tool can be used to develop or adopt a solution that can effectively reduce indoor air pollutants concentrations and provide users with comfort, convenience, and awareness needed in the situation they find themselves in.