Indoor Air Cartoon Journal, May 2023, Volume 6, #142
[Cite as: Fadeyi MO (2023). Making a case for provision of healthy indoor air: Impact of oxidative stress on human health. Indoor Air Cartoon Journal, May 2023, Volume 6, #142.]
Fictional Case Story (Audio – available online)
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There was hidden danger lurking within society. Poor outdoor air quality was increasing and compromising indoor air quality and the health of indoor occupants. Unknown to many, the link between poor indoor air quality and oxidative stress—a harmful imbalance of reactive oxygen species in the body, leading to oxidative damage responsible for various serious health problems, which include cancer was prevalent in society. The lack of awareness hindered proactive, preventive, and mitigating efforts needed to improve indoor air quality to achieve healthy indoor air for healthy living. The determination to protect loved ones and promote a healthier environment for all led a caring girl on a journey of awareness creation on what needed to be done. The journey the girl embarked on, and the life lessons she gained along the way are the subjects of this short fiction story.
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Garcia Salvador was an undergraduate at the University of Bannon, in a country called Fajumacia, studying Geology. She was struggling with her studies. She was on probation. Her cumulative Grade Point Average (GPA) was 1.95 out of a possible GPA of 5.0. She had only one semester left to ensure her GPA was at least 2.0 to avoid being dismissed from the university.
Garcia was in the first semester of Year 2 when the final probation warning was given to her. Thus, her performance in the second semester of Year 2 became a do-or-die affair to stay in the Geology programme and the university. Garcia, who did not feel attached to the Geology programme and was unsure how it would be useful to her future, found it tough to study. The fear of being expelled from the university further paralyzes her cognitive ability needed for learning.
When the second-semester result was released, Garcia was devastated. She performed much more poorly than ever before, and her cumulative GPA dropped from 1.97 to 1.62. She was expelled from the university. Garcia was disappointed in herself. She also felt she had disappointed her parents. Her parents had spent a lot of money to ensure she studied at the University of Bannon. Garcia’s parents took a loan to fund her university education. She was the first in her extended family to gain university admission. Her parents were very proud when she was admitted to the University of Bannon.
The University of Bannon was ranked the best university in the country, having more than 40 universities. Her parents believed that Garcia’s admission to the university would motivate and set a good precedent for his brother, who was nine years younger than her. Everyone in the extended family looked at Garcia’s parents with enormous respect and as a reference point for how to raise a child. Family members sought advice from Garcia’s parents at every family gathering.
Garcia’s parents had always been very proud of her. Throughout her 12 years of primary to secondary school education, Garcia was a resilient and determined girl who performed well above average in her studies. She had a passion for making a positive difference in her school’s students’ welfare. Authorities recognised her ability to change people’s lives in the primary and secondary schools she attended. She was made a prefect both in her primary and secondary school.
Garcia did well in her secondary school leaving examination (SSLE). She scored 3As and 6Bs in the subjects she registered for. However, disappointment came in her university entrance examination (UEE). Garcia scored 205 out of 400. For context, UEE questions were typically at a much more advanced level of difficulty than SSLE questions. Students must pass with at least a C grade in the required SSLE subjects and meet the required cut-off mark of a university programme to be considered for university admission.
Geology was the course offered to Garcia because of her relatively low performance in the UEE. The cut-off mark for Geology was 200, the lowest possible cut-off mark for programmes available at the university. The Geology programme cut-off mark was very low because it was not a popular course. However, the course was very tough for students in it. For perspective, 94 percent of graduates from the Geology programme graduated with second class lower or below from the programme’s inception at the university. Additionally, there had never been any first class since the programme’s inception.
Garcia was in despair because of her expulsion from the university. The pain hit her so hard that she decided that a university education was not for her, at least in the nearest foreseeable future. She did not believe in herself anymore. Her self-confidence and self-esteem were utterly decimated. She also did not know what he was good at or who she wanted to be in the future.
Fulfilling the immediate need became a priority for Garcia. She needed to find a way to support herself and, most importantly, help her parents repay the bank loan they secured for her unsuccessful university education journey. Garcia took up a job as a janitor at a local hospital. She worked at the cancer department of the hospital. Her main responsibility was cleaning after patients. She cleaned the wards. She was also responsible for cleaning and carrying patients’ urine and faeces. It was a humbling experience for her. However, she needed the money, and the hospital paid well.
As Garcia went about her daily tasks, she could not help but notice the stark reality of the increase in the number of patients dying of cancer. Her curiosity to know what could be causing cancer started when her grandmother was a patient in the hospital diagnosed with cancer, and her health deteriorated daily. The once lively and spirited grandmother grew weak, and her laughter was silenced by the struggle to breathe, and she died. Driven by her curiosity about what she had seen at the hospital and her grandmother’s death, Garcia researched in her free time to learn about the risk factors of cancer occurrence.
Garcia was surprised that the cancer incidence rate has been increasing rapidly in her country for the past 50 years. Coincidentally, three days prior, Garcia heard in the nighttime news about the unhealthy outdoor air pollution prevalent in the country that has been occurring for the past 50 years. “Could there be a link between outdoor air pollution and the cancer incidence rate?” Garcia asked herself.
Looking through the Ministry of Health’s research magazine publications, Garcia noted that although the cancer incidence rate has been increasing steadily for the past 50 years, there has been a sharp increase in its incidence rate in the past ten years. Garcia also read in another section of the magazine that smoking habits, especially among the youth, increased sporadically in the past ten years in the country. Smoking among the youth was a trend.
“Could there be a link between the rapid increase in smoking habits and the sharp increase in cancer incidence rate in the past ten years? Garcia learnt that since smoking was prohibited indoors in public buildings, many youths and older smokers smoke outside, around buildings. As a result, many non-smokers were exposed to secondhand smoke (SHS). From Garcia’s experience, there were many times when people indoors were exposed to SHS, despite the source of smoking not originating indoors. Garcia had first-hand experience with this, mostly while at the university.
Although smoking was prohibited indoors, people smoked in their apartments. Garcia and her family, including her late grandmother, lived in a building with many smokers. SHS smoking was a common occurrence, especially at night and morning. Garcia and her family were often forced to close doors and windows to reduce their exposure to SHS.
Garcia read through online information and many volumes of the MOH magazine but could not find specific answers to her questions. Her curiosity was fueled by her deep love for her grandmother and the fear that if there was a link, the health of her parents, herself, her brother, and many people exposed to SHS could be at risk.
Garcia attempted to read articles in scientific journals but could not make sense of what she was reading due to the technical jargon and lack of background in the relevant subjects. The jargon also made it painful for her to read the articles. That was when it dawned on Garcia that she needed to equip herself with relevant knowledge to help her family and many people in the country. She thought that to be taken seriously by people, having a degree in a relevant subject is essential. With the new mission and motivation to influence people’s lives positively and a sense of purpose she had never experienced since she left secondary school, Garcia decided it was time to go to university.
She registered for the university entrance examination and studied very hard despite her busy work schedule at the hospital. Garcia did well in the examination. She scored 252 out of 400. Her score was well above the cut-off mark for the environmental engineering science she applied for. Garcia decided to study at another university in the country.
Garcia’s experience at the University of Bannon was still hunting her. Even though it had been three years after her expulsion from the University of Bannon, and her cohort had already graduated. Garcia decided to enroll in a part-time Bachelor of Science degree in Environmental Engineering Science degree at the University of Wagos, Fajumacia. The part-time degree was five years instead of four years for a typical full-time engineering programme.
Garcia decided to pursue a university education as a part-time student as she needed her salary from work at the hospital to fund her university education. Furthermore, she was still paying the loan for her failed university education at the University of Bannon. Garcia was about 26 years when her latest UEE result came out. She would be about 27 years when her university study started, and she would be more than 32 years at graduation if she completed the degree. This did not deter Garcia. She had finally found something she was committed to pursuing and a mission in life.
Studying and working at the hospital was very tough on Garcia. However, her motivation, perseverance, and indomitable spirit pushed her through the difficulty. Her maturity, time management experience, and determination to rewrite her university education history made it easier for her to focus, study, and manage her studies very well.
Five years went by quickly, and Garcia graduated from the university. Hurray! Garcia did not just graduate. She graduated as the best engineering student for the graduation year. She graduated with First Class Honours in environmental engineering science. She also graduated with a minor in human biology. Her parents were very proud of her achievements.
The fulfillment Garcia got from her parents’ happiness was more fulfilling to her than the fulfillment she got from getting First Class Honours. Another icing on the cake for her was that she completed the degree without any debt. Furthermore, she had also completely paid the loan her parents got for her university education at the University of Bannon, which was unsuccessful.
Garcia’s interest in human biology stemmed from working at the hospital. While studying environmental engineering science at the university, Garcia also took skill-job upgrading training and rose to become a nurse assistant. She did this to increase her earning power, fund her university education, and support her parents.
Throughout her undergraduate education, she understood and appreciated how air pollution is a major threat to human and public health. Garcia’s major takeaway from her undergraduate study was that humans spend almost 90% of their time indoors, making exposure to air pollutants of outdoor origin occur indoors, and efforts should be taken to minimise the exposure.
The exchange of air between indoors and outdoors also contributed to most exposure to pollutants of outdoor origin present in indoor environments. She learnt that indoor environments have a significantly larger surface area to volume ratio than the outdoor environment. Thus, exposure to pollutants in indoor environments is higher than in outdoor environments, especially when humans stay longer in indoor environments.
After completing her bachelor’s degree, Garcia’s passion for indoor air quality grew stronger. She decided to continue her education and pursue a PhD in indoor air quality and health. She got a very competitive and lucrative federal government scholarship from her country’s government to pursue a PhD abroad.
The PhD scholarship came with a bond. Garcia has to return to Fajumacia to serve her bond by contributing to the education sector as part of the effort in nation-building. Garcia got admission to Macmillan University. Macmillan University was regarded as one of the top 3 universities in the world at that time. Macmillan University was a dream university for many people, including students and parents.
Garcia’s PhD study addressed a main question that had been bothering her for many years and motivated her to return to the university after her first failed attempt at university education. In some of the modules she took to fulfill the requirements of achieving a minor in human biology, Garcia learnt about the contribution of oxidative stress caused by excessive reactive oxygen species in humans to chronic diseases like cancer. The knowledge Garcia gained from the human biology modules she took also influenced the main research question that guided her PhD study.
Garcia learnt, during her undergraduate study, that NO2, a highly oxidizing agent, is very prevalent in outdoor air pollution, especially outdoor air pollution caused by vehicular traffic. Furthermore, the condition surrounding the prevalence of secondhand smoke that made it a concern for Garcia was still prevalent. An indoor air chemistry module Garcia took at the university suggested how reactive oxygen species, ROS, could be prevalent in indoor air and increase indoor occupants’ exposure to ROS.
“How does exposure to NO2 and environmental tobacco smoke (ETS) and their chemistry products when ventilation and air filters are adopted influence oxidative stress and total reactive oxygen species, ROS, in indoor air?” This was the question that guided Garcia’s PhD study. The objectives she came up with to answer the research questions were 1. To examine the impact of ventilation rate and air filter efficiency on oxidative stress and exposure to total reactive oxygen species, ROS, and indoor air pollutants; 2. To examine the impact of NO2 and ETS and their chemistry products on oxidative stress and exposure to ROS.
Garcia’s PhD research and findings became the catalyst for her transformation. Below is the extract from Garcia’s PhD’ research methodology for her award-winning PhD thesis.
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The experiments were conducted to answer the main research question and fulfill the research objectives in an air-conditioned chamber. The air-conditioning system for the chamber recirculated 90% of the volume of air from the chamber and supplied 10% of outdoor air. The approximate volume of the recirculation loop was 5m3. During the experiments, the air conditioning systems had air filters placed downstream of the mixing plenum of outdoor air and recirculated air in the air handling unit.
There were four groups in the experimental study. The groups were named the control group, NO2 exposure group, ETS exposure group, and NO2 + ETS exposure group. In the control exposure group, the chamber was assumed to have clean air because there was no injection of NO2 and ETS into the chamber. In the NO2 exposure group, NO2 was injected into the chamber. In the ETS exposure group, tobacco smoke, i.e., ETS, was injected into the chamber. In the NO2 + ETS exposure group, NO2 and ETS were injected into the chamber. For context, NO2 is a powerful oxidising agent due to its unpaired electron and high electron affinity.
A NO2 generator was used to generate NO2. The generation rate adopted had a steady state concentration considered acceptable for indoor air quality by regulatory authorities. The NO2 was generated into the outdoor air duct. The injection point was close to the outdoor air intake. The outdoor air duct was before the mixing plenum in the AHU, where fresh air and recirculated air were mixed to form the supply air exposed to air filters placed downstream of the mixing plenum in the AHU.
A cigarette smoking machine, an ETS generator, was used to ensure an ethical and consistent amount of tobacco smoke was released into the chamber. The injection was done into the outdoor air duct, similar to the case of NO2. As part of the effort to confirm the ethical requirements for this kind of research, a decision was made not to place the NO2 and ETS generators in the chamber occupied by the subjects. The injection location of NO2 and ETS simulated a condition where they originated outdoors.
An effort was also made to ensure the concentrations of ETS pollutants of interest were within the concentration limits set by regulatory authorities. Many trials were conducted to determine the injection rate of NO2 and ETS. These trials were conducted at a standard ventilation rate with no air filter in the air handling unit. Ethical approval was obtained from Institutional Review Board (IRB) to conduct the study.
For the actual experiments, four intervention scenarios were examined. The intervention scenarios were 1. Standard ventilation rate with standard filter; 2. Standard ventilation rate with enhanced-efficiency filter; 3. Enhanced ventilation rate with standard efficiency filter; 4. Enhanced ventilation rate with enhanced efficiency filter.
One hundred and forty healthy and non-smoking subjects between 21 and 35 years old were recruited for the experimental study. In this context, healthy subjects have no known or diagnosed chronic health problems. Thirty-five subjects were randomly and unbiasedly assigned to each of the four groups. Due to the limited capacity of the chamber, each experiment for each exposure group was repeated two times. Each chamber could only take a maximum of twenty subjects sitting in an office-like position.
Seventeen to eighteen subjects were assigned to be in a subgroup of each of the four exposure groups. It is important to note that a subject assigned to a sub-group or group did not participate in another sub-group or group’s experiments. Each subject participated in a total of four experiments.
The random assignments of subjects were done through computer-generated random numbers. This ensures that each subject has an equal chance of being assigned to any group. Random assignments were done to ensure the assignments were unbiased and not influenced by researchers’ or subjects’ preferences.
The following is the overview of how data were collected for oxidative stress, ROS in the indoor air, and indoor air pollutants of interest. The details of the process of measuring and the instrumentation used were provided in Garcia’s PhD thesis. The research team determined the overall oxidative stress burden in the indoor air through measurements of total ROS in the indoor air.
Total ROS measurement was used to assess oxidative stress levels in the indoor air without specifically identifying or quantifying each ROS separately. In determining the total ROS, air samples were collected using sorbent tubes. Air samples collected were labelled. Samples were prepared based on the chosen analysis method to increase the accuracy of the measurement. Analysis was done to determine the total ROS in the sampled air effectively.
A fluorescent probe known as dichlorofluorescein (DCF) was used to determine the total ROS in the sampled air. The fluorescent probe can react with a wide range of ROS, including hydroxyl radical (–OH), superoxide radical (02–), hydrogen peroxide (H2O2), peroxynitrite (ONOO-), and singlet oxygen (lO2), producing a fluorescent signal that is proportional to the total oxidative stress.
The indoor air pollutants of interest are NO2 and those associated with ETS and its chemistry products with NO2. The pollutants of interest associated with ETS and its chemistry products with NO2 were nicotine, carbon monoxide, total volatile organic compounds, formaldehyde, benzene, toluene, secondary organic aerosols, and semi-volatile organic compounds like N-Nitrosonornicotine and peroxyacetyl nitrate known to be generated from NO2 reaction with ETS.
The secondary organic aerosols are particulate matter (PM). The PM measured ranged from 0.3 nanometers to 500 nanometers. Thus, ultrafine particles, PM0.1, and fine particles, PM2.5, were measured. Some pollutants were measured using continuous measurements, while some were determined from air sampled four times during an experiment.
Spot measurements through air sampling were done at S0, which means before subjects entered the chamber and injection of NO2 and/or ETS, where applicable, started; at S1, which means 1 hour after; at S2, which means 2 hours after; and at S3 which means 3 hours after subjects enter the chamber and injection of NO2 and/or ETS, where applicable, started. The 3 hours after was also when the injection of NO2 and/or ETS, where applicable, stopped. The injection stopped immediately after samplings at S3 were done. The fourth spot measurement, S4, was done just before subjects exited the chamber about 4 hours after entering it and approximately 1 hour after the injection stopped.
This means the subjects stayed in the chamber for 1 hour without injection of NO2 and/or ETS, where applicable. Subjects stayed in the chamber for 4 hours, and continuous measurements of some pollutants were done for 4 hours and 30 minutes.
Spot measurement through air sampling and analysis for air pollutants were done in the laboratory using gas chromatography-mass spectrometry (GC-MS) to determine the concentrations of nicotine, formaldehyde, benzene, toluene, and the SVOCs of interest at S0, S1, S2, S3, and S4. Other air pollutants of interest were determined with continuous measurements in the chamber. For pollutants that were measured continuously, their total concentrations at S0, from S0 to S1, from S1 to S2, from S2 to S3, and from S3 to S4 were analysed in addition to the analysis their total concentration over the 4 hours 30 minutes period.
To determine the oxidative stress in the subjects, saliva samples were taken to measure biomarkers that can provide indications. For each experiment, subjects spent 30 minutes in a room where their saliva was taken before they were told to enter the chamber. This means the saliva sample of each subject was taken at S0. Saliva samples were also taken at S1, S2, S3, and S4. A passive drool salivary sampling procedure was applied for saliva collections. Subjects expelled saliva into a labelled sampling tube. Biomarkers related to oxidative stress were measured in saliva collected. The biomarkers of interest in this study were 1. Malondialdehyde, MDA; 2. 3-Nitrotyrosine, an example of protein carbonyl; 3. 8-hydroxydeoxyguanosine, 8-OHdG.
MDA is an indication of oxidative damage to lipids which are cellular components that occur as a by-product of lipid peroxidation. 3-Nitrotyrosine is an indication of oxidative damage to proteins which are cellular components. 8-OHdG is an indication of oxidative damage to DNA. An increase in each of the biomarkers in saliva would indicate an increase in oxidative stress and damage in the subjects.
The saliva analysis only provides insight because of associated uncertainty. The uncertainty is because saliva biomarkers may not directly reflect systemic oxidative stress, as the content of saliva can vary and may be influenced by local factors within the oral cavity.
To further reduce the uncertainty, subjects were advised not to take spicy food, citrus fruits, coffee, and alcohol on the day of the experiment. Precautions were taken to avoid contamination of collected saliva samples due to the collection procedure and sample storage and handling.
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The experiments were successfully carried out, and the following were extracts of the key findings from Garcia’s PhD thesis.
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1. The measured three oxidative stress biomarkers levels and total ROS in the indoor air at S1 to S4 for NO2, ETS, and NO2+ETS exposure groups were significantly higher than those measured in the control group for all four intervention scenarios.
2. The measured three oxidative stress biomarkers levels and total ROS in the indoor air at S1 to S4 for the NO2 exposure group were higher than those measured in the ETS exposure group for all four intervention scenarios. NO2 is a potent oxidant that can directly induce oxidative damage in tissues, potentially leading to greater oxidative stress than the oxidative stress generated by ETS exposure.
However, the observed difference between NO2 and ETS exposure groups’ effects was not significant. The difference between NO2 and ETS exposure groups at S4 was barely noticeable as measurements were done 1 hour after NO2 and ETS injections had been turned off in the NO2 and ETS exposure groups, respectively. These observations were consistent with all the intervention scenarios.
3. The measured three oxidative stress biomarkers levels and total ROS in the indoor air at S1 to S3 for the NO2+ETS exposure group were significantly higher than those measured in each NO2 and ETS exposure group for all four intervention scenarios. The measured values for NO2+ETS were higher, but not significant, than those in each NO2 and ETS exposure group at S4, as measurements were done 1 hour after the deliberate injection of the air pollutants had been turned off in these exposure groups. These observations were consistent with all the intervention scenarios.
4. The level of the three oxidative stress biomarkers and total ROS measured at S0 to S4 were very low in the control group for all four intervention scenarios. For all four intervention scenarios examined, the biomarkers and total ROS levels at S0 for the control group were similar to those measured in the NO2, ETS, and NO2+ETS exposure groups at S0, as there was no injection of pollutants during this period.
5. There was a significant increase in the levels of all three biomarkers and total ROS from S0 to S1 for all experiments conducted for the NO2, ETS, and NO2+ETS exposure groups.
6. There was an increase, but not significant, in the levels of the three biomarkers and total ROS from S1 to S2 and S2 to S3 for NO2 and ETS exposure groups. The measured biomarkers levels and total ROS decreased significantly from S3 to S4 for these three exposure groups because S4 measurements were done 1 hour after the air pollutants deliberately injected were turned off. A significant decrease from S3 to S4 was also observed for biomarkers levels and total ROS measured for NO2+ETS exposure groups. These observations were consistent with all four interventions examined.
7. An increase in the measured levels of the three biomarkers and total ROS from S1 to S2 and S2 to S3 was observed for the NO2+ETS exposure group. The differences were significant at standard ventilation rate with standard efficiency filter. The differences were not significant but noticeable at enhanced ventilation rate with standard efficiency filter. No noticeable difference was observed for standard ventilation rate with enhanced efficiency filter and enhanced ventilation rate with enhanced efficiency filter interventions.
8. The intention of reducing the measured three oxidative stress biomarkers levels and total ROS was best achieved at an enhanced ventilation rate and enhanced efficiency filter. The next performing intervention was standard ventilation rate with enhanced efficiency filter followed by enhanced ventilation rate with standard efficiency filter. The least performing intervention, although useful, was the standard ventilation rate with standard efficiency filter. The observed effectiveness of enhanced ventilation rate with enhanced efficiency filter was most evident at NO2+ETS and least evident for the control group.
9. The intention of reducing measured indoor air pollutants concentrations was best achieved with an enhanced ventilation rate with an enhanced efficiency filter. The next performing intervention was standard ventilation rate with enhanced efficiency filter, followed by enhanced ventilation rate with standard efficiency filter. The least performing intervention, although useful, was standard ventilation with a standard efficiency filter.
10. The observed order of the results suggests that enhanced ventilation rate provides the benefit of enhanced dilution of air pollutants, especially for air pollutants that originated in the chamber due to indoor air chemistry. The potential negative impact of enhanced ventilation of introducing more pollutants of outdoor origin can be effectively mitigated with an enhanced efficiency filter. NO2 and ETS injections into the outdoor air duct near the outdoor air intake were done to simulate a situation in which the air pollutants were present in the outdoor air entering the air conditioning system.
The implication of the observed results is that enhanced efficiency filters should be given high priority in parts of the world where the outdoor environment is highly polluted. This is especially important for pollutants that can increase ROS and oxidative stress leading to serious health problems. This should be done to maximise the benefit inherent in enhanced ventilation rates. This recommendation is supported by observations in the other intervention experiments conducted in this study.
11. The fact that the standard ventilation rate with enhanced efficiency filter performed better than enhanced ventilation with standard filter in the research study with the source of pollutants from outdoors suggests something. It suggests the importance of taking the efficiency of filters seriously when adopting ventilation and increasing its rate in areas where the outdoor environment is polluted.
In such an environment, ventilation will perform two functions. The two functions are diluting indoor air pollutants and transporting air pollutants from outdoors to indoors. These two functions compete. The superior function will determine indoor air quality. The higher the concentrations of air pollutants in the outdoor environment and transported into indoor environments, the more the dilution benefit of ventilation diminishes.
Adopting and placing air filters or air cleaning agents in the path of outdoor to indoor transport of pollutants of outdoor origin and those recirculated indoors to arrest the air pollutants will help the dilution benefits to be more evident and improve indoor air quality. Improving indoor air quality increases the chance of having healthy indoor air. Thus, the higher the efficiency of a filter or air cleaning agent, the higher the achievement of dilution benefit inherent in ventilation, as suggested by findings from this study.
12. The least performing intervention observed in the case of standard ventilation rate with standard efficiency filter suggests the importance of increasing ventilation rate to reduce oxidative stress, ROS, and exposure to measured indoor air pollutants. Increasing ventilation will increase the dilution rate of the air pollutants generated inside the chamber through indoor air chemistry. Unsurprisingly, the benefit of increasing ventilation was more evident in the measured secondary organic aerosols generated in the chamber during the experiments.
Thus, standard ventilation rate performance was lower than enhanced ventilation rate performance. Lowering the filtration efficiency to standard efficiency means the benefits of reducing NO2 and ETS pollutants generated from outside the chamber were reduced. There was also a decrease in the trapping rate of pollutants that are passed over the filter in the AHU several times through a phenomenon called recirculation.
13. For all experimental conditions, the increase in total ROS measured positively and highly correlated with the increase in each of the oxidative biomarkers’ levels measured. Each measured indoor air pollutant concentration also correlated positively with an increase in each of the measured oxidative biomarkers’ levels.
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Garcia completed her PhD study in 4 years. Garcia’s multitasking experience allowed her to marry and have a child while completing a PhD at the same time. Garcia married another scholarship recipient from her country, Fajumacia. Her husband’s name was Alex. Alex got a bonded scholarship to pursue a postdoctoral fellowship at Macmillan University. Alex returned home with their son after completing his postdoctoral fellowship to serve his scholarship bond.
With her PhD in hand and permission from her home country’s government to defer the serving of her bond associated with her PhD scholarship, Garcia proceeded to work at Macmillan University as a postdoctoral fellow. During her three years of postdoctoral studies, Garcia developed a deep understanding of the complex dynamics of indoor air. She explored advanced technologies, sustainable design practices, and policy frameworks to promote healthier indoor air. Her research focused on an effective approach to achieving effective knowledge exchange of environmental, social, and economic implications of improving indoor air quality.
Upon completing her postdoctoral fellowship, Garcia became a promising expert in indoor air quality. Armed with her knowledge, passion, and personal experience, she embarked on a mission to impact locally and globally. First, she must return to her home country to serve her bond. She was offered a position as an Assistant Professor in the Civil and Environmental Engineering Department at the University of Bennon.
Wow! Garcia became an Assistant Professor at the university she was expelled from as an undergraduate student. Garcia had come a full circle. Garcia was a source of inspiration to many students, especially those struggling with their studies. A few years later, Garcia was promoted through the ranks and became a Full Professor. She made impacts locally and globally.
Garcia founded an educational initiative called “Healthy Indoor Air for All” to raise awareness about the importance of healthy indoor air and how to achieve it. She collaborated with universities, industry professionals, and community organisations to create public educational resources, workshops, and seminars to enhance an educational experience on healthy indoor air delivery.
Garcia’s goal was to empower students, industry professionals, community members, and academics with the knowledge and tools to create healthier indoor environments. Garcia shared the following in one of her public engagements for knowledge exchange about healthy indoor air delivery.
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Reactive oxygen species (ROS) generated during cellular metabolism in the human body are important for healthy bodily functions. However, when ROS is in excess than needed by the body or exceeds the antioxidant’s defence capacity, a phenomenon known as oxidative stress, the excess ROS increases the rate at which ROS reacts with (oxidise) cellular components, lipids, proteins, and DNA, to cause oxidative damage. Oxidative stress could lead to cardiovascular diseases, neurodegenerative diseases, cancer, diabetes, inflammation, impaired reproductive and respiratory health, skin ageing, psychological problems, and many more.
The presence of air pollutants in indoor air, especially at unhealthy levels, and their interactions can generate ROS in indoor air. The ROS formed, and other indoor air pollutants can find their way into the human body. Indoor air pollutants in the human body can lead to more ROS production in the body through direct generation due to chemical reactions, induction of inflammatory responses, impairment of mitochondrial respiration and electron transportation chain activity, and activation of oxidative enzymes.
What are you doing to improve indoor air quality to make it healthy for indoor occupants? The provision of cleaner air through air pollutants source elimination or reduction, ventilation, and air filtration or cleaning is essential to reduce the risk of oxidative stress and its impact on human health. ….
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Garcia’s efforts did not go unnoticed. Her work gained recognition both locally and globally. She was invited to speak at international conferences, share her research findings, and collaborate with experts worldwide. Garcia became a leading voice in the fight for healthier indoor air through her dedication and unwavering commitment.
Her impact was profound. The knowledge she shared through “Healthy Indoor Air for All” reached countless individuals and organisations, transforming how they thought about and approached indoor air quality and healthy indoor air delivery. Garcia’s initiatives led to policy changes and improved building designs, construction, and management. Her initiatives also increased awareness of the health risks of poor indoor air.
Garcia’s effort led to the awareness of effective strategies for identifying and eliminating or reducing sources and emission rates of indoor air pollutants. There was also high consciousness of adopting adequate ventilation rates and air filters to maximise the degree to which indoor air quality is achieved to increase the chances of enhancing healthy indoor air delivery.
As Garcia reflected on her journey, she realised that her struggles and setbacks had not defined her but had fueled her determination to succeed. From a young girl expelled from university to a respected expert in healthy indoor air delivery, Garcia had found her strength and purpose.
Her story inspired many, reminding them that setbacks are not the end but an opportunity for growth and transformation. Garcia’s legacy lived on through the countless lives she touched and the healthier indoor environments that resulted from her tireless efforts. And so, Garcia’s journey continued, with her unwavering dedication to creating a world where clean and healthy indoor air was accessible to all. The End!
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