A Measure of Combustion-Generated Pollutants in University Laboratories and their Effects on the Indoor Air Quality

Combustion is one of the fundamental processes in learning and teaching in laboratories that leads to the release of gaseous pollutants that are both hazardous and a threat to the environment and health of individuals. This paper sought to measure the amount of combustion pollutants generated and their effects on the indoor air quality of a typical university laboratory using some selected laboratories in Ahmadu Bello University Zaria as a case study. The Combustion pollutants were measured using an IMR 1400C gas analyser. At the same time, its effects were assessed using a well-structured questionnaire designed and administered to hundred and twenty-seven laboratory users who were randomly selected. Data collected from the questionnaires were analysed using computer-based SPSS software. The results revealed that CO during combustion exceeded the ASHRAE 62 and NAAQS limit of 9ppm, reaching up to 45ppm at some points; also, oxygen was observed to be at a critical level of 20.9% and at some point falling below the limit to 20.4%. It was also observed that fatigue (RII: 0.81) is the most prominent symptom of poor indoor air quality during combustion, among other symptoms like coughing and sneezing, dryness and irritation of eyes and throat, sinus congestion, shortness of breath and headache, arranged in the order of intensity. The absence of functional fume hoods, laboratory congestion, and inadequate ventilation systems intensify the discomforting effect of combustion-generated pollutants in laboratories. Thus, it is recommended that fume hoods should be well maintained for functionality and installed in Laboratories where they do not exist (chemistry lab I). Finally, providing adequate ventilation systems in the laboratories would help increase safety in labs for learning and teaching purposes.


Introduction
Interest in the role of air quality in health and disease dates back to antiquity. In the treatise on "Airs, water, and places", Hippocrates drew attention to the impact of polluted air, among other transmission media, on disease burden. For centuries, the emphasis on pollutionassociated air problems was mainly placed on outdoor air; concerns about indoor air quality are relatively recent in comparison (David, 2010).
The National Health and Medical Research Council (NHMRC, 2009) defines indoor air as air within a building occupied for at least one hour by people of varying states of health. This can include the office, matter like nitrogen oxide (NO2), sulphur dioxide (SO2), carbon monoxide (CO), formaldehyde, and polycyclic aromatic hydrocarbons (PAHs). However, in industrialised countries, in addition to NO2, CO and formaldehyde, radon, asbestos, mercury, human-made mineral fibres, volatile organic compounds, allergens, tobacco smoke, bacteria, and viruses are the main contributors to indoor air pollution (David, 2010).
A growing body of scientific evidence indicates that the air within homes and other buildings can be more polluted than the outdoor air in even the largest and most industrialised cities. In addition to daily human activities that lead to the generation of indoor air pollutants, combustion sources and activities, especially in laboratories, contribute to carbon dioxide (CO2), sulfur dioxide (SO2), CO, nitrogen dioxide (NO2), and particulate matter (PM) emissions into indoor air environments ( Awbi, 2003).
The intrinsic nature of the health effects from indoor air pollutants is that they may be experienced soon after exposure or, possibly, years later. Immediate effects may appear after a single or repeated exposure (Tran, Park and Lee, 2020). These include irritation of the eyes, nose, and throat, headaches, dizziness, and fatigue. Such immediate effects are usually short-term and treatable. Sometimes the treatment eliminates the person's exposure to the source of the pollution if it can be identified.
The World Health Organisation, as of 2002, estimated that indoor air pollution is responsible for roughly 1.6 million deaths each year. However, the recent update, as of 2020, shows that indoor air pollution (IAP) is responsible for the deaths of 3.8 million people annually (WHO, 2020), with its symptoms ranging from acute lower respiratory infections, chronic obstructive pulmonary disease, lung cancer, and other diseases. Indoor air pollution from biomass contributes to about 2.6 per cent of the global disease burden. Hromadka, Korposh, Partridge, James, Davis, Crump, and Tatam (2017) indicated that decreased IAQ could negatively affect human health by causing building-associated illness.
In an academic environment, laboratories are a significant place where combustion activities are mainly carried out, usually during experimental activities. According to Merriam-Webster, a laboratory is a room or building equipped for scientific research, teaching, or manufacturing drugs and chemicals. From the definition, it can be established that combustion is one of the basic processes in a laboratory. Thus, the question now is: 'how safe is the indoor air quality of such laboratories owing to the activities carried out in them? This paper measures the combustion-generated pollutants in a typical university laboratory after an experiment requiring combustion activities. It also examines the laboratory users' perception of the impact of combustion-generated pollutants on the indoor air quality of the laboratories, considering the users' length of exposure during experimental activities.

Literature review
The concept of indoor air pollution is a contemporary one, which has stirred up much research with the general aim of emphasising the health impact of poor indoor air and the identification of the major pollutants of indoor air. Previous studies are reviewed in this section. Saravanan (2004), in a general study of indoor air, established that the significant factors that determine indoor air quality are: i) The nature of outdoor air quality around the building; ii) The ventilation rate of the building; iii) The materials used in the construction of the building (presence of chemicals); iv) The activities that go on inside the interior (cleaning, cooking, heating, etc.); and, v) The use of household chemicals.
Saravanan (2004) identified some of the sources of the pollutants as; radioactivity (the emissions from uranium in the soil or rocks on which the houses are built, Volatile Organic Compounds (VOCs) usually from aliphatic and aromatic compounds, chlorinated compounds with formaldehyde being in many locations). The emphasis of the sources of indoor air pollutants was on indoor combustion activities. The combustion of fuels, such as oil, gas, kerosene, and so forth, inside a building contributes to the concentration of VOCs and is also a source of stable inorganic gases. The common indoor pollutants due to the combustion of fuels are particulate matter, oxides of nitrogen, oxides of sulphur, carbon monoxide, hydrocarbons, and other odour-causing chemicals. Saravanan (2004) concluded that indoor air pollution is one of the significant problems that must be solved since a large part of human life is spent indoors. All necessary precautions to eliminate or minimise the harmful effects of indoor air pollution need to be taken.
To help elucidate more fully the extent of hazards caused by the combustion of pollutants in China, Smith and Zhang (2005) studied indoor air pollution from household fuel combustion. They estimated that air pollution from solid waste in China is responsible for 420,000 premature deaths annually, with more than 300,000 attributed to the pollution of the urban outdoor environment.
Smith and Zhang (2005) reviewed nearly 200 publications in China reporting health effects, emission characteristics, and/or indoor air pollutants concentrations associated with solid fuels. Smith and Zhang (2005) also took measurements in 122 individual studies, concluding that indoor air pollutant concentrations exceeded health standards in many households.
In like manner, Stanley (2010) assessed the environmental suitability of electric power generators for power supply to buildings to devise appropriate control measures for a cleaner environment. The assessment was for buildings within the Kaduna metropolis, and the approach adopted was the use of a well-structured questionnaire and an IMR 1400C combustion gas analyser. The research results showed that the level of awareness of health hazards caused by generators was high and that the mean concentration of SO2 and NOx indoors was higher than the FEPA limits (0.01 ppm and 0.04-0.06 ppm), respectively. The research also revealed that none of the ambient pollutants at the point source met the WHO and FEPA limits.
The above review itemises the contribution of various researchers in evaluating the impact of combustion activities on indoor air quality and environmental conditions. And at this point, it can be seen that combustion is a significant source of pollutants generation in the environment. Thus, this paper seeks to evaluate the impact of combustion activities in the laboratories on the indoor air quality of the laboratories.

HVAC requirements for a laboratory
Several types of research have been done into the heating, ventilation and air conditioning (HVAC) requirements for a laboratory, emphasising the energy usage common to laboratories and the comfort requirements. According to Lindsay (2010), an HVAC engineer's prime concern when planning or constructing any laboratory building is the safety of the building's occupants. The system must operate to specification and meet appropriate regulations. To this end, many older laboratories were designed with little regard for energy efficiency. That's no longer obtaining, and designers must account for operating costs and functionality (Lindsay, 2010).
A laboratory building consumes five to ten times more energy than a typical office building or school. HVAC systems consume almost 70% of a laboratory's energy. According to Labs21 (2010), a voluntary partnership program is dedicated to improving U.S. laboratories' environmental performance. The majority of this HVAC energy consumption originates from cooling (22%), and ventilation (44%) loads that help the laboratories function safely (Lindsay, 2010).
The high energy use can be attributed to high airchange requirements, large internal heat gains from laboratory equipment, and, in many cases, continuous hours of operation (Gordon, 2010). Vendors are developing new technologies or adapting older ones to help reduce HVAC energy consumption with a push toward a more energy-efficient laboratory environment. Lindsay (2010)'s emphasis was more in line with HVAC requirements for laboratories as an energy-saving measure and not on the adequacy of indoor air quality for laboratories.

Methodology
A measure of the amount of the combustion-generated pollutants in selected laboratories was conducted with the help of a sensitive gas analyser, the "IMR 1400C", to establish the presence and amount of the combustion pollutants present in the air before, during, and after the combustion processes. The gas analyser was used to measure and calculate the amount of the following: oxygen (O2), carbon monoxide (CO), Carbon dioxide (CO2), Oxides of Nitrogen (NOx), and Sulfur dioxide (SO2).
In addition to the measurement, a survey of laboratory users' (Staff and students) perception of the impact of combustion-generated pollutants on indoor air quality was conducted. A well-structured questionnaire was designed and administered to staff and students (laboratory users) of Ahmadu Bello University, Zaria. A total of 140 questionnaires were distributed, of which 127, representing 90.7%, were completed correctly and returned. The major issues addressed in the survey include the presence of the necessary Heating, Ventilation and Air Conditioning System; the presence and functional state of the fume hoods; and other related factors like the frequency of maintenance of the HVAC system that can influence the effects of combustion pollutants on the indoor air quality.

Data analysis procedure
The presence and the number of pollutants determined by the IMR 1400C gas Analyser were tabulated along with the acceptable limit provided by the ASHERA Standard 62 for a healthy environment. Also, most of the questionnaire questions assessed some indices of utilisation on a five (5) point Likert scale. The data analysis, therefore, employed the following steps.
a. Computation of the mean using the weighted average formula Where, ∑fx = is the total weight given to each attribute by the respondents. ∑f = is the total number of respondents in the sample. K = is the highest weight on the Likert scale.
Results were classified into three categories as follows (Othman et al., 2005) when: RII<0.60 -it indicates low frequency in use 0.60≤RII<0.80 -it indicates high frequency in use. RII≥0.80 -it indicates a very high frequency in use.

Data presentation, analysis, and discussion
The results of the measurements and analysis of the questionnaires are presented in this section under two broad headings -the presentation of the combustiongenerated pollutant measurement and the results of the questionnaire analysis.

Presentation of Measurements of the Combustion-Generated Pollutants
Data from the result of the measurements taken are presented in Tables 1-6 From Table 1, it can be observed that CO often exceeded the permissible limit, especially during the combustion process, rising to (45ppm against the 9ppm limit). It can also be observed that the oxygen levels were at the critical level and even a few points below the limit, increasing the tendency of incomplete combustion. Table 2 shows that the most reoccurring pollutant that exceeds the limit is CO, especially during the combustion process rising to (45ppm). Table 2 shows the measurement of the pollutants at three different points before the combustion activities and during and after the combustion activities. The trend of rising and falling of the amount of pollutants within the interior is also presented in Table 2. These measurements are peculiar to the SBRS Lab II. Table 3 presents the number of pollutants measured at three different points within the chemistry SBRS Lab III before, during, and after the combustion activities in the laboratory. From Table 3, it can be observed that CO is the pollutant that is constantly generated beyond the provision of the limit (9ppm) in the three different sessions of the experiments. It is observed that there was no SO pollutant recorded throughout the first session of experimentation, and there is a varying level of oxygen, usually falling below the limit. Table 4 presents the amount of pollutants measured at three different points within the Chemistry Multi-Purpose Lab before, during, and after the combustion activities in the laboratory. From Table 4, it can be observed that CO is the pollutant that is more generated even in the three different sessions of the experiments.         (2020) Where: A1, A2, A3, B1, B2, B3, C1, C2, and C3 are all measurement points, while 1, 2, and 3 are experiment sessions.        Table 5 presents the amount of pollutants measured at three different points within the Physical Chemistry laboratory before, during, and after the combustion activities in the laboratory. Table 5 shows that, similar to the other laboratories studied, CO is a pollutant frequently generated beyond the limit provision (9ppm). It can also be observed that the oxygen content as measured was not consistent throughout the measurement.
While Table 6 presents the amount of pollutants measured at three different points within the chemistry masters' student laboratory before, during, and after the combustion activities in the laboratory. Also, it was observed that CO is the pollutant that is more generated even in the three different sessions of the experiments.

Presentation of the Results of the Questionnaire Analysis
Data from the expert opinion survey are presented in Table 7. Table 7 shows that most respondents opined that their work entails combustion (74.0%). Also, as opined by the respondents, the gas burner is the major heat-generating device frequently used in laboratories (70.1%). Concerning the presence of a functional fume hood installed in the laboratory, most respondents (with a frequency of 47.2%) were unaware of its existence and functional status; this corresponds to 47.2% of the respondents.

Combustion and ventilation in laboratories
The respondents' perceptions concerning the impact of combustion activities in the laboratory and the evaluation of the adequacy of the ventilation system were also assessed. Table 8 below presents the results of the assessment. Table 8 reveals that combustion is a source of discomfort, as observed by 92.1% of the respondents. Also, Table 8 shows that combustion was more discomforting of all the processes identified (54.3%). The ventilation system is inadequate, as attested to by 79.5% of the respondents.   : Ranking of the health symptoms of poor indoor air quality Source: Field Survey, (2020) Where: 1 = strongly disagree, 2 = disagree, 3 = undecided, 4 = agree, 5 = strongly agree  (2020) Where: 1= not a cause, 2 = not a major cause, 3 = barely a cause, 4 = a cause, 5 = always a cause

Health symptoms of poor indoor air quality
Several health symptoms of poor indoor air quality were assessed, and the respondents ranked these symptoms. Table 9 presents the ranking of the various health symptoms that serve as indicators of poor indoor air quality. Table 9 shows that the respondents ranked fatigue (with RII= 0.81) as the most reoccurring health symptom. Also, it is observed that only symptoms like fainting and nausea had a relative importance index of less than 0.6, indicating that they are not commonly observed symptoms. Also, from the mean values, it can be deduced that the values were closer to the Likert weighting of four, indicating that the respondents' general opinion was that the symptoms indicated poor indoor air quality.

HVAC and combustion-related factors that alter laboratories' indoor air quality
The questionnaire also sought the opinion of the respondents concerning how the heating, ventilation and air conditioning (HVAC) system, as well as combustion, contribute to the poor indoor air quality of laboratories. The respondents' opinions and ranking thereof are presented in Table 10. Table 10 shows that overcrowding in labs (RII=0.91) was ranked the first cause of poor indoor air quality. This is followed closely by combustion activities (RII=0.89). It can also be seen that other factors, such as faulty burners, too-humid air, and unvented combustion, though factors, did not have an intense effect owing to their relative importance indexes (RII), which are below 0.6. Regarding the mean, it can be observed that the values were closer to the weighting four (4), indicating that the respondents' opinion was that the identified factors are all causes of poor indoor air quality. Table 11 gives the respondents' ranking of the various remedial measures for the poor indoor air quality identified. It also provides the percentage with response per option and the mean. Table 11 shows that the respondents' highest-ranked remedy to the poor indoor air quality is the provision of adequate heating, ventilation and air conditioning systems (RII= 0.87). Also, from the mean values, it can be observed that, in general, the respondents opined that the identified remedy were all feasible options as the mean value is closer to the Likert weighting of four.

Discussion of Results
The discussions are based on the experimental survey of the laboratories under study. The study revealed that combustion-generated indoor air pollutants in the laboratory were more CO and NOx (Table 4); the mean value of SO was within the normal range as specified by the ASHRAE 62 and within the requirements for WHO and FEMA limits. However, the limit for pollutants like CO was above the limit specified by this standard, thus making exposure to such gaseous pollutants very hazardous to the health of both the students and the staff. Results of the measure (Tables 1 to 4) reveal that during the combustion activities, the amount of CO increases far beyond the NAAQS standard of 9ppm for all the labs except the Master's lab, where a water bath is used as a source of heat generation as against others that used gas burners. Also, from the result, it can be observed that the multi-purpose chemistry lab had the highest amount of pollutants owing to the population of students and the non-functional fume hoods. Also, from the experimental results, it can be established that the laboratory oxygen level was at the critical limit (20.9%), with the value dropping at specific points. This can account for the incomplete combustion leading to the massive generation of CO (up to 45ppm), which is far beyond the limit (9ppm).

Conclusions and Recommendations
The following can be concluded from the results of the experimental work and questionnaire survey undertaken in the research. The major reoccurring pollutant during combustion activities exceeds ASHRAE provision for a working area in CO. To a large extent, other pollutants are present but at a bearable level. Carbon monoxide is dangerous because it inhibits the blood's ability to carry oxygen to vital organs such as the heart and brain. Inhaled CO combines with the oxygen-carrying haemoglobin of the blood and forms carboxyhemoglobin (COHb) which is unusable for transporting oxygen. Combustion activities are practically unavoidable in teaching and learning practical science courses. The primary source of heat for the combustion activities is the gas burner, except in a few cases of a limited gas supply when the water bath is used as an alternative heat generating source.
Fatigue is one of the most reoccurring health symptoms of poor indoor air quality due to combustion activities. However, other health symptoms are headache, dryness and irritation, sinus congestion, blurred vision, sneezing, and chest pain.
The study recommends that Lab managers should pay proper attention to maintaining the laboratories' Heating, Ventilation, and Air Conditioning (HVAC) systems, particularly the fume hoods. It is also recommended that a fume hood be installed in the laboratories without the fume hoods, such as Chemistry Lab I, where there are no fume hoods. This is to take care of the gaseous pollutants from combustion activities.
As a matter of urgency, the school authority should try and construct new laboratories to address the overcrowding challenges in the laboratories that have intensified the effect of combustion activities which in turn affect the indoor air quality. This would also help accommodate the learning and teaching of the students