1. Introduction
It determines the breathable air standards of the environment in which quality of life and human life are found. These standards should be proportional to the breathable air conditions. These standards, especially in indoor environments, increase in degree of according to need. Home, school, the cinema, the library, workplaces, etc. are closed environments. Indoor air quality is essential in these environments, as that is where most of the time is spent. Today, indoor air quality is just as important as outdoor air quality. The air quality of our environments deteriorates due to environmental or personal reasons. There are some parameters that deteriorate the air quality of the environments we live in and threaten human and animal life.
The globalization of the world has increased the mobility of living organisms and rapidly diminished their naturalness. Vehicles and industry have increased significantly while forests have decreased. Under the name of urbanization, the natural balance has begun to deteriorate. Of course, such effects have changed the air quality considerably. All of these exist for humans and have reduced the standard and duration of human life. The degradation of the natural equilibrium has had an immediate impact on the air quality. The atmosphere one tries to live in has replaced breathable air. Increase in consumption, decrease in energy resources, lack of or inability to use renewable energy resources, etc. are among the many factors affect air quality, as well as the level of civilization in civilized societies. Societies that do not work for their health, no matter how productive and hardworking they are, will not be successful as long as they progress in an unhealthy way. In this direction, air quality is also essential. Some atmospheric effects and natural events can also deteriorate quality of the air, which is suitable for human degeneration. Efforts should be made to prevent these effects, and the danger’s dimensions should be minimized. Because childhood, a critical period in human life, can be vulnerable to this danger, children in the developmental stage, the most affected group, should finish their stages healthy so that they do not face severe problems in their later years, and any threatening factors should be minimized. Some parameters in the polluted air are carried to the human body for different reasons and cause serious health problems. Of course, coal consumption due to heating, industrialization, and public vehicles is among the critical effects in some periods that deteriorate the air quality. For these and similar reasons, poor air quality could not be a new effect today, and it was a problem that had a significant impact even in the Middle Ages. With the Industrial Revolution of the 18th and 19th centuries, the use of coal increased in cities. Urban smog appeared at one time under foggy weather conditions and caused great harm to human health. The increase in these and similar situations prompted countries to implement relevant legislation and take the necessary measures. The indoor environments we are in are called indoor environments. Pollutant factors affect the air quality here, such as the properties of the building, the equipment used and its derivatives, cigarette smoke, the atmosphere carried through the open window, etc. They are brought into the indoor environment through different sources and can adversely affect the quality of life.
Even if it is assumed that people use 4% of the oxygen in the air and breathe 12 m3 of air per day on average, this amount may decrease due to the environmental conditions they are in or be transported inefficiently to the human body. Of course, the increase in the quality level of our environment is directly proportional to our knowledge, skills, and experience. Ventilation time and shape are essential in our indoor environments. In determining indoor air quality, it is necessary to bring people to a healthy life, predict the stages that can be reached in this direction, plan cities, conduct industrial studies that directly affect such areas, etc. Indoor air quality can be kept under control by following an easy method.
Heavy metals are among the most harmful environmental pollutants due to their widespread use. Heavy metals are expressed as metals with a density greater than 5 g/cm
3. In medicine, heavy metals are defined as all metals with toxic properties, regardless of the atomic weight of the elements. Although more than sixty elements can be given as examples of heavy metals, the most common and well-known are mercury (Hg), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), cadmium (Cd), arsenic (As), chromium (Sn), lead (Pb), silver (Ag), and selenium (Se) [
1,
2,
3,
4]. These elements, which can show high toxic effects even at low concentrations, can be taken into the human body in various ways, and their products can cause serious health problems.
In Düzce province, dust samples were collected at different locations in order to explain the regional pollution distribution and various emission sources. Because children are more sensitive to air pollutants, the indoor and outdoor environments of primary schools were selected for sampling. PCB levels were determined in dust samples collected from indoor and outdoor environments of the primary schools in Düzce. PCB analyses were performed using the gas chromatograph/mass spectrometer (GC/MS) instrument. High ∑PCB concentrations in indoor samples show that the contribution of indoor sources and the effect of accumulation in indoor environments by transport from outdoor environments are greater [
5].
In Zgłobicki and Telecka, the levels of hazard index and cancer risk for Cd, Cr, Cu, Ni, Pb and Zn contained in street dust collected in 2013 and 2018 at 62 points located in different parts of a small/medium-sized city (Lublin, E Poland) were assessed. Heavy metal contents were analyzed by means of XRF spectrometry. For all metals except Cr, the health risk was higher in 2013 than in 2018 [
6].
In the study by Tou et al., seven road dust samples were collected from different regions in Shanghai, China, and analyzed in terms of total metal concentrations, particle element composition, ratios, morphology, composition, and crystalline phases. In general, road dust particles were characterized by high concentrations of Fe, Ti, Al, Cr, Ci, V Ni, Cu, Zn, Sn, and Sb. Four potential metal sources were identified using PCA analysis, including natural sources, exhaust and non-exhaust emissions, and vehicle electronics. The bulk elemental ratios of Ti/Nb, Ti/Al, Ti/Fe, Pb/Nb, Sn/Nb, and W/Nb in the road dust samples were higher than the corresponding reference ratios, indicating that the road dust was contaminated with Ti, Pb, Sn, and W. Anthropogenic Ti, Pb, Sn, and W were estimated by mass balance calculation and varied between 0.25 and 1.48 × 10
6 μg kg
−1, 0.19 and 1.21 × 10
5 μg kg
−1, 0.98 and 4.22 × 10
4 μg kg
−1, and 0.12 and 1.01 × 10
4 μg kg
−1, respectively. The concentration of NPs was determined by SP-ICP-TOF-MS and was 0.66–3.3 × 10
10 particles per g for Ti-containing NPs, 0.23–1.51 × 10
10 particles per g for Pb-containing NPs, 0.28–3.10 × 10
9 particles per g for Sn-containing NPs, and 1.34–9.38 × 10
8 particles per g for W-containing NPs, respectively [
7].
In a study by Bussan et al.,sediment samples were collected from seven locations around Calcasieu Parish, and the concentrations of Al, Cr, Cu, Fe, Mg, Mn, Ni, Pb, and Zn were determined by ICP-OES. The locations were selected due to their proximity to industrialized locations. None of the sampled sediments exceeded the Louisiana Department of Environmental Quality regulations. All sampled locations had higher concentrations when compared to a non-industrialized location in the area. These differences may have been caused by anthropogenic factors [
8].
In the study by Alotaibi et al., the occurrence of HMs in indoor and outdoor dust samples of an elementary school’s environment in Riyadh, Saudi Arabia, was reported, and associated potential human health risks were estimated. Dust samples were collected from outdoor and indoor environments at eighteen elementary schools using a soft plastic brush. The mean concentrations of Cd, Co, Cu, Ni, Pb, and Zn in collected indoor dust samples were much higher (0.08, 3.45, 59.20, 15.20, 4.99, and 94.10 mg kg
−1, respectively) than those of outdoor dust samples (0.07, 3.07, 42.20, 13.60, 4.57, and 62.40 mg kg
−1, respectively), due to fan operation, opened windows, and resuspension of dust by children’s activities [
9].
Indoor pollutants are a constant presence in our existence. Obviously, the greatest threat is faced during the periods of childhood. The health factor is critical, especially for our children who spend most of their time in school. In this direction, it is necessary to take measures against indoor air pollutants that threaten their health. For this reason, a study was carried out that included preventive and regulatory standards for our children, who are a high-hazard group according to indoor dust exposure times. Heavy metals, the group that poses the highest health risk in indoor dust, have been investigated.
2. Material and Methods
In this study, dust samples were collected from selected educational institutions in three different districts of the province of Konya (Meram, Selcuklu, and Karatay) in November 2018 and March 2019, taking into consideration seasonal variations. Environmental dust and heavy metal measurements were carried out during normal teaching activities in 15 schools in Konya. Samples were collected from classrooms, usually in any classroom on the middle floors, at fifteen minute intervals with the windows closed. Dust samples were collected with Gilian 5000 branded devices (Alka Lab., İstanbul, Turkey). “The General Methods for Ambient Dust Measurements for Sampling and Gravimetric Analysis of Respirable and Inhalable Dust-MDHS 14/3” method was used. “Metal & Metalloid Particulates in Workplace Atmospheres (Absorption)” (OSHA ID 121) measurements in ambient heavy metal cadmium (Cd), aluminum (Al), arsenic (As), lead (Pb), zinc (Zn), chromium (Cr), mercury (Hg) are used.
Filter papers used in the sampling were sent to Alka Environmental Laboratories. First, the metals were taken into solution using the wet filter paper burning method. Then, after the pH of the solution was adjusted, concentration values were found against the standards in the ICP-OES device (Alka Lab., İstanbul, Turkey), and calculations were made in mg/m3 according to the air sample taken. For indoor dust and heavy metal measurements, Sensidyne brand Gilian 5000 model (device code and serial number C141/2010303004) (Alka Lab., İstanbul, Turkey) and Sensidyne brand Gilian 3500 model (C58/A-20061201022 device code and serial number) (Alka Lab., İstanbul, Turkey) devices and equipment were used.
In this study, samples were collected in the educational institutions determined by considering some characteristics and sent to the laboratory for the results. While evaluating the incoming results, an evaluation was made by taking into account some characteristics of the classes in which the measurement was made. These features include the size of the classroom, the area characteristics of the classroom, the type of ventilation, the physical features of the building, etc. The amount of air per capita was determined, and the reasons that hindered this amount were determined by considering the characteristics of the class. In addition, the results were interpreted by considering the economic and socio-cultural effects, population, proximity to industry, and the connection of schools with the streets of the districts.
3. Results
During the visits, certain characteristics were determined in the classrooms in order to collect samples in the designated regions. In light of these characteristics, interpretations of the analysis results were made. In classroom ventilation, calculations are made based on the classroom’s population and a number of physical parameters. The need for outside air can be determined based on the existing area. In this direction, the volumes of the classes we determined among the educational institutions were calculated, and the required air quantities were found based on the number of people. The conclusion and recommendations section includes necessary interpretations according to our laboratory results. By using these calculations, a formula suitable for the subject and the required amount of fresh air for the number of people can be calculated and compared with the analysis results.
Table 1 shows the amount of fresh air people need in some environments and the given space volumes.
Data on the physical properties of the measured classes are given in
Table 2.
The meteorological conditions of the measurement date are shown in
Table 3, and the dust measurement results are shown in
Figure 1 and
Table 4.
Since the measurement result obtained for short-term dust measurement at 15 points under normal teaching conditions in the facility is not limited, no evaluation was made. The measurement results can be used to give an idea of what to expect in risk assessment studies. In line with the Dust Fighting Regulation published in the Turkish Official Newspaper No. 28812 on 5 November 2013, which was prepared based on Article 30 of the Occupational Health and Safety Law No. 6331, the limit value for personal exposure to total dust is 15 mg/day in Annex 1. The limit value for m3 and respirable dust is given as 5 mg/m3. When our values are based on 15 mg/m3, only two of our schools (e and p) are close to this value. Others are below the limit value. Among the most important reasons for these results being below the threshold value are the weather conditions and, accordingly, insufficient ventilation times.
The second measurements were made in March 2019. The seasonal weather report for that period is given in
Table 5, dust sample results are given in
Table 6, and dust measurement results are given in
Figure 2.
National and international boundary values are given in
Table 7. Accordingly, the TWA (time-weighted average) value among national values is the time-weighted average of the allowable concentration of chemical substances that does not impair the individual’s health for a maximum reference period of eight hours for persons working in closed environments. Acute toxic symptoms occur when this value level, which is used for chemicals with more toxic (poisoning) effects, is exceeded. When looking at the international limit values, there are names specified, such as OSHA and NIOSH. OSHA (Occupational Safety and Health Administration) is a structure that was born as a result of the occupational health and safety operation in the United States of America in 1970. Subsequently, NIOSH was established as OSHA’s research and development branch. It covers the procedures to be protected from the hazards arising from the work or environment that the employer is legally obliged to follow with OSHA values. A risk analysis was carried out for the learner and teacher based on heavy metals in indoor dust in educational institutions and these values.
The results obtained from the measurements made in schools and their comparison with the limit values are given below.
As shown in
Table 8, the measured heavy metal values for cadmium and arsenic were below the limit values. Therefore, when schools are examined, the increase in the amount of arsenic due to the drinking water used, containing cadmium, the use of batteries, and the provision of pigment properties with cadmium in oil paint derivatives causes this increase. According to OSHA values, one of the similar occupational health and safety organizations in the EU and the USA, the cadmium limit value is 0.05 mg/m
3. In this direction, a risk analysis has been made and preventive methods have been added, in order to aim to approach limited values. Likewise, drinking water and groundwater were examined for arsenic, which was well above the TWA value for OSHA. It is aimed to reduce it below the limit value for this parameter by performing a risk analysis. Elements with TWA values were below the limit values of Al, Zn, Hg, and Pb according to heavy metal measurement results.
Cadmium value has been exceeded according to OSHA standards and accordingly.
Among the pigments used in paints, the most dangerous one is cadmium, along with lead. It is used for yellow and red paints. It mostly affects the respiratory tract and causes important symptoms such as burning in the throat, coughing, and pulmonary edema. It manifests itself in the gastrointestinal tract as bloody vomiting and diarrhea. In the musculoskeletal system, chronic bone changes and related gait disturbances are observed [
11].
Short-term exposure to high concentrations of cadmium in the air causes symptoms such as malaise, fever, headache, and vomiting, as in the common cold. Long-term exposure to low-3 concentrations causes lung or prostate cancer, kidney damage, and hypertension. Cadmium is also thought to cause diseases such as pulmonary emphysema, bone disease, anemia, yellowing of the teeth, and loss of sensation [
12].
The risk analysis table created regarding the results obtained is given in
Table 9. Many factors negatively affect air quality conditions in classrooms. Reductions have been made. We should not forget that administrators, working staff, teachers, and students have separate duties and responsibilities for health and safety in the school or classroom, and applying improvements or measures by using methods of predetermining the risks should not be neglected. It should be done by companies authorized to conduct risk analysis. It should be renewed according to the danger class of the institution, and the employer should follow up. As an example, in the risk analysis table, measures to be taken to improve air quality in classroom environments in selected educational institutions and predetermined dangerous situations are given. It is possible to increase these steps.
4. Conclusions
Considering the measurement results, according to the results obtained from the measurements dated for the first period (November 2018) and the second period (March 2019), there have been changes in the dust measurement results. First, when the periods are examined within themselves, the winter–autumn seasonal conditions come to the fore in the first period. Seasonal differences make up an essential factor that causes pollutant parameters in the environment to vary. Using heaters, closing the windows, or not using the appropriate type of ventilation due to the heating caused by air cooling increases the amount of dust released into the environment. The rise in student movements in crowded classroom environments also supports this phenomenon. Schools—due to the presence of various indoor air pollutant sources; the inability to use quality building, flooring, furniture materials; and the failure to regularly maintain and repair these structures—are environments where indoor air quality is low.
Clean air per capita should be determined for schools and should be increased. Appropriate ventilation system design should be used, and this should be done with help from a specialist such as the Chamber of Mechanical Engineers. Considering the class size, the number of windows and doors, and the size of the area, the environment’s air quality can be improved and the fresh air flow per person can be increased by establishing a correct ventilation system. All kinds of dangers that may occur with education can be determined beforehand, and it may be possible to take precautions without increasing the risk dimensions. For this purpose, awareness-raising activities should be carried out on the issue of air quality, and students should be supported to act with awareness of this issue.
In our study, when the heavy metal measurement results were determined, it was determined that some heavy metals were above the limit values. When it is shown that the heavy metal arsenic is above the determined value, it has been determined that it is generally a problem caused by drinking water. Drinking water brought to the districts of Konya province is transported by transmission lines. Corrosive substances carried by the drinking water, which passes because of evaporation or sedimentation from the winter, can be effective, especially during transport in the summer. In addition, arsenic, which can mix with groundwater due to erosion, easily mixes into drinking water. It is taken into the body orally.
For arsenic removal, firstly, drinking water should be analyzed. Then, studies should be carried out to reduce the amount of arsenic. The water should be chlorinated, and this process should be started with ozonation. Arsenic removal is also possible with the filtration process. The reverse osmosis method will also be a different alternative for this process.
Symptoms of arsenic poisoning include severe abdominal pain, leg cramps, a metallic taste in the mouth, and cold and wet skin. Of course, acute or chronic poisoning can occur, and in these cases, medical assistance should be considered.
When the investigation shows that the cadmium heavy metal is above the boundary value, batteries, as well as the dye pigment used in the environment and the easy transportation of cigarettes smoked outdoors to indoors, can be given as examples. Since children are in the easily affected group, they will be exposed to poisoning on their own. Cadmium is a heavy metal that is taken into the body by mouth, inhalation, or skin contact. Excretion from the body is slow. Cadmium exposure can cause irritation in the nose and throat, dryness and cough, headache, chills, chest pain, and headaches. Long-term exposure can cause serious health problems such as kidney failure and respiratory failure. Tools such as batteries used in educational institutions should be kept away from children. In the use of paint materials, clean and environmentally friendly products should be preferred.
In this study, indoor dust and heavy metals were determined, and their effects on child health were investigated. The quality of the indoor air is affected by the air that can readily enter from the outdoors. The rapidly increasing population, unplanned urbanization, and increase in facilities and factories affect the air quality. The most important thing to do is to be conscious individuals and avoid all kinds of polluting factors that will threaten the health of children, adults, and living things. Indoor environments, where we spend most of our time, are the most important locations for the health of all of us, but they are also the primary areas where air quality should be high. In particular, we need to keep all polluting substances that will easily affect the health of our children away from them.