Objective This study aimed to investigate the prevalence and risk factors of chronic respiratory symptoms among school teachers in Gondar city, north-western Ethiopia.
Design A school-based cross-sectional study was conducted from April to May 2019. A self-administered British Medical Research Council Questionnaire was used to assess chronic respiratory symptoms. Data were entered into Epi Info V.7 and Stata V.14 was used for analysis. A multivariable logistic regression analysis was conducted to identify factors associated with chronic respiratory symptoms. The association was determined using adjusted OR (AOR) with a 95% CI at a value of p<0.05.
Setting The study was conducted in public and private schools in Gondar city.
Participants A total of 822 teachers participated in this study.
Outcome measures The primary outcome is the prevalence of chronic respiratory symptoms.
Results The total response rate was 97.4%. The majority, 532 (64.7%) of the participants, were male. The mean age (±SD) of the respondents was 36.69 (±6.93) years. The total prevalence of chronic respiratory symptoms in the previous 12 months among teachers in Gondar city was found to be 31.14% (95% CI 27.99% to 34.43%). A family history of respiratory problems (AOR=1.90; 95% CI 1.07 to 3.37), an overweight body mass index (AOR=2.57; 95% CI 1.57 to 4.21), exposure to secondhand cigarette smoke at home (AOR=9.85; 95% CI 4.77 to 20.33), use of chalk (AOR=1.97; 95% CI 1.25 to 3.09), and failure to open windows during class (AOR=2.15; 95% CI 1.02 to 4.52) were risk factors for chronic respiratory symptoms.
Conclusion This study concluded that the prevalence of chronic respiratory symptoms was high among teachers. Making a smoking-free zone, avoiding smoking in public places, improving the ventilation conditions of the classrooms and controlling the chalk dust are all necessary actions to take to reduce chronic respiratory symptoms.
- Respiratory tract tumours
- Respiratory physiology
- Respiratory infections
- RESPIRATORY MEDICINE (see Thoracic Medicine)
Data availability statement
Data are available upon reasonable request. All the data generated in this study are included in this manuscript. The data sets used and analysed to produce the current manuscript can be obtained from the corresponding author upon reasonable request via email address: email@example.com.
This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.
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- Respiratory tract tumours
- Respiratory physiology
- Respiratory infections
- RESPIRATORY MEDICINE (see Thoracic Medicine)
Strengths and limitations of this study
The study focused on subgroups of the working population at risk of chronic respiratory symptoms requiring immediate attention.
The study provides evidence from a large sample with very good response rates (97.4%).
The results might be limited by recall bias due to its reliance on participants' self-reported data.
Also, due to its cross-sectional design, this study could not show a temporal relationship.
Chronic respiratory diseases are a group of diseases that affect the lungs and make breathing difficult. They affect hundreds of millions of people of all ages and are a major cause of morbidity and mortality in every country.1 2 The prevalence of chronic respiratory symptoms is increasing everywhere, and in particular among children, the elderly and occupationally at-risk groups like school teachers.1 In developing countries, where poverty and non-communicable respiratory disease have long been linked, most patients have limited access to basic healthcare services, which end up with a high proportion of paediatric admissions and outpatient attendance.3 Another issue in developing countries is a lack of resources for health planners to develop potential prevention and control methods for respiratory diseases. Also, there are many gaps in the recognition and management of these disorders in the majority of developing nations, despite the existence of international guidelines for their diagnosis and management.4 If significant attention is not paid to them, these diseases will continue to constitute a serious public health burden on a global scale due to their frequency and economic significance.1 5
According to the 2019 Global Burden of Disease6 report, chronic respiratory diseases accounted for 2.91% of total disability-adjusted life years.6 Lung diseases caused by occupation and the environment are one of the world’s most serious problems. Respiratory disorders from occupational sources are major public health issues, accounting for up to 30% of all registered work-related diseases and 10%–20% of occupation-related deaths worldwide.7 8 Studies have been conducted to show the detrimental effects of occupational dust and particles on workers' respiratory function in different industries,8–10 as well as the impact of particular health problems on pulmonary function,11 but the burden of problems in educational sectors has been overlooked.
In many schools around the world, particularly in developing countries like Ethiopia, classroom instruction using whiteboards and chalk still predominates.12–15 A significant number of chalk dust particles with an aerodynamic diameter of less than 10 m are created during classroom instruction.16 Gypsum (a dehydrated form of CaSO4), calcite (CaCO3), dolomite and a trace amount of organic glue make up these inhalable particles,17 which are small enough to enter conductive airways and the lower respiratory system18 and cause harm to health. It is widely assumed that the particles may increase the risk of chronic respiratory symptoms by causing oxidative stress and inflammation.18–20
An investigation has revealed that shaking, using the duster frequently, using chalk for a longer time, and other conditions of usage are all directly related to an increase in the prevalence of wheezing, frequent respiratory infections, upper respiratory tract symptoms and aphonia.21 Excessive exposure to tiny particles of chalk could accumulate in the respiratory system, causing breathing difficulties and chest pain. The likelihood of developing an allergy to chalk dust is higher among exposed groups.22 Since chalk is a significant source of fine particulate matter in classrooms and chalk dust may be harmful to allergic people, resulting in laryngitis and breathing problems, teachers who use chalk and chalkboards are at risk of developing occupationally related pulmonary function impairments.23 Teachers are more likely to experience chronic respiratory symptoms as a result of their occupational exposure.24
A range of risk factors has been associated with the occurrence of chronic respiratory symptoms among teachers. Sex, age, educational level and work experience were the identified demographic factors associated with respiratory symptoms.24 Exposure to harmful gases, biomass, tobacco smoke in the home, poor housing conditions and crowding have also been identified as causes of respiratory disease.24 25 Moreover, teachers are exposed to various environmental hazards at school that affect indoor air quality (IAQ).26 Dense school occupancy, high-insulation building materials, aeroallergens (mould, dust mites), pests (cockroaches, rodents), volatile organic chemicals from cleaning products, and shortages of school budgets, specifically in developing countries like Ethiopia, all contribute to an increase in respiratory problems in teachers.26–28
The majority of Ethiopian teachers are at risk for respiratory issues and work in deplorable conditions, being exposed to dust not only at work but also at home. In Ethiopia, there is also a high student-teacher ratio, which results in crowded classrooms and exposes both teachers and students to a variety of infections that can cause serious respiratory health problems. However, the scope of respiratory issues is unclear, as there are little data on these types of health problems and their risk factors among teachers in the country. To address these gaps, the present study was conducted to investigate the self-reported chronic respiratory symptoms and associated factors among public and private school teachers in Gondar city, north-western Ethiopia. This study contributes to a better understanding of the development of respiratory symptoms among teachers and helps to further develop preventive measures to reduce the frequency and severity of respiratory problems.
Methods and materials
Study design, period and area
A school-based cross-sectional study was conducted among primary and secondary school teachers from April to May 2019 in Gondar city, north-western Ethiopia. The city is located about 727 km from Addis Ababa, the capital city of Ethiopia, and 180 km from Bahir Dar, the capital city of Amhara Regional State. In 2019, the city’s total population is estimated to be 500 788, of whom 300 000 are male. In the city, there are 66 primary schools (44 public primary schools and 22 private primary schools) and 15 secondary schools (11 public secondary schools and four private secondary schools). Within these schools, there are 1771 primary school teachers (1382 public primary school teachers and 389 private primary school teachers) and 793 secondary school teachers (711 public secondary school teachers and 82 private secondary school teachers), bringing the total number of teachers in the city to 2564 (central Gondar zone education office, unpublished data, 2018).
According to reports from the central Gondar zone education office, due to a lack of resources to use modern dust-free instructional materials such as a whiteboard with a marker, both public and private schools in the city primarily used traditional instructional materials such as chalk and blackboard. Moreover, school teachers in the city were exposed to a variety of environmental hazards, including poor IAQ, the schools serving for long periods without renovation due to limited school funding, dampness and mould, and pests in schools. The majority of teachers work both shifts, there are many classes taught, and the number of students in each class exceeds the national guidelines due to the restricted number of teachers in the country. These and other unfavourable indoor environmental conditions could exacerbate the chronic respiratory problems of school teachers in the city.
Source and study populations
All public and private school teachers in Gondar city were the source population. The study population for this study was all public and private school teachers who worked in selected schools.
Inclusion and exclusion criteria
Teachers who had worked at a selected school for more than a year were included in this study, whereas teachers who had a history of asthma, a history of chest injuries, chest surgeries, cardiac disease, tuberculosis (TB) or other respiratory disorders diagnosed by a physician before starting work were excluded because they could potentially bias the results of our study.
Sample size determination and sampling procedure
The sample size was calculated using a single population proportion formula,29 with the following assumptions: a 5% margin of error (d), a proportion (p) of a respiratory problem among school teachers of 50% (no previous study in a similar context) and Zα/2=the value of the standard normal curve score corresponding to the given CI. Accordingly, based on a single population proportion formula: ; where n=initial sample size, Zα/2=1.96 corresponding to 95% confidence level, p=proportion =50%, d = margin of error =5% = 0.05; =384. Adding 10% for the non-response rate resulted in 10% of 384 equal to 38.4≈38. When considering the design effect, the calculated sample size was multiplied by the design effect to correct the estimated sampling variance. So, the overall sample size for this study was (384+38) *2=844 school teachers.
A multistage sampling technique was used in this study. First, schools were divided into two categories: public and private. The schools were then divided into two groups: elementary and secondary schools. To ensure representativeness, 13 (20%) of 66 elementary schools and 3 (20%) of 15 secondary schools were chosen using a simple random sampling technique. To be more specific, 9 (20%) of 44 public primary schools, 4 (20%) of 22 private primary schools, 2 (20%) of 11 public secondary schools and 1 (20%) of 4 private secondary schools were selected using the lottery method, and the calculated sample was proportionally allocated to all selected schools. Finally, study participants were selected randomly using computer-generated random numbers from designated schools using the list of teachers obtained from the human resource department as a sampling frame.
Variable measurement and definition of terms
Chronic respiratory symptom
It was the primary outcome variable in our study and was measured using a standardised British Medical Research Council (BMRC) Questionnaire. It was counted if teachers reported one or more symptoms such as chronic cough, chronic phlegm, chronic wheezing, chronic shortness of breath or chronic chest tightness that lasted at least 3 months in the past year.30
The experience of a cough for most days of the week (≥4 days) for at least 3 months in 1 year.31
We considered someone to have phlegm if they had sputum expectoration on most days of the week (5 days) for at least 3 consecutive months in the last 12 months.31
A condition causing a wheezy or whistling sound to be heard during inhalation or exhalation (for at least 3 months in a year).31
Chronic shortness of breath
A feeling of discomfort or difficulty breathing during various activities, such as walking up a slight hill, dressing or undressing, or walking slower than peers on level ground (walking at their own pace) for at least 3 months at a year.32
Chronic chest pain/tightness
Chest pain that has kept teachers from work in the past year.31
Body mass index
Weight in kilograms divided by the square of the height in metres (kg/m2), categorised as underweight = body mass index (BMI) <18.5, normal= BMI =18.5–24.9, overweight=BMI ≥25.33
Teachers who have never smoked a cigarette before.31
Teachers who had quit smoking at least 1 year before the survey.31
Teachers who smoked at the time of the study or had stopped smoking less than 1 year before.31
Secondhand cigarette smoker
Teachers who inhale the smoke released from the burning end of a cigarette (or other burned tobacco product) between puffs (sidestream smoke) and who inhale the smoke exhaled by other smokers (exhaled mainstream smoke).34
Teachers who have never consumed alcoholic beverages, including locally brewed beverages.35
Teachers who consumed alcohol no more than once in the past 12 months.35
Teachers who consumed any kind of alcohol one to four times per week.35
Chewing khat three times a week for at least 12 months.36 37
Doing physical exercise
Doing any kind of sports activity at least two times per week with a duration of at least 30 min.38
Family history of chronic respiratory diseases
The presence of one or more of the chronic diseases of chronic bronchitis, TB, heart disease, chronic sinusitis, asthma and lung cancer in either of the natural parents (mother or father) and identified by physicians.39
The presence of a window
An open window during working hours.
Is measured as the area of the classroom divided by the number of students in the class (m2/number of students in the class) and classified as crowded if the area of the classroom per number of students is less than 1.4 m2, otherwise uncrowded.40 41
Good ventilation conditions
The ventilation condition of the living home was reported by the participants, and the presence of functional mechanical ventilation systems (ventilator, local exhaust ventilation system) and natural ventilation systems (doors, windows and any other openings) in the living home was classified as good ventilation conditions.42
Poor ventilation condition
The absence of functional mechanical and natural ventilation systems in the living home, as well as the obstruction of airflow by adjacent buildings.42
An infestation of cockroaches in a house caused by broken drains, building defects and areas that provide dark harborages such as under stoves, behind refrigerators, and near food and water, where cockroach allergies are common triggers for respiratory problems.43 44
Data collection tools and procedures
Data were collected using a pretested and self-administered standardised BMRC Questionnaire. The questionnaire was adapted and modified after the investigators reviewed various related literature based on the study objectives.26 30 31 39 40 45 46 The questionnaire was originally designed in English and then translated into an Amharic version, the local language of the study area, by authors and language experts. The questionnaire was divided into five sections (see online supplemental file 1). The first section focuses on sociodemographic factors such as school type, age, gender, educational status, teaching experience, monthly salary, household members in person and family history of respiratory problems.
The second section of the questionnaire focused on the assessment of chronic respiratory symptoms in teachers and was collected using the BMRC Questionnaire. The BMRC Questionnaire is recommended for use in epidemiological and occupational respiratory surveys as well as in consultations for respiratory symptoms or lung function assessment. The symptoms of chronic respiratory symptoms in this study included chronic cough, chronic phlegm, chronic wheezing, chronic shortness of breath or chronic chest tightness. The survey tool has been validated and widely employed to assess chronic respiratory symptoms in different settings and is a reliable and accurate method of collecting such evidence.31 47 48 The instrument was also repeatedly used in Ethiopian studies, which were tailored to the local culture and conditions.8 10 31
The third part of the questionnaire includes information used to assess behavioural characteristics such as BMI (kg/m2), substance use (cigarette smoking, alcohol consumption and khat chewing), secondhand cigarette smoke (parents/others) and physical activity. The fourth section contains questions designed to collect information on the teachers' household air pollution and housing characteristics, such as the type of fuels used for cooking, the location of cooking, the distance of the household residence from the main road, the type of household residency, the presence of cockroaches in the household, the presence of livestock in the home (eg, cattle, pigs, goats, sheep or poultry), and the household waste disposal mechanism.
The final section of the questionnaires focused on the respondents' specific work environment attributes, including work shift, working hours/day, materials used for writing on the board, window condition when teaching, frequency of classroom cleaning per week, presence of visible mould in the classroom, crowdedness of the classroom and types of school environment construction materials. Finally, the self-administered Amharic version of the questionnaire was distributed to all eligible participants at their workplaces (schools). A4 papers, pens, pencils, a personal computer, a phone and a notebook were used to capture the data.
Data quality assurance
To ensure the quality of the data, we gave much emphasis to the appropriate design of data collection tools. The questionnaire was first developed in English and translated into Amharic and back to English by language experts and physiologists to ensure consistency. Second, we employed two BSc environmental and occupational health and safety data collectors and an MSc environmental health supervisor who had prior experience and knowledge of the data collection process. Data collectors and supervisors took 2 days of training on issues relating to the clarity of the questions, objectives of the study, procedures, techniques, research ethics and data collection methods, as well as the roles and responsibilities maintained by both the data collectors and supervisor during the data collection process. The role of the data collectors was to distribute the questionnaires to eligible participants and collect the filled-out questionnaires from them, while the supervisor’s responsibility was to assist the data collectors on how they were recruiting the study participants, how they were maintaining the confidentiality of the participants, checking the collected data were correctly filled out, and providing advice for the data collectors if there were problems during the data collection process. Additionally, the principal investigator consistently supervised both the data collectors and the supervisor. Third, we conducted a pretest 1 week before the actual data collection period on 5% of the questionnaires (on 42 teachers) in the Kolla Diba town secondary school, nearby Gondar city, to check the response, language clarity, appropriateness and consistency of the instrument. Based on the findings of the pretest analysis, we modified some words and misinterpretations, reduced the number of questions without affecting what was intended to be measured, and made corrections to the ambiguous questions. Problems encountered during the data collection process were resolved through on-the-spot discussions with the principal investigator, supervisor and data collectors.
Data management and statistical analyses
Each questionnaire was checked for completeness and consistency daily. The collected data were manually entered into Epi Info V.7 software (Centers for Disease Control (CDC), Atlanta, Georgia, USA) for cleaning, editing, coding, and checking for missing values and exported into SPSS V.20 software (IBM Corporation, Armonk, New York, USA) for further analysis. Descriptive statistics were calculated using frequency, percentage, mean and SD. Descriptive statistics were computed and presented using frequencies, percentages, means, SD, tables and graphs. Multicollinearity among independent variables was assessed using variance inflation factors (VIF) and found to be acceptable (all variables had VIF<5 values). The reliability of the questionnaire was tested using Cronbach’s α, and the value of the α coefficient was found to be 0.85. As a result, the internal consistency of the questionnaire in reproducing what had previously been measured using the instrument was considered acceptable. A bivariable and a multivariable binary logistic regression models were fitted to identify the factors associated with chronic respiratory symptoms. To control the effects of potential confounders, significant variables with a value of p<0.2 in a bivariable logistic regression analysis were exported to the multivariable logistic regression model using the enter variable selection method. The Hosmer-Lemeshow test was used to check model fitness, and we found the model to be a good fit (p=0.7380).49 Finally, a statistically significant association was declared at a cut-off of p<0.05 and an adjusted OR (AOR) with 95% CIs to establish the strength of associations in the multivariable logistic regression model.
Patient and public involvement
School teachers participated in this investigation by contributing useful information. However, they have never been involved in the study design, protocol, data collection tools, reporting or dissemination of the findings. The findings of the study will be shared with the Gondar city education office as well as through open-access publication.
Sociodemographic characteristics of respondents
A total of 844 questionnaires were distributed; 822 completed and valid questionnaires were analysed, corresponding to a response rate of 97.4%. The majority, 532 (64.7%) of the study participants, were male. The mean age (±SD) of the respondents was 36.69 (±6.93) years. More than three-quarters, 624 (75.9%) of the respondents, had a bachelor’s degree (BSc/BA), and 331 (40.2%) of them had been working for 6–10 years. About a quarter, 192 (23.4%) of the participants, stated that their households included five or more people. Regarding the participants' family history of respiratory diseases, 67 (8.2%) of the participants reported that their family had a history of respiratory diseases such as asthma, emphysema and TB (table 1).
Behavioral characteristics of respondents
The majority of respondents, 687 (83.6%), had a normal BMI (18.5–24.9 kg/m2), while 94 (11.4%) of them were overweight (BMI>18.5 kg/m2). Thirty-one (3.8%) of the participants were current smokers, 55 (6.7%) were former smokers and 736 (89.5%) had never smoked, while 54 (6.6%) and 3 (0.4%) of them were exposed to cigarette smoke at home and school, respectively. Regarding the physical activity of the respondents, 322 (39.2%) of them reported engaging in physical activity at least twice a week (table 2).
Household air pollution and housing characteristics of the respondents
The majority, 462 (55.9%) of respondents, used unpurified energy sources (39.1% biomass and 16.8% charcoal) for food preparation, and more than half, 437 (53.2%) of them cooked indoors. Among indoor cookers, 182 (41.6%) of the participants used unpurified energy sources, including biomass and charcoal. The majority, 607 (73.8%) of the respondents, lived more than 100 m from the main road. Regarding housing conditions, 437 (53.2%) of the respondents reported living in a house made of mud and wood. The majority, 700 (85.2%) of the participants, reported that their house was in poor ventilation condition. Nearly a third, 268 (32.6%) of participants, reported that their house was infested with cockroaches. Of the respondents, 58.8%, 37.2% and 4% reported that they disposed of their household waste by burning, dumping in the open and burying, respectively (table 3).
Work environment-related characteristics of the respondents
Three hundred and fifty-four (42.7%) of participants worked between 5 hours and 6 hours per day, and a third (33.7%) of participants worked more than 6 hours per day. When comparing the use of chalk and markers for writing on the board, 113 (13.8%) of the participants used chalk. Almost all of the participants, 783 (95.3%), open the classroom windows while teaching. One hundred and forty-three (17.4%) of the participants reported that the classroom had visible mould, and 760 (92.5%) of them taught in a crowded classroom (table 4).
Prevalence of chronic respiratory symptoms
The overall prevalence of chronic respiratory symptoms among sampled teachers in Gondar city during the past 12 months was 31.14% (n=256) (95% CI 27.99% to 34.43%). Chronic shortness of breath 20.1% (n=165) (95% CI 17.4% to 23.0%); chronic cough 18.7% (n=154) (95% CI 16.1% to 21.6%); chronic wheezing 13.3% (n=109) (95% CI 11.0% to 15.8%); chronic chest tightness 11.20% (n=92) (95% CI 9.1% to 13.5%); and chronic phlegm 10% (n=82) (95% CI 8.6% to 12.3%) were the most frequently reported respiratory symptoms (figure 1). There was a significant difference in the prevalence of the symptoms between men and women (23.0% and 8.14%, respectively). Table 5 shows the result of the χ2 test. The value of p obtained was <0.001 (χ2=13.5073), showing a significant association between chronic respiratory symptoms and sex difference. The calculated OR (OR=13.51, 95% CI 3.28 to 31.19) showed that male respondents were 1.83 times more likely to have chronic respiratory symptoms compared with female respondents.
Factors associated with chronic respiratory symptoms
Bivariable and multivariable logistic regression analyses were performed to identify factors associated with chronic respiratory symptoms. School type, age, marital status, teaching experience, size of household members, chronic respiratory problems in the family, BMI, cigarette smoking, secondhand cigarette smoke at home, type of residence, presence of cockroaches in the home, working hours per day, materials used for writing on the board, opening windows during class and the presence of visible mould in the classroom were the factors associated with chronic respiratory symptoms in the bivariable binary logistic regression analysis. However, after controlling for confounding variables in the multivariable binary logistic regression analysis, a history of chronic respiratory problems in the family, an overweight BMI, exposure to secondhand cigarette smoke at home, use of chalk and failure to open windows during class were found to be significant factors associated with chronic respiratory symptoms among sampled school teachers in Gondar city, north-western Ethiopia.
The likelihood of suffering from chronic respiratory symptoms was twofold higher among teachers whose families had respiratory problems than among teachers whose families did not have these problems (AOR=1.90; 95% CI 1.07 to 3.37), with a value of p=0.029. The incidence of chronic respiratory symptoms was also significantly influenced by BMI in overweight individuals. Teachers with an overweight BMI (>18.5 kg/m2) were 2.57 times more likely to develop chronic respiratory symptoms than teachers with a normal BMI (18.5–24.9 kg/m2) (AOR=2.57; 95% CI 1.57 to 4.21), with a value of p<0.001. In addition, teachers exposed to secondhand smoke at home had a 10-fold higher risk of developing chronic respiratory symptoms than teachers not exposed to secondhand smoke at home (AOR=9.85; 95% CI 4.77 to 20.33), with a value of p<0.001. Also, teachers who taught with chalk had twice the risk of developing chronic respiratory symptoms than those who used markers (AOR=1.97; 95% CI 1.25 to 3.09), with a value of p=0.003. Moreover, opening the windows during class had a significant effect on the occurrence of respiratory symptoms in this study. Teachers who did not open windows during class had a 2.15 times higher risk of chronic respiratory symptoms than those who did (AOR=2.15; 95% CI 1.02 to 4.52) with a value of p=0.043, as shown in table 6.
In the educational services industry, work-related illnesses and injuries have not been well documented.50 While poor environmental conditions in schools have been well documented and characterised, it is less certain how widespread respiratory health issues are among school personnel.26 51 Teachers and other employees who work in schools in Ethiopia are disproportionately affected by respiratory problems.28 52 To our knowledge, this is the first study quantifying the proportion and factors influencing respiratory symptoms among teachers employed in the educational services sector in Ethiopia. Accordingly, the prevalence of respiratory symptoms among public and private school teachers in Gondar city during the previous 12 months was 31.14% (n=256) (95% CI 27.99% to 34.43%). A family history of respiratory problems, an overweight BMI, exposure to secondhand cigarette smoke in the home, the use of chalk and opening classroom windows were risk factors for the occurrence of chronic respiratory symptoms.
The current study had a higher magnitude compared with the studies conducted in Chennai, India (10%)48 and the study from school teachers in Shimla, India (28.35%).25 The difference might be due to the sample size variation between the countries; the previous study conducted in Chennai was conducted among a small number of participants (n=100 teachers) compared with the number of participants in this study (n=822 teachers). The inconsistencies could also result from differences in data collection methods and reporting practices for work-related diseases between the nations. In earlier studies, data were measured using both subjective (self-report) and objective (pulmonary function test) methods, whereas the current study only uses subjective measurement (a self-administered questionnaire).25 48 Due to the possibility of predicted recall bias, there might be an overestimation or underestimation of the condition in self-reported measurement. The other plausible reason for the increased chronic respiratory symptoms in the current study could be the crowdedness of the classroom. The majority (92.5%) of the teachers in the study taught in a crowded classroom. Theoretically, overcrowding could increase the risk of respiratory illnesses by increasing the likelihood of teacher-student cross-infection.53 54 Differences in IAQ in schools and home environments,26 classroom environmental conditions,51 climatic circumstances,55 56 and teachers’ perception, knowledge, and attitude about the school environment concerning respiratory health issues,57 the level of socioeconomic status, the presence of other complement symptoms, lack of sanitation and poor infrastructure, the data collection period, and sampling techniques used were further elements that could explain the difference in the prevalence of respiratory health problems between the nations.
The findings of this study revealed that the chronic respiratory symptoms reported were chronic shortness of breath (20.1%), chronic phlegm (10%), chronic chest tightness (11.20%), chronic wheezing (13.30%) and chronic cough (18.70%). This study’s findings were lower than those of a Malaysian study, which found that cough (13.1%), phlegm (21.3%), wheezing (26.2%) and shortness of breath (47.5%) were all common.58 Our findings, however, were higher than those of a Romanian study, which discovered wheezing (3.85%), chest tightness (6.73%), shortness of breath (1.92%) and coughing up phlegm (6.73%).26 The difference could be the result of the data collection technique, sample size and measurement tool. Studies conducted in Malaysia and Romania were conducted among 61 and 104 teachers, respectively. In contrast, the current study had a sizeable sample size (822 teachers). Regarding the measurement tool used, this study employed a BMRC Questionnaire to evaluate the chronic respiratory symptoms of school teachers, whereas investigations in Malaysia and Romania used American Thoracic Society Questionnaires. On top of that, the other possible explanation for the difference might be the variation in a study setting, ventilation system, age of the school building, materials used for writing on the board (chalk or marker), teacher-to-student ratio, location of the school (away from the street or schoolyard for exposure to traffic or other sources), type of floor, the indoor and outdoor air quality of the school environment, and classroom construction materials.26 59–61 Furthermore, this distinction may account for differences in culture, belief, and living and earning conditions between countries.
This study found a substantial correlation between a family history of respiratory problems and chronic respiratory symptoms. Teachers whose families had respiratory problems had a twice higher risk of developing respiratory symptoms than teachers without such problems. This result was consistent with a previous study in Ethiopia,39 India45 and Thailand.62 This could be because genetics plays a role in the development of chronic respiratory symptoms. While environmental factors influence disease progression, it has long been recognised that asthma, bronchiectasis, cystic fibrosis and emphysema (α-1-antitrypsin deficiency) are heritable, with genetic factors playing a significant role in the risk of developing respiratory problems.63 64
This study also indicated that teachers with an overweight BMI (>18.5 kg/m2) were 2.57 times more likely to develop chronic respiratory symptoms than teachers with a normal BMI (18.5–24.9 kg/m2). Other plausible investigations correspondingly confirm that an increase in weight (overweight) is associated with respiratory health problems.65–67 The potential explanation for our finding is that being overweight affects the respiratory system by several mechanisms: direct mechanical changes due to fat deposition on the chest wall, blood vessels, abdomen and upper airway as well as systemic inflammation.68 69 Being overweight causes fat accumulation in the body, which changes respiratory physiology and results in the impairment of various lung function parameters.70 Furthermore, excess weight gain may increase airway resistance and reduce respiratory muscle endurance, resulting in dyspnoea, chest pain and hypoxia.71 72
Also, teachers who were exposed to secondhand smoke at home had a 10-fold higher risk of developing chronic respiratory symptoms than teachers who were not exposed to secondhand smoke at home. This finding is in line with other research reports.73 74 Scientific evidence has firmly established that secondhand smoke contains thousands of chemicals, 250 of which are extremely hazardous to human health and more than 70 of which cause cancer.75 There is no safe level of exposure to secondhand tobacco smoke; even a trace amount can cause serious diseases in the global population.76 Consequently, secondhand tobacco smoke is a significant contributor to indoor air pollution, including in the home.77 Secondhand smokers inhale other people’s smoked breath, which contains unfiltered toxins. Therefore, it has more harmful toxins than mainstream smoke that someone breathes out.78 An investigation from Boston, USA, found that secondhand smoke exposure can cause the narrowing of blood vessels, restricting the flow of blood and reducing lung function.79 Prior studies have also suggested that secondhand smoke in an exposed group leads to reduced lung function and an increased risk of chronic respiratory symptoms such as breathlessness, chest pain, wheezing and coughing.73 80 81
Chalk is a traditional and still widely used teaching aid in most developing countries.82 83 According to the findings of this study, the use of chalk while teaching has a significant impact on the occurrence of chronic respiratory symptoms. Teachers who taught with chalk had twice the risk of developing chronic respiratory symptoms than those who used markers. Similar results were reported in other studies.19 23 59 One possible rationale for this report is that chalk dust contains various chemical impurities that have adverse health effects; when inhaled, these chemicals could aggravate chronic respiratory disease.17 The plausible investigation also confirmed that teachers who work with chalk are at high risk of developing occupational-related lung dysfunction because chalk is a major source of particulate matter in the classroom and chalk dust can cause lacrimation and respiratory health problems.23
Furthermore, in this study, opening classroom windows had a significant effect on the occurrence of chronic respiratory symptoms. Teachers who did not open windows during class had a 2.15 times higher risk of chronic respiratory symptoms than those who did. This finding is in concurrence with previous research reports.51 Our findings could be explained by the fact that not opening classroom windows results in poor indoor ventilation. Reduced ventilation rates can result in poor IAQ in schools as a result of mould, allergens and moisture build-up, which can cause chronic respiratory symptoms.51 84 Besides, dense school occupancy combined with lower ventilation rates may result in an increased incidence of chronic respiratory symptoms, odour and comfort complaints, all of which have significant contributions to student absenteeism and impair learning and teaching performance.26
Although teachers face a high risk of occupational problems, previous research has primarily focused on assessing work-related psychological problems,85 86 and the musculoskeletal and ergonomic needs of teachers,87 88 but there is little or no local data on the country on the respiratory needs of school teachers. The results of this study, therefore, highlight the requirement for governmental bodies to develop a national policy, strategy, and framework for respiratory disease prevention and control programmes for school teachers. Additionally, it helps non-governmental organisations by providing them with baseline data for resource allocation to reduce these under-reported health conditions among teachers. However, some limitations relating to the assessment method employed could not be ruled out. First, we didn’t conduct lung function tests and classroom air sampling for pollutants due to concerns about the feasibility of the large sample size used in the study; instead, we looked at potential risk factors that could lead to respiratory problems. Second, the data obtained for the evaluation of the prevalence of respiratory symptoms were based on participants’ self-reports. Therefore, potential recall bias and under-reporting might be anticipated. Third, due to the nature of the cross-sectional study design, establishing a causal link between the outcome of interest (respiratory symptoms) and the factors that influence their occurrence was impossible. We suggested that future studies use a strong study design, such as prospective or longitudinal case-control, to validate the factors that determine the occurrence of respiratory symptoms. Future studies are also recommended to perform lung function tests and workplace exposure measurements (air sampling) to better understand the determinants of respiratory symptoms.
This study concluded that the overall prevalence of chronic respiratory symptoms was high among school teachers. The occurrence of chronic respiratory symptoms was associated with or modifiable by secondhand cigarette smoking, the use of chalk and failure to open windows during class. In addition, the current study disclosed that those whose families had a history of respiratory problems and overweight individuals were at greater risk of developing chronic respiratory symptoms. Making a smoking-free zone, avoiding smoking in public places, improving ventilation conditions in classrooms by natural methods (opening doors and windows) or using mechanical ventilation systems, controlling the chalk dust, and restricting calories in the food are all necessary actions to take to reduce chronic respiratory symptoms in teachers.
Data availability statement
Data are available upon reasonable request. All the data generated in this study are included in this manuscript. The data sets used and analysed to produce the current manuscript can be obtained from the corresponding author upon reasonable request via email address: firstname.lastname@example.org.
Patient consent for publication
This study involves human participants and was approved by the Institutional Review Board of the University of Gondar, Institute of Public Health, Department of Environmental and Occupational Health and Safety (reference number EOHS/234/2019). Participants gave informed consent to participate in the study before taking part.
The authors thank the Department of Environmental and Occupational Health and Safety, Institute of Public Health, College of Medicine and Health Sciences, University of Gondar for providing ethical clearance. The authors also thank all the data collectors, the supervisor and the study participants.
Contributors AHT initiated the research concept, wrote up the research proposal, analysed the data, presented the results and discussions, wrote up the draft manuscript, reviewed and finalised the manuscript document, the guarantor, and is the corresponding author. MG was involved in data analysis, participated in the presentation and interpretation of results and discussions, and reviewed the draft manuscript document. FMA was involved in data analysis, participated in the presentation and interpretation of results and discussions, and reviewed the draft manuscript document. AD was involved in data analysis, participated in the presentation and interpretation of results and discussions, and reviewed the draft manuscript document. All the authors read and approved the final manuscript. AHT is the the guarantor.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Provenance and peer review Not commissioned; externally peer reviewed.
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