The present study was a cross-sectional study which was carried out at four main hospitals in Ibb city, Yemen namely: Al-Manar, Al-Noor, Al-Thawrah and Naser Hospitals from November 2019 to May 2020. Taiz University in Yemen granted ethical approval for the study (TU/2021-2001). Prior performing fieldwork, hospital management gave their written consent. Before answering the questionnaires, each participant gave their verbal consent. Each set of questionnaire consists of the title of the study, a full explanation about the study objective, expected outcomes, the nature of voluntary participation, and the maintenance of confidentiality and privacy.

Inclusion criteria: All participants, in all departments of the main hospitals, who were in direct and indirect contact with medical wastes and those who accepted to participate.

Exclusion criteria: All HCWs who were on temporary contract, those working for less than one week at given period in the unit, participants who were in the night shift were excluded. Participants who were unwilling to participate in the study and those who wished to discontinue their participation were allowed to do so without any restriction.

Sample size calculation: The following equation was used to calculate the sample size:

Where; n: Sample size, N: Population size, z: Confidence level, d: Error proportion, p: Probability.

Population size: 617, Confidence level: 1.96, Error proportion: 0.05, p: Probability: 0.5.

The study population included all HCWs in the four main hospitals including physician, nurses, laboratory technician, and others (physiotherapists, nutritionists, pharmacists, dentist and radiographer.

Simple random sampling was used to select the study participants. HCWs in all departments were invited to participate in the study. A permission was sought from the hospital administration prior to carrying out questionnaire distribution. All participants were given questionnaire to be completed, after obtaining verbal consent from them. A total of 337 questionnaires were distributed and 335 questionnaires were returned as follows: Naser-103 participants, Al-Thawrah-112 participants, Al-Noor-60 participants and Al-Manar Hospitals-60 participants.

This study utilised a self-administered questionnaire to gather data from the respondents. Confidentiality was maintained by avoiding use of names. The survey tool had three sections. Section one had socio-demographic information such as age, gender, occupation, department, and years of experience. Section two was about medical waste management knowledge, such as medical waste risks, training, guidelines in the departments on how to handle medical waste, medical waste separation, waste handling safety, and the availability of facilities to ensure the safe disposal of medical waste. Section three focused on medical waste management practices such as reading medical waste disposal guidance and leaflets, enforcing laws related to medical waste, wearing Personal Protective Equipment (PPE), treating needles and sharp instruments with caution, washing hands and raising awareness in others about the risk of medical waste.

It was assessed using the WHO disposal of medical waste knowledge questionnaire for HCWs [2]. Some modifications (wordings were changed) were made to suit the respondents local language and culture.

The tool included three responses - yes, no and don’t know. Correct responses were counted and recorded for each respondent as the positive response gets the high scores. Higher scores indicate a positive practice and better knowledge of disposal of medical waste among HCWs.

The questionnaire was in Arabic language and it took about 15 minutes to be filled. Face validity was determined through pilot study with the help of the questionnaire on 30 HCWs. The reliability was assessed using Cronbach’s alpha. The Cronbach’s e alpha value of the questionnaire was 0.856.

Data analysis was performed using SPSS version 25.0. Frequency count, percentage, standard deviation and mean values were used to analyse the knowledge and practice of disposal of medical waste. Tests that were used to analyse data were Mann-Whitney test, Pearson’s Chi-square test, and Spearman test. Significance was set at <0.05 level.

A total of 337 questionnaires were distributed and 335 returned, giving a response rate of 99%. The age of participants ranged from 20 to 56 years with mean age of 31.36±8.121years. The mean age of female participants was 28.51±6.327 years and that of male participants was 33.08±8.599 years. Most of the participants had a diploma (47.8%), their occupation was nursing (41.2%), laboratory technician (20.3%), physician (19.4%), midwives (5.1%) and they had less than five years or work experience (50.7%) [Table/Fig-1].

About 68.4% of the participants mentioned that there are laws on how to deal with medical waste in their hospitals. Around 18.3% of study did not distinguish hazardous and non-hazardous medical waste. About 29.8% of the study participants joined immunisation campaigns to prevent any possible future infection of medical waste [Table/Fig-2].

About 58.9% of the participants mentioned that they accepted the offer to attend training on medical waste management [Table/Fig-2]. This study found that only 53.3% of HCWs always wore protective clothes when dealing with medical waste. Furthermore, 85.9% of the study participants deal carefully with needles and sharp tools after use. In addition, 76.7% of the participants always wash hands at the end of their work with a disinfectant or sterilise [Table/Fig-3].

The mean knowledge of the participants was good (1.39±0.45), as most of the answers in the knowledge domain were high. This indicates that HCWs have good knowledge on medical waste disposal. In the practice domain, most of the answers were also positive and the overall mean practice was (3.41±0.45). This indicates that HCWs have good practice on medical waste disposal. Mann-Whitney and Kruskal Wallis tests were applied to compare scores of each domain with socio-demographic factors. For knowledge, participants with diploma qualification showed significant higher mean knowledge score than others (p=0.030). Nurse showed statistically significant higher mean knowledge and practice scores than others (p=0.001, p=0.002; respectively).

Participants from Naser hospital has a higher mean knowledge score than participants from other hospitals (p=0.001). No statistically significant difference in scores was observed among other socio-demographic factors [Table/Fig-4].

A moderate positive correlation was found between knowledge and practice (r=0.505 and p=0.001). There was a statistically significant association between different hospitals and knowledge (p=0.013). Participants from Naser hospital had higher mean scores (26.3%) compared to others. There was a significant association between occupation and knowledge (p=0.014). Nurses scored the highest mean (33.7%) compared to other HCWs. Age and years of experience did not significantly influence the knowledge and practice of the HCWs [Table/Fig-5].

Healthcare activities restore health and save lives, however, it generates many hazardous medical wastes that affects human health. Disposal of medical wastes have become a global emerging issue. Therefore, the objective of this study was to determine knowledge and practice of HCWs at the main hospitals in Ibb city, Yemen.

The findings of this study reported that more number of nurses participated in the study. This study was similar to a previous one conducted in South Africa, in which more nurses than physicians participated in such studies [8]. This demonstrated that nurses are still eager to volunteer in such studies.

This study indicates that respondents had a good knowledge. The present study contradicted another study from Yemen, where knowledge on medical waste among HCWs in private and public hospitals was insufficient (44%) [7]. A study from India found that the medical practitioners did not have sufficient knowledge about how to properly dispose of medical waste [9]. This may due to the differences in the studies location, participants and design.

Furthermore, in this study, 68.4% of the participants mentioned that there are laws on how to deal with medical waste in their hospitals. In developed countries, where definite rules and regulations exist at all levels of the healthcare system, it is vital to plan standard operating procedures for medical waste management in hospitals. Furthermore, proper monitoring and enforcement strategy are crucial for proper medical waste management [10]. Yemen is yet to adopt a practical guide in managing and disposing medical waste. The current practice is co-disposal with non-hazardous wastes at landfill sites [11]. In Yemen, the most popular method of disposing of medical waste is to bury them in open dumps [11]. These practices are also carried out in some Arabic nations like Egypt [12]. Microwave plasma sterilization and incineration is the method used for disposal of medical waste in United States of America (USA) [13]. Total 3% of the study participants never separated medical waste. A study from Iran reported that hazardous waste was mixed with non-hazardous waste generated in the hospitals, then transferred to the final disposal site [14]. Another study reported that 67% of the HCWs did not segregate waste at source [15]. Several studies reported poor medical waste segregation practice among HCWs [16,17]. An Indian study showed that sometimes wastes were mixed with non-hazardous byproducts, making the whole operation ineffective [18]. Therefore, there is an urgent need for medical waste separation and training about medical waste management for all HCWs in Yemen. According to the general standard roles, healthcare waste is expected to be in coloured containers. These issues may be due to the lack of awareness and insufficiency funds. Only 38.1% of the participants reported that incidents of mal-handling medical waste were reported. The reported incidence of sharps injuries in literature ranges widely among HCWs per year; therefore, the underestimation of accidents could be a widespread concern [7,11]. The under reporting may be due to time constraints and fear of punishment from their superior.

About 29.8% of the study participants are aware of immunisation campaigns to prevent any possible future infection of medical waste. This percentage is discouraging and more immunisation campaigns should be held in the whole country to promote immunisation and also to encourage more HCWs to be vaccinated against Hepatits B Virus (HBV) and other vaccinations. Furthermore, 85.9% of the study participants always dealt carefully with needles and sharp tools after use. In addition, 76.7% of the participants always washed hands at the end of the work. The high percentage of washing hand and handling needles and sharp tools carefully indicated the high knowledge among the participants. However, more training and education need to be provided at all healthcare facilities nationwide to increase awareness about the risk of medical waste. No previous study conducted in Yemen investigated the immunisation among HCWs. In Yemen there is no regulation regarding immunising the HCWs before starting the clinical practice like taking HBV vaccination. Therefore, there is an urgent need to vaccinate the healthcare workers using HBV vaccine and COVID-19 vaccine.

PPE such as face masks, gloves, goggles, gowns, and aprons are necessary for individual protection from exposure to pathogens like COVID-19 and contaminants like medical waste. This study reported that only 53.3% of HCWs wear protective clothes when dealing with medical waste. A previous study from Yemen, PPE was used by 20% of HCWs in public hospitals and 33.3% of HCWs in private hospitals [7]. An Egyptian study found that more than 70% of nurses wear PPE [19].

This may be attributed to the general situation in Yemen, which is facing the worst humanitarian crisis in the recent history. In addition, to the war and conflict that has been ongoing since 2011. Total 58.9% of the participants said if a course is offered about medical waste management they would join.

A lack of medical waste management training among HCWs staff has been identified in several studies in India, Pakistan and Bangladesh [20-23]. A similar finding from Ethiopia reported that 53.1% of HCWs didn’t take any training on medical waste management [24].

Gender: In this study, gender was not found to be associated with knowledge and practices. A study from India also showed that there was no statistical relationship between knowledge and gender [25].

Age: The result of this study showed that there was no significant association between age and knowledge. Previous research backs up present study findings that there was no significant association between age and knowledge [26,27]. However, one study found a substantial link between age and knowledge [28]. The differences in these studies may due to the study design, type of population and sample size.

Occupation: This study found that nurses are more knowledgeable about medical waste management than others (p=0.001). This was similar to previous studies indicated that nurses had better knowledge than other healthcare workers [29-35]. This was in contrast with the study that found no significant association between professional category and practice [25]. Another study done in Ethiopia showed medical doctors had better risk perception than other health workers [24]. This may be explained by the fact that the nursing staff gain experience by working on a regular basis and handling medical waste regardless of their qualifications, years of experience, or place of employment.

Education and knowledge: In this study, knowledge of HCWs regarding medical waste management was statistically significant in relation to their education. However, practice of HCWs was not statistically significant in relation to their education. On the contrary, a study from Iran showed that the practice of health-care regarding medical waste management was statistically significant in relation to the level of education [35]. As a result, education plays an important role in raising awareness among healthcare workers.

Type of hospital: Type of hospital showed a statistically significant related to knowledge (p=0.001) but not significant for practice (p=0.124). The results show that participants from Naser hospital had a higher level of knowledge than others hospitals. This may due to the presence of the international organisation called Doctors without borders or Medicines Sans Frontiers (MSF) in this hospital.

Years of experiences: The results of this study showed that years of experience did not have association with knowledge of medical waste management. This was in contrast with previous studies [19,25,36]. These differences may due to the differences settings and priorities in healthcare systems.

Correlation: The results of the study found a moderate positive relationship between knowledge and practice of medical waste of medical waste disposal at selected hospitals in Ibb city, Yemen. Several previous studies found a correlation between participants’ level of knowledge and their practices [37-39]. In addition, another study showed that increase in the knowledge will increase the good practices [40]. Moderate correlations recorded in this study can be attributed to the fairly consistent high score levels of knowledge and practices of the respondents.

This study was conducted only in one Yemen city and thus it may not represent the entire country. In addition, the study was conducted during Yemen’s conflict and the war, during which half of the country’s healthcare facilities were destroyed, local specialists and experts fled the country and everyone’s main concern was to survive.

Occupation, type of hospital and education level significantly influenced the knowledge of Yemeni nurses. Contentious education should be focused on medical waste management among healthcare workers nationally. There is an immediate need for ongoing training about medical waste management for hospital staff at Ibb and other states in Yemen. Training should be carried out by the Ministry of Health, Yemen and universities in different forms such as seminars, workshops, and conferences. Its important to organise medical campaign in order to build awareness and urgency of safe disposal of medical waste and medical waste management among general population.