ORIGINAL Assessment of grain dust management systems among selected animal feed manufacturers

The animal feed industry in Kenya has experienced rapid growth due to the increased demand for animal feed around the major towns. That equally increased the risks of exposure to grain dust among the workers. The level of awareness about the risks and the existing control measures has not been adequately studied and documented in Kenya. The overall objective of the study was to assess the dust management systems among selected animal feed manufacturers in Kiambu County, Kenya. The study adopted a cross-sectional study design. A total of 355 animal feed mill workers were sampled using Yamane’s formula. They assessed the dust management systems using structured questionnaires, interviews, and walk-through surveys. SPSS was used to process and analyze the collected data. The results showed that the majority of the workers had not been trained in the elements of grain dust management. None of the workers was aware of the air sampling measurements or the exposure limits. Only 16.13% of the feed millers controlled the dust using other engineering and administrative controls apart from ventilation. The study concluded that there was a need for improvement in dust management measures among the facilities and the workers. The study recommends improvement in the dust control measures whereby the workers should adhere to the set safety and health guidelines and the management of the animal feed manufacturers should provide continuous training, suitable gear, and development of engineering controls to minimize the exposure to grain dust.

particles in their respective occupational environments during the production processes (Meo and Al-Drees, 2005;Subbarao, Mandhane and Sears, 2009;Mohammadien, Hussein and El-Sokkary, 2013). It is acknowledged that limited research and documentation on the same exist in developing countries, including Kenya, which is attributed to poor record-keeping of occupational diseases and non-existent health surveillance systems (Aiguomudu, 2018).
Feed mill workers are potentially exposed to grain dust that may adversely affect their respiratory health (Musa et al., 2000). Researchers have attributed the increase in the prevalence of respiratory symptoms and lung function impairment in various work environments to exposure to grain dust (Elms et al., 2003;Bulat et al., 2004;Abbasi, Ahsan and Nafees, 2012;Mohammadien, Hussein and El-Sokkary, 2013;Aiguomudu, 2018). These studies have highlighted the significance of grain dust exposure in the animal feed industry. The exposure and the subsequent health disorders have contributed to decreased productivity in feed mill workers. Some of the predisposed workers suffer from exacerbated respiratory health disorders, which cost the individual in medical expenses and, more broadly, the organizations in hospital bills, insurance, compensation claims, and lost work hours.
Kenya has experienced steady growth in the animal feed industry. The national production is projected to be between 0.76 and 1.02 million metric tonnes in 2020 (Auma et al., 2018). This is linked to the increased demand for animal feed around major towns, leading to an increase in unregulated animal feed mills (Lukuyu et al., 2011;Omanga et al., 2014). Kiambu county borders major urban centres where demand for animal products, including milk, meat, and eggs, is very high. This implies that animal production is extremely intensive, which has subsequently attracted many unregulated feed mills to set up production units in the country. This has resulted in increased risks of occupational and health-related impacts arising from poor implementation of regulations such as The Occupational Safety and Health Act, 2007 and The Factories and Other Places of Work Act (Hazardous Substances) Rules, 2007, lack of awareness and low personal protective equipment usage among workers (Omanga et al., 2014). Private ownership of most animal feed mills, where a large proportion of them are small-scale, has resulted in the industry focusing more on business continuity and less on regulatory obligations such as health and safety standards in the workplace (Kenya Markets Trust, 2016). This exposes the workers to grain dust, whose consequence is the eventual development of occupation-related illness. This is higher in small-scale mills in developing countries due to poor enforcement of occupational health and safety standards, use of older technology, poor working environment, lack of awareness of potential health hazards, and lack of use of personal protective equipment (Iyogun, Lateef, and Ana, 2019). The first step in the adoption and enforcement of the occupational health and safety standards would be the assessment of the workplace environment and workers' awareness to evaluate the effectiveness and efficiency of the grain dust management systems in preventing and controlling grain dust exposure to animal feed workers. Consequently, it should be noted that most occupational exposures can be reduced or eliminated through engineering controls and the use of personal protective equipment, which are absent in most animal feed mills in developing countries (Aiguomudu, 2018). This study is aimed at assessing the current grain URL: https://ojs.jkuat.ac.ke/index.php/JAGST ISSN 1561-7645 (online) doi: 10.4314/jagst.v21i4.5 dust management systems among selected animal feed manufacturers in Kiambu County, Kenya.

Materials and methods 2.1 Study design
This study adopted a cross-sectional research design as a starting point with a recommendation for a longitudinal study.

Study population size and area
Kiambu County covers an estimated area of 2,543.5 km 2 within the central Kenya region, with most animal feed manufacturers located in Thika's industrial zone as per figure 1. It had 3,136 workers from 35 registered feed milling manufacturers duly recognized by the Association of Kenya Feed Manufacturers (AKEFEMA).

Fig. 1: Map of the study area
A total of 355 respondents formed the sample size from which inferences from the population were drawn. The number was based on Yamane's formula, where n was the sample size, N was size of population, and E being set 0.05 implying a 95% confidence level. target respondents. The questionnaires were based on both open-ended and closed-ended questions, which addressed specific research questions for this study. The questionnaire used in this study was divided into two sections. The first section captured socio-demographic information about the population, such as gender, age, designation, and work experience. The second section gathered information on the practices and respiratory health of the workers. The participants were requested to respond based on their knowledge of existing rules and regulations regarding occupational safety and health; the existence of safety and health systems within the workplace; and their respiratory health assessment. The questionnaires offered anonymity, thus encouraging the respondents to answer. A walk-through survey was conducted through the business unit to record the existing working conditions and to corroborate the findings on the workers' safety and health practices. This was done using an observation checklist that took into account direct observations of the safety risks, safety controls, and use of personal protective equipment. Further, interviews were used to obtain data from the senior management about the company's profile to support the survey findings.

Data Analysis and Presentation
Before the analysis, all questionnaires were checked for incompleteness, duplication, and inconsistencies. Firstly, the data collected was edited and coded to get the relevant data for the study. Quantitative data collected from questionnaires and observation checklists were analysed using descriptive statistics using SPSS (Statistical Package for Social Sciences) and presented as percentages and frequencies. The study's statistical significance level was at p<0.05 or a 95% confidence level.

Response rate
A total of 292 questionnaires were duly filled out by the respondents from the 355 questionnaires administered by the interviewers. This was an 82.25% response rate. Mugenda and Mugenda (1999) state that a response rate of 50% is adequate for statistical reporting.
URL: https://ojs.jkuat.ac.ke/index.php/JAGST ISSN 1561-7645 (online) doi: 10.4314/jagst.v21i4.5 Table 1 presents the results of the socio-demographic data of the respondents There were more males in the study than females, comprising 88.36%. The respondents within the age group 18-29 were the highest in number, followed by the age group 30-39, and 10.5% were comprised of age groups 40-49 and 50-59, with a mean age of 30.54 years. Approximately half of the respondents had completed secondary school education (47.95%), while nearly a fifth had primary school education (19.52%), and more than a third had tertiary education (32.53%). More than half of the respondents (54.45%) had between one and five years of URL: https://ojs.jkuat.ac.ke/index.php/JAGST ISSN 1561-7645 (online) doi: 10.4314/jagst.v21i4.5 experience, while those with six years or more of work experience accounted for 28.08%. Twothirds of the respondents were machine operators or attendants classified as operational-level employees (66.78%). The middle-level employees comprised a fifth of the respondents, including the administration (20.21%) and the engineers (1.37%). The management, who were managers or supervisors, consisted of 11.64% of the respondents. A few respondents (7.88%) were current smokers. Table 2 shows the results of the reported dust management control measures at the animal feed companies in Kiambu County.  70.97% of the animal feed production facilities had some form of general and local exhaust ventilation, with no visible mould on the raw materials and finished products in the 31 millers. Despite this, there was no animal feed millers' workspace that was free from dust. In furtherance, none of them had warning signage and Material Safety Data Sheets (MSDS) for the inputs and products. Only 16.13% of the feed millers controlled the dust using other engineering and administrative controls such as segregation of the work processes, structural dust control systems such as dust collectors, and routine cleaning procedures. Workers in all mills tipped the bags into the feeding inlet while facing away and shook the bags when emptying them, stirring dust in the surrounding air. During the cleaning process, dust was URL: https://ojs.jkuat.ac.ke/index.php/JAGST ISSN 1561-7645 (online) doi: 10.4314/jagst.v21i4.5 generated in all the milers. More than half of the workplaces had obstructive objects near the air inlets and outlets within the workplace. It was observed that no worker wore the dust protective gear properly.

Discussion
There were more males in the study than females, which is attributable to the high level of physical labor involved. It can be deduced that this sector is male-dominated. This study finding is consistent with the results of Straumfors et al. (2016) on the cross-shift respiratory response to bioaerosol exposure of grain dust, where the male respondents were 94% while the female respondents were 6%.
There were high literacy levels among the respondents, which could be used as an opportunity by the management of the animal feed facilities to provide continuous training to improve their workers' knowledge of the dust control measures. This study finding is not consistent with the findings by Tosho et al. (2015) on the prevalence of respiratory symptoms and lung function of the flour mill workers in Ilorin, Nigeria, which showed that 26.7% of the workers had no formal education, 0.9% attended primary school, 11.9% went to secondary school, and 36.6% had tertiary education. The disparity is a result of the study focusing on flour mill workers and the differing adult literacy rates between Kenya (78%) and Nigeria (59.6%) (UNESCO, 2013).
The majority of the respondents had between one and five years of experience, implying that there was a high personnel turnover ratio that would amplify the healthy worker effect and reduce the animal feed facilities' capacity to retain workers with good knowledge of and practices for the dust control measures. This study finding varies with the results of the studies in Nigeria by Iyogun et al. (2019) and Tosho et al. (2015), attributable to the differing labour markets in Kenya and Nigeria. Iyogun et al. (2019) reported that about 75% of the grain miller workers had worked for more than 5 years, whereas Tosho et al. (2015) found that 55.4% of the flour mill workers had worked for more than 5 years.
The majority of the workers were neither trained nor aware of the various elements of dust management procedures, which increases the risk of occupational diseases or other effects related to grain dust exposure. Continuous training is needed in promoting a safety culture within the workplace. These study findings were supported by a study conducted in bakeries located in the United Kingdom where 40% of the fifty-five bakeries conducted some form of training on flour dust to employees during their job orientation, and 27% of the bakeries were aware of the occupational exposure limits (Elms et al., 2005).
Very few workers reported having been provided with PPE by their companies, and where the PPE was available or self-provided, there was no worker who wore the dust protective gear properly. The importance of PPE is very vital since it is the last resort when minimizing the exposure to grain dust. This was consistent with the study conducted by Adeoye et al. (2015) to evaluate the awareness of occupational hazards among sawmill workers in Osun State, URL: https://ojs.jkuat.ac.ke/index.php/JAGST ISSN 1561-7645 (online) doi: 10.4314/jagst.v21i4.5 Nigeria. The study findings were that employers rarely provided them, and when they did, they were not long-lasting. The study findings on low and improper usage of PPE were similar to a study conducted by Kayode (2010) that sought to assess the awareness of work-related hazards and safety measures. This was done in Ilorin, Nigeria, involving 257 workers from eleven sawmill factories where less than 20% of the workers wore protective gear. Similar findings were observed by Adeoye et al. (2015), whose study was to evaluate the awareness of occupational hazards among sawmill workers in Osun State, Nigeria. It was observed that the reported usage frequency of personal protective equipment was nil except for facemasks, gloves, and goggles, whereby the percentage of the workers using them frequently was 2%, 5%, and 10%, respectively. This low usage was attributed to non-availability (Adeoye et al., 2015). In addition, low usage may be attributed to the health belief model, where workers might only take action when they perceive a hazard to cause harm or injury to them (Rosenstock, 1974 Only 16.13% of the feed millers controlled the dust using other engineering and administrative controls such as segregation of the work processes, structural dust control systems such as dust collectors, and routine cleaning procedures. This is because the initial cost of setting up the engineering controls is higher as compared to the administrative controls. This causes the management of the animal feed facilities to be reluctant about installing them and focus on profit maximization. These study findings were similar to those observed in the study conducted to assess the control measures among bakery workers in Edo Central Senatorial District, Nigeria, where structural controls and local exhaust ventilation were scarcely available (Aiguomudu, 2018).

Conclusion
The majority of the workers had not been trained in dust management techniques such as dust management procedures, grain dust hazards, and the use of PPE. The majority of the workers reported having not been provided with PPE by the companies. Though the majority of the workers self-provided their PPE, it was observed that no worker wore the dust protective gear properly.
The majority of the animal feed production facilities had some form of general and local exhaust ventilation, although there was no animal feed millers' workspace that was free from dust. Only 16.13% of the feed millers controlled the dust using other engineering and administrative controls such as segregation of the work processes, structural dust control systems such as dust collectors, and routine cleaning procedures. Thus, there was a need for improvement in dust management measures among the facilities and the workers.

Recommendation
Workers should be provided with ongoing training and appropriate protective equipment by animal feed mill companies. Additionally, they should improve the existing control measures for grain dust and develop appropriate control measures where none exist. On the other hand, the workers should adhere to the set safety and health guidelines and wear the appropriate personal protective equipment at all times. This will promote awareness of the grain dust hazards and help stimulate a safety and health culture. This is per the Occupational Safety and Health Act, 2007 and The Factories and Other Places of Work Act (Hazardous Substances) Rules, 2007.

General acknowledgement
The researcher ensured that the potential respondents were not coerced into taking part in this study. The principle of voluntary participation was followed by ensuring informed consent was obtained from the feed mill workers and managers. The researcher guaranteed the participants' confidentiality by assuring them that the information provided was used only for academic purposes.

Declaration of interest
This article has been approved by the ethics committee at Jomo Kenyatta University of Agriculture and Technology (JKU/2/4/896B) and a research license from the National Commission for Science, Technology, and Innovation (NACOSTI) granted by the Kenyan authorities.