WORKPLACE EXPOSURE CONTROL OPTIONS
(White paper excerpt from Occupational Health Southern Africa)
With COVID-19, it may not be possible to eliminate the hazard. The most effective exposure control measures are associated with prevention of transmission from infected persons and asymptomatic carriers; thus, the exposure pathways and the hierarchy of controls for COVID-19 are vital, i.e. engineering controls, administrative controls, safe work practices, behaviour risk management (a type of administrative control), and PPE. Thus, measures, at the source, to detect early infected and/or potentially infected persons, are key.
According to the National Institute for Communicable Diseases (NICD) case definition, persons under investigation (PUI) who should be tested for COVID-19 are those presenting with acute respiratory illness or a cough, sore throat, shortness of breath, fever ≥ 38 °C, or a history of fever.32 Initiatives to detect PUIs in workplace settings should be governed by a workplace COVID-19 policy, and should include body temperature screening at points of entry as well as measures to reduce the emission of exhaled droplets, i.e. behavioural practices such as ‘controlled-sneezing’,33 and wearing of face masks.30-32 The latter has been proven to be effective in healthcare settings where infected patients wore masks. However, it is plausible that even home-made cloth face masks will reduce the emission of droplets into the air to a certain extent. Definitely, the larger droplets will be captured, and the swelling of the cotton fibres when moisturised may prevent even smaller droplets escaping.
Regarding the droplet transmission pathway, structural measures such as simple (face) screens and barriers used in some customer-facing roles, including those of taxi/bus drivers and banking staff, might offer some degree of protection from COVID-19, compared to the more open interactive style of work that teachers or general shop staff adopt. More drastic measures would be, for example, the transition to self-scanning of purchased goods, and replacement of traditional door handles with elbow-operating systems or automatic doors. Adequate room ventilation in combination with reduced occupancy of rooms are key factors to reduce the long-range transport of aerosols and shorten the associated transmission pathway, as demonstrated in tuberculosis transmission research.20,37 Furthermore, engineering controls to reduce the emission of dust should be extended as it is hypothesised that concurrent exposure to dust may affect exposure to COVID-19.
Adequate personal hygiene, including handwashing, will require that workers are well instructed and facilitated, and should be paired with cleaning procedures to provide frequent and adequate cleaning of surfaces, especially those that are frequently touched by different persons.38 Personal protective equipment which includes gloves, goggles, face shields, face masks, aprons, overalls, hair and shoe covers, and respiratory protection, will only be effective if workers are adequately trainedto use protective clothing and equipment, which includes instructions on how to correctly on, use/wear and off it.
The effectiveness of the facemask type of respirator, or the socalled disposable filtering facepiece (FFP), is very much determined by the ‘fit’, i.e. the presence or absence of facial leakages, rather than the filtration efficacy.39 In addition, it is quite often forgotten that ‘disposable’ implies replacement and not reuse. It will be interesting to determine whether adherence of viruses to dust particles will result in a Trojan horse effect if the particle size is close to the so-called most-penetrating particle sizes, which are in the range of 40 to 300 nm, depending on the filter material.40 As research indicates, appropriate donning practices very much determine the fit of respirators,41 and inappropriate doffing of respirators and gloves enhances crosscontamination. 15,42 Thus, the use of masks, i.e. non-medical masks for non-healthcare workers and the general public, must be accompanied by mask hygiene, and awareness and education.
COVID-19 is now considered a global pandemic and the virus is spreading at an unprecedented rate. Given the challenges highlighted in this paper, it is crucial that scarce resources be appropriately allocated to prepare and respond effectively in a unified and co-ordinated manner across workplaces, countries and continents. Technical operations and testing must be impeccable and quality-assured, and collaboration and communication needs to be strengthened. The actions needed in the occupational health arena are fundamental and will contribute to the prevention of a social, health and economic tragedy. It is the responsibility of the employer to implement a preparedness plan for containing and controlling potential exposures, as well as to review its business continuity plans, in order to maintain a healthy, safe and sustainable workplace.
Source: Occupational Health South Africa : https://occhealth.co.za/pdf/Vol26No2MarchApril2020.pdf