Cold working environments a Covid-19 risk factor, report finds

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Occupational health teams should consider working at low temperatures as a risk factor for Covid-19 infection, as research has suggested that cold working environments are more conducive to transmission of the virus.

An article published in the Occupational Medicine journal has noted that outbreaks have been reported in meat, seafood and poultry processing facilities in numerous countries globally. This is thought to be because of environmental factors including low temperatures, low air exchange rates, air recirculation, metal surfaces and aerosolisation aggravated by high-volume water use.

Other, human, factors include insufficient distancing between workers, poor compliance with facemask use, presenteeism because of insecure poorly paid employment, voice projection against a background of loud machinery, hyperpnoea because of heavy manual labour, limited or non-existent hygiene measures and overcrowded domestic accommodation for migrant workers.

The article, written by researchers at the St John’s Institute of Dermatology at Guy’s Hospital in London, referenced research that identified Covid-19 diagnoses in 9.1% of 112,616 workers in meat and poultry processing facilities in 14 US states by the end of May 2020. By September 2020 the cumulative incidence of confirmed cases in the general population in those 14 states ranged between 0.4 and 3.0%, it added.

It also cited an investigation at Germany’s largest meat processing plant which indicated that an outbreak originated from a single employee who infected more than 60% of colleagues working within a distance of eight metres. The environmental factors that facilitated transmission of the virus at this distance included constantly recirculated cold air (10°C), humidity, airflow and low fresh air exchange rates.

The article said: “It is a long-held common belief that chilling of the body surface predisposes to upper respiratory tract infections (URTIs); however, studies provide inconsistent results. There is more consistent evidence for a relationship between inhaling cold air and increased incidence of URTIs… Low humidity can impact individual susceptibility to infection and the distance which viral particles might transverse the respiratory tract. Breathing cold air chills the nasal airway which compromises respiratory defence against infection by slowing muco-ciliary clearance and by inhibiting leukocyte phagocytosis [a process involving white blood cells fighting off infection].”

It added that employers and OH teams “should consider work in cold environments to be an independent occupational risk factor for developing Covid-19”.

The researchers recommend that employers with low-temperature working environments should conduct risk assessments and individual health risk appraisals to identify staff who have pre-existing health conditions and who may be predisposed to developing infections.

“In addition to standard control measures to prevent the transmission of communicable diseases in the workplace, that include education, early identification and quarantine, employers should implement additional interventions to protect against the cold. These include frequent warm-up breaks, access to hot drinks and meals, protective clothing and, as a minimum, face masks to protect against transmission and to allow warm air rebreathing,” the report has suggested.

It also noted that the risk of airborne transmission can be reduced by improving ventilation, but this can be challenging when there are operational requirements to maintain indoor temperatures significantly below external temperature.