Ventilation

COVID–19 is a health and safety risk. Employers have obligations to ensure the health and safety of workers and others. They must have a plan on what will be done to protect and support workers, and health and safety representatives (HSRs) must be consulted on this plan.

COVID is caused by the virus SARS-CoV-2. The virus spreads through the air from infected people, so it is essential that every effort is made to remove and reduce any contamination of the air we breathe.

When we breathe or speak, we generate tiny aerosols that cannot be seen by the naked eye.

Indoors, if the ventilation is poor, these aerosols accumulate and linger in the air over time – just like cigarette smoke, but invisible. People with new infections are most contagious just before they get sick, even when they don’t even cough.

A cough, sneeze, shouting or singing generates significant aerosols. Speaking and breathing are constant, so over time these may result in more aerosols lingering in the air than a single cough.

The longer we are indoors, the greater the risk of inhaling enough virus, if it is present, to be infected. Even vaccinated people have been infected indoors, especially with the Delta variant.

Both the World Health Organization and U.S. Centers for Disease Control and Prevention say that poor ventilation increases the risk of transmitting the coronavirus.

The best way to prevent harm

As with any other risk, employers/PCBUs must consider how to implement the most reliable ways to prevent harm. Applying the hierarchy of controls to COVID-19 may require multiple measures to be implemented in a workplace. The WHS Regulations require that ventilation enables workers to carry out work without risks to health and safety [WHS Reg 40.e].

Improve ventilation:

As coronavirus is spread by breathing in contaminated air, clean air inside a building is essential. There are several ways to improve air quality:

  • increase the amount of outside air circulating by opening windows wherever it is possible – this includes in vehicles or mobile plant
  • improve the indoor air quality by ensuring that the air conditioning systems are well maintained and circulating fresh air not recirculating the air
  •  increasing the air exchange rate, which is the measure of the number of times the air inside a building gets replaced with air from outside in an hour. The actual air exchange rate required will depend upon the number of people and size of the area.
  • if it is not possible to do either of the above, the use of portable air cleaners should also be considered. Note – but these must be maintained – e.g. external cleaning with special wipes, but cleaning and maintaining the filters from deep in the machines must be done using precautions.

To help checking whether there is enough fresh air circulating, monitors can be used that check the levels of CO2. The outside air we breathe is about 300-500 ppm of CO2. Indoor C02 levels need to be kept lower than 1000ppm – the recommended levels are between 600- 800ppm.

NOTE: CO2 is only a measure of how much (or little) fresh air is circulating not a measure of whether there is any virus in the air.

Expert assistance is required to ensure that air exchange rates and filtration systems remove contaminants, limit the circulation of contaminated air and keep levels of CO2 down. It is important that fresh ventilation exhaust outlets are:

• not near where people work or walk by

• away from any inlets for the fresh air. Drawing in contaminated air must be avoided.

Health Care settings

For health care settings there are specific ventilation requirements for isolation rooms, including negative pressure rooms. Air filters have been shown to be very useful in hospital settings.

Respiratory Protection

Respiratory protection, like other PPE is the lowest level of control. PPE should be used in addition to addressing ventilation, not instead of it.

Settings where workers are working with known or potential COVID positive people will also need to a have a higher level of respiratory protection than other workers. This will include the use of P2/N95 respirators which provide a very close facial fit and efficient filtration of airborne particles. It is important that workers are fit tested to ensure proper fit and are also fit checked on each occasion to ensure that it is applied correctly.

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