When the first wave of COVID-19 hit Australia in March 2020 the experts believed that transmission via surfaces was the primary method of infection. However, it is now believed that catching COVID-19 through surfaces is rare.

In fact, most people catch COVID-19 through the air, either directly from droplets, or through aerosols. And this almost always happens indoors.

In early July, over 200 scientists from 32 different countries penned a letter to WHO asking them to recognise the significance of aerosol transmission.

What Is Aerosol Transmission?

Aerosol are very tiny droplets (of 5 microns or less in diameter) that you emit when you breathe, speak, and laugh. Because these particles are tiny and light, they can remain suspended in the air and then inhaled by someone else

While scientists don’t know exactly how long micro-droplets can linger in the air, it could be hours.

Can A Buildings’ HVAC Spread COVID-19?

The short answer is YES, it is possible for an HVAC system to spread COVID-19. This can be done in 2 ways:

  1. The airflow from the HVAC can push aerosol droplets containing the virus further than they would have otherwise travelled. There have been several cases of this happening in China.
  2. The aerosol droplets containing COVID-19 can travel through the HVAC system to the cooling coils. The COVID-19 virus can attach itself to bacteria on the cooling coils which then act as a host. The bacteria host will help the virus particle stay active for longer.

This blog post explores the ways in which a virus can spread within a commercial building.

In particular, it outlines the ways in which a company like Clean Air Filtration Services can minimise the chance of virus spread through its HVAC cleaning and Compliance programs.

How Does A Virus Spread Within A Building?

A virus can be spread in a number of ways. Typically, the spread starts with an infected person coughing or sneezing droplets onto a surface, into the air, or onto a person nearby.

Other people can be infected if:

  • The droplets land directly in their eyes, nose or mouth.
  • The person touches a surface on which the droplets have landed and then they transmit the droplets to their mouth.
  • Very small droplet particles stay airborne long enough to travel & infect areas & people outside the original sneeze zone. This is called airborne transmission.

Can An Air Conditioner Spread An Airborne Virus?

The short answer is that it is possible for an air conditioner to spread an airborne virus and contaminate adjacent areas.

The likelhood of this happening is dependent upon:

  1. The potency of the droplet particles.
  2. The length of time the virus stays infectious within the droplet particles.
  3. The length of time the droplet particles stay airborne.

In a recent NETFLIX documentary outlining the spread of SARS they state:

“…a fan blew the virus back up into the building’s ventilation, and into the apartments above. Then the wind was likely blowing the virus to nearby buildings making it much more difficult to contain… In total 329 people were infected in this apartment complex…”

(Netflix, ‘EXPLAINED, The Next Pandemic’, 2019, 13.3 minutes in)

Note that the World Health Organisation has stated in March 2020 that they are not seeing airborne transmission of Coronavirus. This is despite some studies reporting that Coronavirus stays airborne for up to 3 hours.

Can An Air Filter Trap An Airborne Virus?

Most viruses vary in diameter from around 20 nanometers to 400 nanometers.

A HEPA filter is able to filter particles down to 300 nanometers.

In addition, a smaller virus particle will generally not move in a straight line and is therefore likely to make contact with the filter fibres. Once trapped, the virus particle would stay safely on the filter until it becomes inactive. Therefore, although a typical Coronavirus particle is about 100 nanometers it is still likely to be trapped by a HEPA filter.

Other filters that can kill a virus include:

  • Ultraviolet (UV) Based Filter – Several minutes of UV light exposure can break down the virus molecule and render it inactive.
  • Photocatalytic Based Filter – Virus can be broken down by electrostatic and oxidation processes.
  • Catechin Based Filter – Can have antiviral properties.

What Substances Can Be Used To Deactivate The Coronavirus?

The virus molecule has a lipid or fat-like covering. Therefore many cleaning agents are effective because they destroy the virus by attacking this fat layer. Once the lipid layer is destroyed the fragile virus molecule is exposed and quickly becomes inactive.

Some substances used to successfully deactivate the virus molecule include:

  • Soap – Can break down the lipid layer.
  • Bleach – Can break down the lipid layer and the enclosed virus molecule.
  • Peroxide – Can break down the lipid layer and the enclosed virus molecule.
  • Alcohol – Can break down the lipid layer.
  • Heat – Can melt the lipid layer.

Why Is It So Important To Kill HVAC Bacteria & Bio-contaminants During A Pandemic?

Australian Standards AS 3666 Part 2 states that HVAC:

  • Coils – should be inspected monthly and cleaned when necessary
  • Ductwork – should be inspected annually and cleaned when necessary
  • Fans – should be inspected at three monthly intervals and cleaned or repaired as necessary

This is the minimum period between inspections and cleaning.

However, there are two very good reasons why you may need to clean your HVAC system more regularly than this during a pandemic:

1) Secondary Infections Become Deadly

Death rates due to coronavirus are significantly higher in people with a pre-existing condition. Therefore, if a resident of your building were to be infected with legionella due to poor HVAC cleaning practises, they would be open to an even more serious problem if they were to then catch Coronavirus.

2) The Virus Will Be Infectious For Longer

Viruses need a host cell, which can be bacteria, fungi, or an animal, including a human. With help from the host, viruses are then able to multiply. 

If a virus finds a host in the HVAC system it could remain dangerous for a long period of time. It is therefore important to clean your HVAC system more regularly to ensure that it is clear of bacteria, fungi and bio-contaminants.

If you are a commercial kitchen operator (cafe, restaurant or fast food business owner), a building owner or a building manager, you have a duty to keep your kitchen exhaust system safe.

This obligation falls under the Work Health & Safety (WHS) regulations and under the food safety standards for commercial kitchens. In particular, the Australian Standard AS 1851-2012 outlines a series of minimum inspection, maintenance and record-keeping requirements for kitchen exhaust systems.

In the event of a fire, failure to comply with these may be deemed as negligent or failure of duty. It is very possible that your insurance company will classify your fire insurance policy as invalid if you are not compliant.

The repercussions of an invalid fire insurance policy can be catastrophic for both the business owner and the building owner. As a result, both parties should be playing an active role in ensuring compliance.

Manufacturers of kitchen exhaust systems often provide their own inspection and cleaning programs, which may be more stringent or frequent than those in AS 1851.

Alternatively, commercial kitchen cleaning companies like Clean Air Filtration Services have well-drilled processes and systems that take into account AS 1851-2012 standards, manufacturers cleaning recommendations, as well as the unique usage of the cooking facilities which the exhaust system serves.

For example, if you are a popular restaurant with a busy kitchen that handles fatty or greasy product, you could need more attention than a restaurant that is less busy.

Filter Cleaning vs Canopy & Exhaust Cleaning

Grease Filters require more regular attention than kitchen canopies and kitchen exhaust systems. For example, Clean Air Filtration Services have clients that use our filter exchange service:

  • Once every 4 weeks
  • Once a week
  • Twice a week

The frequency is totally dependant on the activities within your kitchen. A heavy use kitchen is considered to be 12-16 hours per day. A moderate use kitchen is considered to be 6-12 hours per day. While a light use kitchen is considered to be 2-6 hours per day. Of course, the food you are cooking is also very relevant.

Alternatively, a canopy and exhaust clean can vary from:

  • Once every 12 months (as outlined in AS 1851-2012 as the minimum)
  • Once every 6 months

The recent kitchen fire in a Hungary Jacks restaurant highlights the need for commercial restaurants to implement regular and professional canopy and exhaust cleaning procedures.

On June 24, it is reported that a fire started in a deep fryer in the Traralgon restaurant before quickly spreading to the kitchen canopy, and then onto the kitchen exhaust system and into the ceiling.

The fire was extinguished by CFA crews, but not before inflicting significant damage to the ceiling and kitchen. Around 20 people were evacuated with at least one person treated for minor smoke inhalation.

Commercial kitchens are constantly depositing layers of grease on surfaces surrounding cooking surfaces. These surfaces include kitchen fryers, hot plates and kitchen canopies.

In addition, the kitchen exhaust system is constantly sucking grease-filled air through the air filters and into the exhaust ducts. If left unmanaged, the result is a very dangerous greasy fuse that sits ready to explode into flames.

Most restaurant owners and managers understand that it is their responsibility to regularly clean their kitchen canopy and kitchen exhaust system. They’re aware that there is an Australian standard that outlines the requirement for an annual clean.

However, many commercial kitchens don’t realise that an annual clean is a minimum and that bigger kitchens require professional cleaning more regularly.

Further, the industry has seen the emergence of a group of unprofessional cleaning companies that are great at marking, but very poor at cleaning exhaust systems. This new breed of cleaning companies simply clean the kitchen canopy and filters but leave the exhaust ducts and other important areas.

Commercial kitchen owners and managers have been warned. Your livelihood is at risk as too is the safety of your patrons. Make sure you are using a professional and experience commercial kitchen cleaning company like Clean Air Filtration.

We have been servicing the restaurants and cafe’s of Melbourne for nearly 30 years. We’ll manage the cleaning of your Kitchen canopies and exhaust systems as well as implement our world-leading grease filter exchange service. Call us on 03 9303 9661 to learn how we can help.

Let’s start from the beginning. What is ventilation and why do we need it?

Ventilation is the provision of air from a clean outdoor air supply, to an indoor building.

A building requires clean air to:

  • provide oxygen for inhabitants to breathe,
  • dilute or remove air contaminants,
  • reduces odours,
  • provide thermal comfort,
  • provide smoke control or smoke clearance.

Humans breathe in oxygen and breathe out carbon dioxide. Left un-moderated, this could be dangerous in a building with not enough oxygen in the building to service the inhabitants.

Ventilation can be either natural or mechanical or a combination of the two.

Natural ventilation can be achieved through openings in the external facade of a building. Windows, doors, vents and grilles are examples of this. However, in some buildings, natural ventilation systems are complex and controllable engineered systems.

Mechanical ventilation essentially uses fans to move air between the inside and outside of a building.

Indoor Air and Indoor Air Contamination

Indoor air can suffer from a range of contaminants from many different sources including

  • organic substances such as microorganisms and microbial debris,
  • pollens,
  • animal hairs,
  • metals,
  • fibres,
  • fine particles,
  • and gases.

Microorganisms can include:

  • Legionella pneumophilia
  • Mycobacterium tuberculosis
  • Moulds and mould metabolites
  • Viruses

it’s critical that HVAC systems and air-handling systems are maintained in order to control microorganisms accumulating in building air systems.

The standard explicitly mentions the following 5 parts of an HVAC system that must be part of a maintenance program:

  1. OUTDOOR AIR INTAKES & EXHAUSTS – Inspect, clean or replace where necessary.
  2. AIR FILTERS – Inspect, clean or replace where necessary.
  3. HUMIDIFIERS – Inspect, clean or replace where necessary.
  4. EVAPORATIVE AIR-COOLING EQUIPMENT – Inspect, clean or replace where necessary.
  5. DUCTS & COMPONENTS – Inspect, clean or replace where necessary.

The responsibilities of a facility manager relating to the ongoing maintenance of a buildings’ HVAC system are clearly outlined in the applicable Australian standard – AS/NZ 3666.2:2011.

The title of this standard is “Air-handling and water systems of buildings – Microbial control Part 2: Operation & maintenance“. As the title indicates, it’s critical that HVAC systems and air-handling systems are maintained in order to control microorganisms accumulating in building air systems.

The standard explicitly mentions the following 5 parts of an HVAC system that must be part of a maintenance program:


Frequency  – Monthly

Inspect, clean or replace where necessary.


Frequency  – Monthly

Inspect, clean or replace where necessary.


Frequency  – Monthly

Inspect, clean or replace where necessary.


Frequency  – At least every 3 Months

Inspect, clean or replace where necessary.


Frequency  – Depending on component between 1 Month & 12 months

Inspect, clean or replace where necessary.

Components include:

  • Coils
  • Trays & Sumps
  • Condensate drains, tundishes & traps
  • Ductwork
  • Fans
  • Terminal Units
  • Supply air outlets
  • Return air & relief air grilles

The standard also outlines the need for the existence of Maintenance Manuals and Maintenance Records.

The Maintenance Manual should include details of the maintenance management program including plant servicing, cleaning schedules, and replacement periods for equipment items and components.

Maintenance Records should include:

  1. Date and nature of service performed.
  2. Results of periodic testing.
  3. Details of defects found and remedial procedure undertaken.
  4. The name of the person and company performing the service.

Maintenance manuals and Maintenance Service Records shall be readily available at the site for inspection by regulatory authority upon request.

For the purpose of maintenance management, the maintenance service records shall be retained for a period as required by the regulatory authority.

Clean Air Filtration Services can manage all your HVAC maintenance requirements. We can maintain Maintenance records and ensure that your building, hospital or factory is compliant.

Commercial kitchen fires due to improper canopy cleaning or kitchen exhaust cleaning practises, continue to be a problem for restaurants across Melbourne with a number of high-profile fires occurring in 2017. These fires suggest the existence of an ‘awareness’ problem amongst facility managers, restaurant owners and service providers.

It’s important that all stakeholders understand the risks in order to save lives, businesses, and careers. Remember that it’s not just the restaurant that’s in danger. Many restaurants share complex duct exhaust systems with multi-storied residential developments. Commercial kitchen fires often spread through the duct systems and into these residential apartments.

A fire can start as a result of an issue with the kitchen canopy cleaning or a kitchen exhaust system cleaning practises. People often ask us how often kitchen exhaust systems should be professionally cleaned. However, often this is a difficult question to answer as it will depend upon kitchen usage and practises within the kitchen.

The Damage

Commercial kitchen exhaust fires can be intense with temperatures reaching 1,000 Degrees Celsius. Almost 90% of kitchen fires spread into kitchen canopy exhaust systems.

Many restaurants never re-open after a kitchen fire and many insurance policies reject claims when kitchen exhaust systems and canopies have not been adequately cleaned.

Greasy exhausts and canopies are a major reason why fires spread. Grease can leak out of duct joints causing a fire to spread to the outside of the ductwork and through a building.

Grease Filters Need To Be Managed

Grease filters are designed to collect grease and by their very nature are fire hazards. In fact, a recent ‘Bulletin’ by AIRAH (Australian Institute Of Refrigeration, Ait Conditioning & Heating) states that:

“A fire within the duct system generally occurs due to the ignition of flamable material that has built up at the grease re,mocal device (filters)” AIRAH, 20116

Proper maintenance and management of grease filters will prevent some fires from occurring. Clean Air Filtration offers Australia’s best Grease Filter Cleaning & Filter Exchange Service.

You Are Legally Responsible – We Are Here To Help

The Australian standard AS 1851-2012 outlines the minimum inspection, maintenance and record-keeping requirements for fire kitchen exhaust systems.

Clean Air Filtration understand and ensure your responsibilities are met. Leave the details to us and call us on   (03) 9303 9661

commercial kitchen cleaning

ACDC Lane Melbourne - Commercial Kitchen Fire Shook Them 'All Night Long'

commercial kitchen cleaning

Punters at a popular Melbourne restaurant were shaken 'all night long' in ACDC Lane last week due to a fire in exhaust ducts of the restaurant's commercial kitchen.

In addition, residents in a connected apartment building were evacuated as smoke from the fire billowed up through the duct system shared by both the commercial kitchen and the apartment block.

Fire sprinklers and fire alarms were set off throughout the residential building, with damage to both the commercial kitchen and apartment block.

Clean Air Filtration does not know the details relating to this particular fire. However, more generally, it is another reminder for both Restaurant Owners and Owner Corporations of how important it is to regularly clean commercial kitchens.

Many stakeholders do not realise that insurance policies relating to fire damage to restaurants and commercial kitchens are invalid if the commercial kitchen does not comply with commercial kitchen cleaning regulations as per Australian standard A.S. 1851-2005.

So, as well as dealing with the short-term issues relating to the fire clean up, restaurant owners may also fall foul of insurance companies and their fire policies.

In many cases, this will result in the closure of the restaurant as repair bills mount for both the restaurant and surrounding apartment blocks.

Owners Corporations of residential apartment buildings with commercial kitchens operating within the building should also take note. Avoidance is a better outcome than having to work through a ‘can of worms’ relating to a non-compliant commercial kitchen cleaning strategy.

Owners Corporations are advised to be ‘hands on’ when it comes to ensuring all commercial kitchens under their control have a compliant kitchen cleaning process in place.

Although the obligation to comply with commercial kitchen cleaning regulations lies with the restaurant owner, this knowledge will be no consolation if a kitchen fire guts your building.

Australian standard A.S. 1851-2005 outlines that a commercial kitchen duct exhaust system must be professionally cleaned in a twelve month period in order to comply.

Clean Air Filtration’s extensive range of duct cleaning and commercial kitchen cleaning services include:

  • Grease Cleaning and Kitchen Exhaust Cleaning Service
  • Full Commercial Kitchen Cleaning & Sanitising
  • Kitchen Grease Filter Exchange Service
  • Canopy and Duct Work System Cleaning
  • Commercial high-pressure steam cleaning
  • Programmed Maintenance Scheduling

Top 4 Reasons To Clean Your Air Ducts

  1. Protect against sickness
  2. Protect against litigation
  3. Protect against fire
  4. Reduce HVAC Operating costs

Our Preventative Maintenance Process

  1. Systematic Video Inspection
  2. Conduct Air Quality Tests
  3. Make Recommendations
  4. HVAC Cleaning
  5. Present comprehensive Final Report

Benefits of Duct Cleaning

  1. Reduction in Dust
  2. Reduction in Bacterias and Allergens
  3. Superior Indoor Air Quality

Commercial kitchen cleaning inclusive of kitchen canopy cleaning and kitchen exhaust cleaning is no easy job. However, Clean Air Filtration Services can take care of all your commercial kitchen cleaning requirements.

A kitchen canopy can develop a layer of grease and dirt on its surface. This results in an increase in bacteria growth and bad odours, causing an environmental health hazard.

Left unclean, a kitchen canopy and kitchen exhaust system can eventually collect enough grease to become an extreme fire hazard. Every year thousands of restaurant grease fires are reported in restaurants, with huge property losses, huge costs and fire marshal inspections.

Kitchen canopies and kitchen exhaust systems are thoroughly and professionally cleaned by our friendly staff.

Kitchens are de-greased through the use of manual or pressure hot wash systems. This includes the canopy through to the ductwork, fan and outlet.

To support this cleaning service a comprehensive filter exchange program and an air flow monitoring service is available.

Services are available 24 hours a day, seven days a week, allowing jobs to be completed with minimum disruption to a client’s business, staff and customers.

If a commercial kitchen has not been professionally cleaned in a twelve month period per A.S 1851 rev 2005 your building is non-compliant resulting in restaurant shutdowns or even no insurance for the fire .

Your first line of defence should be to have your commercial kitchen cleaned regularly. Clean Air Filtration Services will keep you in compliance with the latest industry standards and regulations.


  • Canopy Cleaning,
  • Ductwork Cleaning,
  • Fan / Extractor Fan cleaning
  • Outlet Cleaning
  • Filter exchange program
kitchen exhaust cleaning

A typical day in the life of a Clean Air Filtration employee involves getting your hands dirty – often very dirty.

Recently, after arriving at a Melbourne restaurant and inspecting the kitchen exhaust, ducts, and kitchen canopy, we could see it was one of those occasions:

It obviously hadn’t been cleaned for a number of years. There was nothing left to do except roll up our sleeves and get stuck in.

This situation is quite typical says Clean Air Filtration CEO Darren Broderick:

I’m not concerned for our guys. This experience was just another ‘day in the life’ for our employees who do a fabulous job cleaning some very dirty kitchen exhaust systems. Our guys are certainly willing and able to clean anything that they come across.

However, it’s the risk of fire that really worries me. By not cleaning the grease laden kitchen exhausts and ducts, the restaurant is opening themselves up to huge fire risks.

Several Melbourne restaurants have been consumed by kitchen fires in the last few years. These fires originated in kitchen flues and canopies.

To prevent fire hazards like these maintenance is required on a regular basis. It is important to be aware if the exhaust system has not been professionally cleaned in a twelve month period, as per A.S 1851 rev 2005, your building is non-compliant resulting in restaurant shutdowns or even no insurance for the fire.

Your first line of defence should be to have your kitchen exhaust cleaned regularly. Clean Air Filtration’s extensive range of duct cleaning services include:

  • Grease/ Kitchen Exhaust Cleaning Service
  • Electrostatic SMOG HOG Exchange and Service
  • Kitchen Grease Filter Exchange Service
  • Full Commercial Kitchen Cleaning / Sanitising
  • Canopy and Duct Work System Cleaning
  • Commercial High Pressure Steam Cleaning
  • Programmed Maintenance Scheduling

Top 4 Reasons To Clean Your Air Ducts

  1. Protect against sickness.
  2. Protect against litigation.
  3. Protect against fire.
  4. Reduce HVAC Operating costs.

Our Preventative Maintenance Process

  1. Systematic Video Inspection.
  2. Conduct Air Quality Tests.
  3. Make Recommendations.
  4. HVAC Cleaning.
  5. Present comprehensive Final Report.

Benefits of Duct Cleaning

  1. Reduction in Dust.
  2. Reduction in Bacterias and Allergens.
  3. Superior Indoor Air Quality.