Air Purifier vs. Negative Air Machine

Although the air purifier and the negative air machine do similar jobs, there are clear cut differences in how these two machines work and are designed. Efficiency and results differ too as a result. Learn everything here.

What is an Air Purifier?

An air purifier helps to clean and improve indoor air quality. It filters out dirt particles, chemicals, and gases in the places it used. Some models come with an activated carbon filter which helps to reduce odours, and HEPA filters to catch fine particles and organic compounds.

What is a negative air machine?

A negative air machine can serve the same purpose as an air scrubber when positioned within a room to recirculate air with the necessary filtration. However, a negative air machine can be used for other purposes such as ductwork cleaning, dust control and damp removal. Negative air machine’s fans are ideal for ductwork cleaning because they can pull large volumes of air out of spaces, such as a long duct, despite a high resistance. As a result, negative air machines are commonly used in construction, asbestos abatement and ductwork cleaning industries. Negative air machines may be positioned throughout a construction site, particularly during demolition or strip out, to capture dust released from the works. In asbestos, negative air machines equipped with HEPA filters can be used to control pressure and airflow within sealed enclosures.

The difference in design and function

The air purifier is often designed as a tower, to be positioned within a room to clean the air. Depending on the size and shape of a room multiple purifiers may be needed to deliver the required air changes per hour (ACH). This is how many times the air inside the room is passed through the purifier filters per hour. For optimal results, purifiers should be positioned correctly in rooms to avoid “dead spots”, meaning air which isn’t circulating. 

The negative air machine is designed to be portable, it will need to be regularly moved and repositioned as work activities develop. Flexible hoses can be connected to both the inlet and outlet of the machine, this means air can be collected and released precisely.

Occasions when the negative air machine will serve you best

Mould remediation

During the removal of moulds, spores often become air-born and may escape from the room through openings and spread to other parts of the building. The use of a negative air machine leads to negative air pressure inside the affected room. The only way out for contaminated air is out through the ducted filtering machine.

Construction Dust Control

The vacuum effect, as mentioned earlier, accelerates the filtration process of particles suspended in the air. When positioned correctly around a site and close to dust-producing tools or processes the spread of dust throughout the site is reduced. Many processes during demolition and construction produce and release dust, water suppression and built-in tool filtration is not enough on its own to control the dust release.


The HEPA negative air machine can lead to a safer temporary isolation room. There is a reduced risk of spreading infectious diseases because the machine makes the room a negative environment.

Occasions when the air purifier will serve you best

At Home

Purifiers are ideal for small spaces and rooms such as bedrooms, kitchens and offices. Household purifiers are a particularly good idea when living in city centres or highly polluted areas. Residents beside a bus stop or busy road have an increased risk of pollutants in their indoor air.

At work and in the office

Small workplaces such as studios, private clinics, nail bars, hair salons may all be well served by a purifier. A household office or shed is also no problem, which is great news as many more people are now working at home through the COVID-19 pandemic.