Comparing air purifiers for schools

If you’re a school looking for an air purifier to help combat the risk of COVID-19 infection, you’re likely to have read the Room Air Cleaner Guidance for Schools from the Department of Education.

phs is an expert in room air quality and air purifiers but we appreciate you may not be. With all of the information out there and competing products, it can be a lot to digest. To help, phs has created a guide to our range of cutting-edge air purifiers detailing everything you need to be considering. To give you the complete rundown, we’ve cross-referenced this article with the Department of Education guidance, addressing every point listed. This includes information about the efficiency of our air purifiers, filter types, noise levels, maintenance requirements as well as all the additional features offered. And if you’re looking to fill in the Department of Education air cleaner check list, we’ve even gone as far as filling it in for our range of air purifiers. It’s all part of our aim to make your experience straightforward and to meet all of your needs.

But first, a quick introduction. phs’ AERAMAX PROFESSIONAL range of air purifiers captures 99.97% of airborne contaminants, emitting cleaner, fresher air back into the room.  Vitally, our AERAMAX PROFESSIONAL III and IV purifiers have been scientifically proven to be effective against COVID-19. Independent laboratory tests confirm both eliminate aerosolised concentrations of SARS-CoV-2 (COVID-19) by 99.9999% in a single air pass test. And our air purifiers aren’t just valuable during the pandemic; they also remove other viruses and infections including colds, flu, TB, measles, mumps, whooping cough and chicken pox. That’s on top of their effectiveness in removing  dust, mould and odours, pollen, allergens and VOCs as well as tackling the growing issue of indoor air pollution.


The phs AERAMAX vital statistics:

1. Matching the cleaning unit to the room in which it is to be located

One important metric for air purifiers is how many times they can change the air within a room, per hour. This is known as the ‘air change rate per hour’ (ACH).

AERAMAX are the most powerful wall-mounted commercial air purifiers currently available. As such, we can work with you to achieve whatever air change rate you are looking for. As standard, we base our recommendations on a minimum of three air changes per hour.

  • AERAMAX PROFESSIONAL III will achieve an average of three air changes per hour in a room that is 65m3
  • AERAMAX PROFESSIONAL IV will achieve an average of three air changes per hour in a room that is 130m3

For larger rooms, or to increase the air change rate, we would recommend adding an additional unit.

As the guidance states, there is no one-size-fits-all solution to air purifiers so phs’ air quality experts will visit your school to assess your exact requirements. From this, we can recommend the right solution for you, including product type, quantity and location to make sure it’s working at its most effective.


2. The efficiency of the air cleaner

The air change rate is determined by two key factors; the volume of air in your room and how effective the air purifier is at removing particles from the air – known as the clean air delivery rate (CADR). So the higher the CADR, the more particles it can remove per hour. A higher CADR also means the unit is capable of cleaning larger rooms.

As the guidance details, the equation to calculate the air change rate is:

ACR (cleaning) = CADR ¸ Volume of air in a room

While we’ve done the maths for you above to demonstrate the maximum room sizes for an air change rate of three for our AERAMAX units, you can use the below stats to find out the air change rate in your classroom. Remember, you can add a second or even third unit for larger spaces or to up the number of air changes per hour:

  • AERAMAX PROFESSIONAL III: maximum airflow of 374m3/hr
  • AERAMAX PROFESSIONAL IV maximum airflow of 748m3/hr.


3. Filter types in the unit

An good air purifier relies on a robust filtration process. This is an area which you should pay particular attention. Filters are how a unit physically traps and removes particulates from the air.  The Department of Education states air cleaners usually have at least two filters. However, phs’ air purifiers have four filters for the ultimate reassurance in air cleaning. As cited, air cleaners with a HEPA filter are the most effective but be warned that some devices are labelled as HEPA-type filters which are not as effective. phs can confirm its air purifiers are true HEPA filters.

Our four-stage filtration process:

  • Stage 1: The pre-filter captures the larger particles and contaminants such as dust.
  • Stage 2: A carbon filter adsorbs odour molecules and VOCs which attach themselves to the surface of the activated carbon.
  • Stage 3: The true HEPA filter captures airborne particles such as germs and viruses, bacteria, mould and even fibrous microplastics. The filter has been certified to capture SARS-CoV-2, the virus that causes COVID-19. As part of the manufacturing process, the HEPA filter is impregnated with an antimicrobial coating to ensure mould and bacteria cannot multiply and grow.
  • Stage 4: Finally, there is a bipolar ioniser filter which electrically charges any remaining minute particles to ensure they attach themselves to other particles and are caught.


4. Noise levels

When you’re teaching in a classroom, you’ll of course want to be mindful of the noise level of your chosen unit. The noise level of our AERAMAX air purifiers are as follows:

Fan level




38 decibels

42 decibels


41 decibels

44 decibels


48 decibels

51 decibels


52 decibels

53 decibels


67 decibels

68 decibels

We recommend using fan speed 3 as the average when a room is occupied. The AERAMAX will adjust between fan speeds 2, 3 and 4 during operation. Fan level 5 is only activated when the room is empty.

For a point of comparison, 30 decibels is equivalent to a quiet whisper, 40 decibels is a refrigerator humming, 50 decibels is moderate rainfall and 60 decibels is the noise of dishwasher running.


5. Maintenance

In a standard education setting, an AERAMAX filter will need changing just once a year. If you’re using them in a particularly high footfall location such as a washroom or changing area then they may need changing more frequently; around two or three times a year.

The high quality AERAMAX filters are not washable and will be replaced with new filters as part of the service from phs with no additional service or filter costs – so you won’t face any unexpected expenditure to keep one of our air purifiers up and running. All you’ll pay is one up-front cost which includes installation, filter changes and a warranty for the full term of either a three or five year contract. In comparison, many air purifiers are only covered by either a one or two year warranty. And don’t forget phs also offers a free air quality consultation and audit to review your setting and potential solutions with no obligation. 


6. Additional features

Every air purifier is different and phs is proud of the credentials of its AERAMAX range. Here are the added extras that are included as standard with our air purifiers:

  • Research tested: AERAMAX are the most powerful wall-mounted commercial air purifiers currently available and are scientifically proven to remove COVID-19.
  • Wall-mountable: phs’ AERAMAX air purifiers can be free standing or wall mountable; ideal if you’re short of floor space or if you want to keep the unit and its power cords out of the way, reducing hazards. This also allows you to place the air purifier off ground level, maximising locations with optimal airflow. Your phs technician can advise of the best location and will install your units.
  • Display features: As standard, AERAMAX units come with a filter replacement light so you can request a free service visit from a phs technician whenever needed. They also feature air quality and activity sensors.
  • Effectiveness: AERAMAX PureView technology gives you the power to see your air purifier at work. EnviroSmart laser sensors continually monitor air quality in the room, activating the filtration system when harmful particles are present. The digital display indicates the percentage of particles being cleaned or can display the PM2.5 particle count, an industry standard for air quality measurement. This feature makes the invisible, visible; demonstrating the effectiveness of your machine and how clean the air in your room is.


Quick Summary Check List

For more information on air purifiers and air cleaning in education, speak to phs’ air quality experts today for a free consultation :

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