Ventilation Hygiene Services

Do you know what is lurking in your ventilation systems?

Here at PH Water and Air Technologies we pride ourselves on our ventilation and air quality compliance services. We have an experienced team that conducts service on behalf of a varied client base. These services are as follows:


  • Fire Damper Testing and Maintenance
  • Grease Extract Cleaning
  • Ventilation Cleaning
  • Ventilation Hygiene Assessments
  • Indoor Air Quality Monitoring
  • Local Exhaust Ventilation (LEV)

These services are essential to making a safe working environment for our clients, there workforce and the public as well as meeting the legislative requirements.

Contaminants are no strangers to industrial Heating, Ventilation and Air Conditioning (HVAC) systems – Excessive build up of these contaminants ie Dust, Debris etc, can interfere not only with the efficiency and workload of the HVAC system, but also impacts the indoor air quality. This can be both costly to the plant equipment and associated HVAC system, but also the business and individuals.

The ventilation system can be home to several potentially harmful contaminants:

  • Particulates – Mixture of solids drifting in the air, consisting of dust, dander (skin flakes), soot, pollen and smoke particles.
  • Microbes – Bacteria, fungi, viruses, spores and mould.
  • Gases/Odours – Indoor gases release from furniture, carpets, cleaning chemicals, insulation etc.


These two services combined with the Indoor Air Quality provide a full overview of a building and a clear concise plan on how to rectify the issues to meet requirements. Poor air quality can cause a reduction in productivity and a rise in employee absence resulting in a cost to the business in poor productivity and lost days at work.


The Workplace (Health, Safety and Welfare) Regulations 1992 – require that effective provision should be made to ensure that every enclosed workplace is ventilated by a sufficient quantity of fresh or purified air. Where this ventilation is provided by mechanical means, the regulation require those mechanical ventilation systems to be maintained (including cleaned as appropriate) in an efficient state, in efficient working order and in good repair. Failure to carry out these duties is a breach of the regulations.

The primary legislation regarding ventilation systems is the Health and Safety at Work Act 1974 and the Management of Health and Safety at Work Regulations 1999.

Under this legislation it is identified that:

2(1) It shall be the duty of every employer to ensure, so far as is reasonably practicable, the health, safety and welfare at work of all employees.

3(1) It shall be the duty of every employer to conduct his undertaking in such a way as to ensure, so far as is reasonably practicable, that persons not in his employment who may be affected thereby are not thereby exposed to risks to their health or safety.

Workplace (Health, Safety and Welfare) Regulations 1992 state the following:

Regulation 6 – Ventilation

Effective and suitable provision shall be made to ensure that every enclosed workplace is ventilated by a sufficient quantity of fresh or purified air.

  • Any plant used for the purpose of complying with paragraph (1) shall include an effective device to give visible or audible warning of any failure of the plant where necessary for reasons of health or safety.

Ph Water and Air Technologies reports are carried out in line with the recommendations of The Association of British Insurers (ABI), BSRIA and TR19 Section 7 – HVCA Internal Cleanliness of Ventilation Systems.

British Standard BS EN 15780 provides benchmarks to define cleanliness and dirtiness.

Ventilation hygiene inspections are recommended to be completed annually, with the minimum frequency for AHU cleanliness inspections being 12 monthly as defined in BESA TR19. Ductwork is defined within the Quality classes as indicated in table1 below. TR19 provides guidelines for acceptable contamination levels within ventilation systems (Table 2 below)

Table 1 – Typical Applications of cleanliness quality classes (for ventilation systems)

Quality Classes Typical Examples
Low Rooms with only intermittent occupancy e.g. Storage Rooms, Technical Rooms
Medium Offices, Hotel, Restaurants, Schools, Theatres, Residential Homes, Shopping Areas, Exhibition/ Sports Building, General Working Areas in Hospitals & Industrial Spaces
High Laboratories, Treatment Areas in Hospitals & High Quality Offices


Table 2 – Acceptable Contamination Levels in Existing Ductworks

Quality Classes Acceptable Contamination Levels – Supply Ductwork Acceptable Contamination Levels – Re-circulation or Secondary Air Ductwork Acceptable Contamination Levels – Extract Ductwork
  D.T.T P.V.T D.T.T P.V.T D.T.T P.V.T
Low 90µm <4.5g/m2 120µm <6g/m2 180µm <9.0g/m2
Medium 60µm <3.0g/m2 90µm <4.5g/m2 180µm <9,0g/m2
High 12µm <0.6g/m2 60µm <3g/m2 180µm <9.0g/m2

We propose to provide a system wide survey from air intake through to extract. Ventilation hygiene report includes system information, diagrams and photographs. The surveys will include dust thickness readings where access to duct is possible.


A number of benefits may be derived from the cleaning of ventilation systems:

  1. Staff Efficiency – In extreme cases where “Sick Building Syndrome” has been experienced, there should be a noticeable drop of staff absenteeism and productivity will increase.
  2. Fire Safety – By reducing the contamination in the ducting, the combustion load of fire safety is greatly enhanced.
  3. Image – It will improve the environmental image of the company.
  4. Costs – There is a potential to reduce the running costs due to reduction in electrical loading and in certain instances fuel consumption.  Mechanical Efficiency – Is increased and a reduction in airborne dusts can help to protect sensitive equipment.

System Cleaning

Cleaning can be carried out using the following methods, in order to attain the specified level of hygiene

  • Hand scraping
  • Chemical wiping
  • Rotary Brush Cleaning
  • Chemical Decontamination

The techniques employed will be based upon the system type, accessibility and level of contamination.

On completion a comprehensive photographic report can be provided containing the following information:

  1. Details of the system(s) cleaned
  2. Pre-clean measurements (including sampling locations)
  3. Post-clean measurements (including sampling locations)
  4. Photographic records (Pre & Post)
  5. Additional works carried out (if any)
  6. COSHH data on any chemicals used
  7. Recommendations for future cleaning requirements (refer to table 17 below)
  8. Observations on the condition of the ductwork system
  9. A sketch or schematic of the system indicating access panel and testing locations and highlighting any un-cleaned areas with a written explanation as to why the area could not be accessed/cleaned (Refer to section 7.6 in TR19 for further information)