Most people hear about TR19® in the context of kitchen extracts and grease. But the same BESA specification has a second part, TR19® Air, for the general ventilation systems found in almost every modern building: the ducts, grilles and air handling units that bring fresh air in and take stale air out.
Those systems collect dust, debris and sometimes moisture over the years. TR19 Air sets out how to inspect them, when to clean them and how to prove it’s been done. This guide explains what it covers, which buildings it suits and how the inspection-led approach works.
TR19 Grease and TR19 Air
BESA split its TR19 specification so each part could focus on its own risk:
- TR19® Grease deals with grease in kitchen extract systems, which is mainly a fire risk.
- TR19® Air deals with general supply and extract ventilation, where the concerns are air quality, hygiene and the system working as designed.
BESA’s guide to ventilation hygiene standards explains that TR19 applies to general supply and extract systems beyond the kitchen, using a risk-based, inspection-led approach to cleaning.
Which systems TR19 Air covers
TR19 Air applies to the ventilation in buildings such as:
- offices and retail units;
- schools, colleges and universities;
- hospitals, clinics and care homes;
- hotels, leisure centres and public buildings.
Within those buildings, it covers supply ductwork, extract ductwork, grilles and diffusers, and the air handling units that drive the system. Toilet and general extract systems are included too. Our offices and retail and hospitals and care homes pages explain how the work fits around each kind of site.
What builds up in ventilation ducts
General ventilation doesn’t carry grease, but it isn’t clean either. Over time ducts can collect:
- dust and fibres drawn in from outside or from inside the building;
- debris left from construction or refurbishment;
- dirt that passes damaged or poorly fitted filters;
- moisture and condensation in some parts of the system.
The result can be reduced airflow, dust blown back into rooms, smells and a system working harder than it should. In buildings used by vulnerable people, such as hospitals and care homes, the standard of cleanliness expected is higher, and the inspection should reflect that.
Inspection first, then cleaning
TR19 Air doesn’t set a fixed calendar in the way the TR19 Grease table does. Instead it’s risk-based. The system is inspected, the condition of the ductwork and plant is assessed, and cleaning is carried out where the inspection shows it’s needed.
That means the first step is a survey: looking at the ductwork through access panels, checking the AHU, and recording what’s there with photos. The findings decide what gets cleaned and how often it should be checked again. The kind of building matters too; a hospital ward has different needs from an open-plan office.
The survey should also check the access available. Like kitchen extracts, ventilation ductwork can only be inspected and cleaned where there are access panels. Parts that can’t be reached should be recorded, so you know where the gaps are and can plan to close them.
Need it done? Duct Doctor cleans and tests kitchen extract and ventilation systems across London and the South East, with a certificate and photo report after every clean. Get a fixed quote.
Air handling units
The AHU is the heart of most supply systems, and it’s often the dirtiest part. Inside you’ll find filters, heating and cooling coils, drain trays, fans and internal panels. Common problems include:
- clogged or bypassed filters;
- dirt on coils, which cuts their performance;
- standing water in drain trays;
- dust on fans and internal surfaces.
Our AHU cleaning service covers all of these, usually during a planned shutdown so the building isn’t left without air for long, and our AHU cleaning guide goes into more detail.
The law and TR19 Air
As with the grease specification, TR19 Air isn’t law. BESA links ventilation hygiene to several pieces of legislation, including the Regulatory Reform (Fire Safety) Order 2005, the Health and Safety at Work etc. Act 1974, the Building Safety Act 2022 and the Food Safety Act 1990.
In practice, keeping ventilation clean and working is part of providing a safe, healthy building. For a facilities manager, a record of regular inspection and cleaning also helps answer questions from tenants, staff and auditors about the air in the building. TR19 Air gives you a recognised way to plan that work and record it.
The Vent Hygiene Register expands
BESA’s Vent Hygiene Register began with kitchen extract cleaning. From March 2026 it expanded to cover TR19 Air as well, so general ventilation cleaning can be certified in the same way as kitchen extract work.
BESA also advises that certificates should record the date, the location and the technician, and that they should be kept in the building’s maintenance log. That makes it easier for facilities managers to show what’s been done, and when.
Fire dampers in ventilation systems
Ventilation ductwork in larger buildings often passes through fire-resisting walls and floors, which means fire dampers. Dust and corrosion can stop them closing. BESA says they should be tested at least annually.
It often makes sense to test dampers while access panels are already open for a ventilation inspection or clean. It saves a second visit, and the same report can record the condition of the duct and the result of each damper test. See our fire damper testing guide.
How Duct Doctor approaches TR19 Air
Duct Doctor starts every ventilation job with a survey. We inspect the ductwork and plant, take photos, and tell you what needs cleaning and what doesn’t. Then we give a fixed quote, clean the system out of hours where needed, and issue a certificate and photo report. We work across London and the South East, in occupied buildings as well as empty ones.
Our ventilation cleaning page has more detail, or get in touch to arrange a survey.
Quick answers
What is TR19 Air?
The part of BESA’s TR19® specification covering general supply and extract ventilation, as opposed to kitchen extracts, which are covered by TR19® Grease.
How often should office ventilation be cleaned?
TR19 Air is risk-based. The system is inspected and cleaned when the inspection shows it’s needed. The building’s use affects how often it should be checked.
Does TR19 Air include air handling units?
Yes. AHUs, supply and extract ductwork, grilles and diffusers are all part of the system.
Is TR19 Air a legal requirement?
No. It’s a BESA specification. It helps building owners meet wider duties under health, safety and fire legislation.
Can TR19 Air cleaning be certified?
Yes. BESA’s Vent Hygiene Register expanded to cover TR19 Air from March 2026.
Related services
- Ventilation duct cleaning
- Air handling unit cleaning
- Fire damper testing
- TR19 inspections and grease testing
More advice
- Air Handling Unit Cleaning: A Practical Guide
- Fire Damper Testing: A Guide for Building Owners
- TR19 Explained: Kitchen Extract Cleaning Standard
- How to Choose a Kitchen Extract Cleaning Contractor
- All advice
This guide is general information. It isn’t legal or insurance advice: check your own policy wording and lease, and speak to a qualified adviser about your fire risk assessment.