Local Exhaust Ventilation (LEV) Checking Frequency

Local Exhaust Ventilation (LEV) is equipment use or install in a workplace to gauge the chemical exposures which are hazardous to health. It captures contaminants before it disperses into the working/workroom environment. The pollutants can be in the form of dust, aerosol and other hazardous chemical gas or substances.

It is part of the local regulator’s requirement to control exposures in a workplace to include local exhaust ventilation, water spray, and other airborne chemical removal and containment equipment.


Evaluation of risk assessment on the whole ventilation system is crucial as it affects Local Exhaust Ventilation performance.

The Local Exhaust Ventilation system has to be checked, tested and examined at a frequent interval to ensure efficiency and functionality. It consists of checking the system’s physical condition, utilising the system, smoke tube tracer test, identifying any obstruction to the air-flow, the shape of the hood, and inspection of cleaner device and fan’s motor.

Local regulation may stipulate as provision for any control equipment such as LEV to be checked and tested by competent personnel.


The frequency varies following local or country requirements. Other practices/localities have mandated that the system should be checked every 14 months or more frequently if deemed fit by the manufacturer.

simple routine check needs to be undertaken during the operations of the LEV. Regular checks ensure that performance measurement is being compared against its instalment data, on-going performance, detection of any wear and tear from the usage, or any misplaced section of the system. Early detection in the event of a gap or failure in the network can help provide speedy diagnosis and action.

How Often Should Local Exhaust Ventilation (LEV) be Checked?

An annual performance testing is undertaken to ensure that the LEV system continues to operate per its initial design to achieve adequate control. The testing should be performed by competent personnel in the operations of the LEV system. The appointed qualified personnel are Occupational Hygienist or Ventilation Engineer or Outside/Professional Contractor who must conduct the standard testing format commissioned by the Authority.

There are three (3) stages of annual testing: Thorough Visual and Structural Examination, Technical Performance and Control Effectiveness. 

The record or logbook of the said checked has to be retained for a minimum of 5 years. The journal should indicate the initial design, performance monitoring and check for any modification made to the system to show the system’s progress.


A plan for periodic maintenance at regular intervals is an essential aspect of the LEV operations. The inspection ensures the operational efficiency of the LEV at least at par with the latest instalment. Also, the system is in excellent and operating conditions. This is a very good options when it comes to Bathroom Ventilation, according to Jon from Bathroom Renovations Newcastle. Maintenance schedules depend on the intensity and usage of the design/LEV, which should not be more than 14 months.

A contingency plan or policy must be developed in case of breakdown or power failure and approved by the relevant Authority. This is to ensure the operational and efficiency of the system.


A comprehensive or detailed logbook stipulating the frequency of testing/s, the checking/testing results, and any replacement of part/s in the system have to be recorded and retained for inspection/s by the authority/regulator.  

It has to be made available upon request by the relevant Authority or regulator. The results must include the design, construction, testing, inspection, examination, maintenance, and sufficient training available for employees specifically involved with the system’s operations. A record of the activity or retraining has to be maintained and updated.

Audit Review

A periodic review to be conducted by an independent audit to highlight any discrepancy and action for improvement of the system to be undertaken. Assurance of any Control of Substances Hazardous to Health Regulations (COSHH) requirement for assessment and maintenance has been complied with and adhered to. This is part of the maintenance efficiency of the system.


The local exhaust ventilation system’s effectiveness and efficiency depend on its design, regular maintenance, proper usage, and routine inspection of the system.

What is the Exhaust Ventilation System?

Natural ventilation is the standard ventilation system that allows fresh outdoor air to flow into the house to replace indoor air. Natural ventilation is no longer efficient, especially for homes that are tightly sealed for energy efficiency. Opening windows and doors are no longer regarded as the norm. Therefore, air infiltration has become the principal mode of ventilation for homes.

Natural ventilation is uncontrollable, thus undependable to ventilate the whole house uniformly. Natural ventilation depends on the house’s airtightness, outdoor temperatures and other factors. A tightly sealed house may have insufficient natural ventilation whilst a place with high air infiltration rates is costly to maintain.

Houses or buildings become energy efficient, given concern about the occupants’ health and well-being and low indoor air quality (IAQ). Indoor air quality can be unhealthy and has many adverse effects, including allergies, asthma, cancer, liver and kidney failures.

Mechanical ventilation is the solution for energy-efficient homes to maintain their indoor air quality. There are four basic mechanical whole-house ventilation systems, namely Exhaust, Supply, Balanced and Energy Recovery. The efficient ventilation system for a house depends on the climate and the building structure.

Illustration of Exhaust Ventilation System

Exhaust Ventilation 

In summary, Exhaust Ventilation is inexpensive and straightforward to install. It works well in the cold climate. It is not suitable for humid climates, relies on random air leakage, may increase heating and cooling costs, requires a mixture of indoor and outdoor air to avoid drafts in cold weather, and can draw pollutants into living space back-drafting in combustion appliances. 

What is the Exhaust Ventilation System?

How it works – It works by depressurizing the house. It exhausts air from the make while air infiltrates through leaks in the building shell and intentional, passive vents. It works well in cold climates, as in warm, humid climates, and the depressurizing can draw moist air into the building wall cavities where it may condense and cause moisture damage.

It is inexpensive and straightforward to install. It consists of a single fan connected to a central location in the house. For better design, the fan is connected to ducts from several rooms where pollutants are generated, presumably the bathroom/s. Adjustable, passive vents through windows or walls can be installed in other rooms to flow fresh air compared to total dependence on leaks in the building envelope. However, passive vents require more considerable pressure differences than those using ventilation fans to work efficiently.

A simple approach would be the function of spot ventilation exhaust fans installed in the bathroom and operate continuously.

Primary Concerns of Exhaust Ventilation

The system may not only draw fresh air into the house but may remove pollutants including:-

  • Radon and moulds
  • Dust 
  • Fumes from the attached garage
  • Flue gases from a fireplace or fossil-fuel-fired water heater and furnace

The pollutants are more of concerns during bath fans’ operations, range fans, and clothes dryers with the Exhaust Ventilation system’s subsequent procedures, which will also depressurize the house. It can also contribute to higher heating, and cooling cost as the system does not remove moisture from the air before it enters the house.