Local Exhaust Ventilation – Why is it important?

Laboratories are dynamic environments where various hazardous substances and processes are present. Ensuring the safety and well-being of laboratory personnel is of paramount importance. A safe working environment promotes productivity, protects human health, and minimizes the risk of accidents and exposure to hazardous substances.  

Local exhaust ventilation (LEV) is a critical engineering control system used in laboratories to control and remove airborne contaminants. It involves the use of specialized equipment, such as capture hoods, ductwork, exhaust fans, and filtration units, to effectively capture, control, and remove hazardous substances generated during lab processes.  

This blog aims to provide a comprehensive understanding of local exhaust ventilation in laboratory settings. It will explore the components, working principles, and design considerations of LEV systems. Furthermore, it will highlight the importance of LEV in controlling hazardous substances, protecting laboratory personnel, and complying with occupational safety and health regulations. 

Understanding Local Exhaust Ventilation (LEV)  

A. Definition and Purpose of LEV 

Explanation of local exhaust ventilation 

Local exhaust ventilation is an engineering control system that uses specialized equipment to capture and remove airborne contaminants generated during lab activities. It works by capturing the contaminants at the source and transporting them away from the breathing zone of laboratory personnel.  

Purpose of LEV in laboratory settings 

The primary purpose of LEV in laboratories is to protect workers from exposure to hazardous substances and maintain a safe working environment. It helps prevent the spread of airborne contaminants, reduces the risk of respiratory issues and other health problems, and ensures compliance with occupational safety and health regulations. 

B. Components of LEV Systems 

Capture Hood or Canopy 

Capture hoods or canopies are devices designed to capture contaminants at their source. They are placed close to the point of emission, such as fume hoods or workstations, to effectively capture airborne substances before they disperse into the laboratory.  

Ductwork and Airflow Control Devices 

Ductwork forms the network of pipes that transport the captured contaminants from the capture hoods to the exhaust fan or filtration units. Airflow control devices, such as dampers and valves, are installed in the ductwork to regulate the airflow and control the direction of contaminants.  

Exhaust Fan 

The exhaust fan creates negative pressure within the LEV system, facilitating the movement of air and contaminants through the ductwork. It helps maintain a consistent airflow and ensures efficient removal of hazardous substances from the laboratory.  

Filtration and Treatment Units 

Filtration and treatment units are responsible for removing or neutralizing contaminants before discharging the air to the outside. They may include filters, scrubbers, or other treatment mechanisms, depending on the nature of the contaminants.  

Discharge Point 

The discharge point is the location where the treated air is safely released outside the laboratory. It is important to ensure that the discharged air does not pose a risk to the environment or nearby personnel. 

C. Working Principles of LEV Systems 

Contaminant Capture and Containment 

LEV systems are designed to capture contaminants at their source, preventing their dispersal into the laboratory. The capture hoods or canopies are strategically placed to effectively capture and contain the contaminants, allowing for their subsequent removal.  

Airflow and Ventilation Control 

LEV systems create a controlled airflow pattern within the laboratory, directing the contaminated air towards the capture hoods and through the ductwork. Proper airflow control ensures that the contaminants are effectively transported and removed from the laboratory , minimizing their potential for exposure to laboratory personnel.  

Filtration and Treatment of Contaminants 

After the contaminants are captured and transported through the ductwork, they pass through filtration and treatment units. These units are designed to remove or neutralize the contaminants, ensuring that the discharged air meets the required safety standards before being released outside the laboratory.  

Safe Discharge of Air 

The treated air is safely discharged through the designated discharge point. It is crucial to ensure that the discharge point is located in a safe area where the released air will not pose any risks to the environment or nearby personnel. 

Importance of Local Exhaust Ventilation in Laboratories  

A. Control and Removal of Hazardous Substances 

Prevention of Exposure to Chemicals and Toxic Substances 

LEV systems play a vital role in controlling and removing hazardous chemicals and toxic substances that are present in laboratory environments. By capturing and removing these substances at their source, LEV systems significantly reduce the likelihood of laboratory personnel inhaling or coming into contact with harmful substances.  

Minimizing the Spread of Airborne Contaminants 

Laboratory processes can generate airborne contaminants, such as vapors, gases, dust, or biological agents. These contaminants can easily spread throughout the laboratory, posing risks to the health and safety of personnel. LEV systems effectively capture and contain these contaminants, minimizing their spread and reducing the potential for cross-contamination. 

B. Protection of Laboratory Personnel 

Ensuring Worker Safety and Health 

The implementation of LEV systems is crucial for safeguarding the health and well-being of laboratory personnel. By removing hazardous substances from the breathing zone, LEV systems help prevent acute and chronic health effects associated with exposure to toxic chemicals or biological agents.  

Reducing the Risk of Respiratory and Health Issues 

Exposure to airborne contaminants in laboratories can lead to respiratory problems, allergies, sensitization, and other health issues. LEV systems mitigate these risks by capturing and removing contaminants, reducing the inhalation of harmful substances and minimizing the potential for adverse health effects. 

C. Compliance with Occupational Safety and Health Regulations 

Regulatory Standards for LEV in Laboratories 

Many regulatory agencies, such as the Occupational Safety and Health Administration (OSHA) and local health departments, have specific regulations and standards pertaining to LEV in laboratory settings. Compliance with these regulations is essential to ensure a safe and healthy work environment and to avoid penalties or legal consequences.  

Legal and Ethical Obligations for Workplace Safety 

Employers have a legal and ethical responsibility to provide a safe working environment for their employees. Implementing LEV systems demonstrates a commitment to workplace safety, protects employees from harm, and upholds ethical obligations to prioritize the health and well-being of laboratory personnel. 

Design and Implementation of Effective LEV Systems  

A. Conducting a Site Assessment 

Before designing and implementing an LEV system, a comprehensive site assessment should be conducted. This assessment involves evaluating the hazards and risks present in the laboratory, understanding the specific requirements of the processes and substances used, and identifying the appropriate LEV solutions. 

B. Design Considerations for LEV Systems 

Proper Placement and Configuration of Capture Hoods 

Capture hoods should be strategically located to effectively capture contaminants at their source. Considerations such as the type of process, proximity to emission points, and the movement of laboratory personnel should be taken into account when determining the placement and configuration of capture hoods.  

Ductwork Design and Airflow Calculation 

The design of the ductwork is crucial for ensuring efficient airflow and effective transport of contaminants. Factors such as duct size, routing, and proper calculation of airflow velocities should be considered to minimize pressure drop, optimize capture efficiency, and maintain the required airflow rates.  

Fan Selection and Sizing 

Selecting the appropriate exhaust fan is essential for maintaining proper airflow within the LEV system. Factors such as the volume of contaminants generated, the length and configuration of the ductwork, and the static pressure requirements should be considered when selecting and sizing the fan. Proper fan selection ensures adequate airflow to capture and remove contaminants effectively.  

Filtration and Treatment Options 

The choice of filtration and treatment units depends on the nature of the contaminants generated in the laboratory. Different filters, scrubbers, or treatment mechanisms may be required to remove specific substances or neutralize chemical or biological agents. Selecting the appropriate filtration and treatment options ensures the effective removal of contaminants before discharging the air. 

C. Installation and Maintenance of LEV Systems 

Professional Installation and Commissioning 

The installation of LEV systems should be carried out by qualified professionals who are experienced in laboratory ventilation systems. Proper installation ensures that the system functions optimally and meets regulatory requirements. After installation, thorough commissioning and testing should be conducted to verify the performance and effectiveness of the LEV system.  

Regular Inspection, Testing, and Maintenance 

Regular inspection, testing, and maintenance are crucial for the ongoing performance and efficiency of LEV systems. This includes checking for leaks, monitoring airflow rates, inspecting and replacing filters as needed, and ensuring that all components of the system are functioning properly. Routine maintenance helps identify and address any issues promptly, ensuring the continued effectiveness of the LEV system.  

Training and Education for Lab Personnel 

Lab personnel should receive adequate training and education on the proper use and maintenance of LEV systems. This includes understanding the purpose of the system, knowing how to operate the capture hoods effectively, recognizing signs of system malfunction, and reporting any concerns or issues. Proper training promotes a culture of safety and ensures that personnel can utilize the LEV system correctly. 

Benefits and Challenges of Local Exhaust Ventilation  

A. Benefits of LEV Systems 

Improved Worker Safety and Health 

Effective LEV systems significantly reduce the exposure of laboratory personnel to hazardous substances, thereby improving worker safety and health. By capturing and removing contaminants at the source, LEV systems minimize the risks of acute and chronic health effects associated with exposure to toxic substances.  

Enhanced Contaminant Control and Laboratory Hygiene 

LEV systems help maintain a clean and hygienic laboratory environment by controlling and removing airborne contaminants. This contributes to improved laboratory hygiene, reduces cross-contamination risks, and ensures the integrity of experiments and research conducted in the lab.  

Compliance with Regulatory Standards 

Implementing LEV systems ensures compliance with occupational safety and health regulations, as well as local regulatory standards for laboratory environments. Compliance demonstrates a commitment to workplace safety, avoids potential penalties, and upholds legal obligations. 

B. Challenges and Considerations 

Design and Engineering Complexity 

Designing and engineering an effective LEV system requires expertise and careful consideration of factors such as airflow patterns, capture efficiency, and treatment options. The complexity of the design process can pose challenges, necessitating the involvement of qualified professionals with knowledge of laboratory ventilation systems.  

Ongoing Maintenance and Upkeep 

LEV systems require regular maintenance to ensure optimal performance. Filters may need to be replaced, ductwork inspected, and fans serviced periodically. The ongoing maintenance and upkeep can be time-consuming and may require dedicated resources and scheduling to ensure the system operates effectively.  

Cost Considerations and Budgeting 

Implementing an LEV system involves costs related to equipment, installation, commissioning, and ongoing maintenance. Organizations must carefully budget for these expenses, considering the size of the laboratory, the complexity of the system, and the specific requirements for capturing and removing contaminants. It is essential to balance the cost of implementation with the potential benefits and long-term savings in terms of worker health and regulatory compliance. 


Implementing effective LEV systems is crucial for maintaining a safe and healthy laboratory environment. By controlling and removing hazardous substances, LEV systems protect the health and well-being of laboratory personnel, reduce the risk of respiratory issues and other health problems, and ensure compliance with occupational safety and health regulations.  

To create a safe and healthy laboratory environment, it is essential to prioritize the implementation of effective LEV systems. This involves understanding the components and working principles of LEV, conducting site assessments, designing and engineering systems, professional installation and commissioning, regular maintenance, and providing training and education for lab personnel. By investing in LEV systems, organizations can ensure worker safety, protect human health, maintain regulatory compliance, and promote a culture of safety in the laboratory.  

In conclusion, local exhaust ventilation plays a critical role in laboratory safety. By effectively capturing and removing airborne contaminants, LEV systems protect the health and well-being of laboratory personnel, prevent exposure to hazardous substances, and ensure compliance with occupational safety and health regulations. Implementing robust LEV systems is an investment in the safety, health, and productivity of laboratory environments. 

Kewaunee, the global leader in total laboratory solutions, empowers organisations to achieve competitive advantage through safe, efficient, and contemporary laboratories. In existence since 1906, Kewaunee powers the laboratories for over 5,000 customers in more than 100 countries.

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