Airborne surface disinfection equipment for use in laboratories
- ohaution1
- Jun 1
- 5 min read
ASD (Airborne surface disinfection) in laboratories and Industries has become a top priority for ensuring the safety and quality of research conducted in these sensitive environments. Given growing concerns about contamination and the spread of pathogens, it is essential to have technologies adapted to the technical constraints (volumes, configurations, frequency, objectives, traceability, etc.). This article presents ASD equipment suitable for laboratories, its advantages, and concrete examples of its use.
Why is ASD relevant?
Environmental biology in a laboratory can directly impact experimental results and operator safety. Laboratories, whether biological, chemical, or medical, are often exposed to pathogens, volatile chemical compounds, and other contaminants. Here are some reasons why ASD is essential:
Infection prevention : Biomedical research laboratories, for example, frequently handle pathogens. Effective surface disinfection can reduce the risk of hospital-acquired infections.
Sample protection : Contaminants present in the air and on surfaces can alter test results. Proper disinfection helps preserve sample integrity.
Regulatory compliance : Many laboratories must adhere to strict rules and standards regarding surface contamination control. Disinfection equipment helps ensure this compliance.
Types of H2O2 surface disinfection equipment
There are several types of surface disinfection equipment suitable for laboratories. Each has its own characteristics and advantages. Here is an overview of the most common options:
Thermal Vaporization (VHP)
Thermal vaporization relies on the phase transition of hydrogen peroxide between 110 and 130°C. At these temperatures, a 30-35% H₂O₂ solution efficiently transitions from a liquid to a vapor state. The system integrates a heated reservoir containing the solution, a sintered porous tube regulating the flow rate, a thermally insulated vaporization chamber, and a forced aeration module. The porous tube is the key innovation: the liquid percolates through the porous wall (10-100 μm) and forms a thin film at the external interface where heating causes near-instantaneous vaporization.
The major advantage lies in its independence from relative humidity. Unlike aerosols, hot steam completely saturates the chamber volume with gaseous peroxide, ensuring homogeneous exposure of all surfaces, including complex or occluded areas. This volumetric saturation, combined with slow but complete molecular diffusion, guarantees a biocidal efficacy exceeding 95%, achieving a 6-log reduction in bacterial spores.
The system is designed for critical environments: pharmaceutical production isolators, ISO 5-6 cleanrooms, aseptic transfer airlocks, and biosafety level 3-4 laboratories. Its reliable performance justifies the high acquisition cost (€50,000-€150,000) and consumable costs (€5,000-€10,000 annually). Limitations include high temperatures (risk of degradation of heat-sensitive polymers), long cycle times (60-120 minutes), complex maintenance (sensor calibration, wear of porous tubing), and substantial energy consumption.
Rotating Disc
The rotating disc generates a centrifugal mist. Operating at 50,000 rpm, the stainless steel disc creates a centripetal acceleration of approximately 28 g. Liquid H₂O₂ (5-7% concentration) is fed beneath the disc via a peristaltic pump and forced against the surface by centrifugal pressure. The extreme shear forces fragment the liquid film into droplets with a median diameter of 30-50 μm and a geometric standard deviation of 1.8-2.2. These relatively large droplets settle rapidly (10 μm in ~70 min).
The system offers volumetric flexibility (0.5-25 m³), rapid injection (5-15 min), and portability. The acquisition cost is very low (€5-20k). However, the distribution is not homogeneous: the directional jet leaves dead zones, particularly in corners. Biocidal efficacy remains limited to 3-4 log₁₀, insufficient for critical situations. Comparative studies show a spore inactivation rate of less than 15%, compared to over 95% for thermal vaporization. Droplets larger than 10 μm settle rapidly, reducing exposure in distant areas.
The rotating disc is suitable for moderate applications: small laboratory spaces, mobile booths, emergency situations, and contexts without strict NAS criteria. Its usefulness remains limited to situations where cost takes precedence over biocidal efficacy.
Venturi Nebulization
The Venturi effect creates a low-pressure area that draws hydrogen peroxide (5-12% concentration) into a stream of compressed air (2-10 bar). The typical suction ratio reaches 0.25-0.35: for every 100 L/h of engine air, 25-35 L/h of solution are drawn in. The mixture passes through a turbulent chamber and then a restrictive nozzle, fragmenting the liquid into aerosols through a series of aerodynamic stages. The log-normal particle size distribution has a median aerodynamic diameter of 4-6 μm, allowing for prolonged suspension.
The Venturi system is designed for hospital environments (operating rooms, intensive care units), microbiology laboratories, decontamination of sensitive equipment (electronics, optical instruments), and respirator reconditioning. Its moderate acquisition cost, lack of complex heating requirements, increased safety through reduced concentrations, and portability promote adoption. Limitations include sensitivity to air pressure (critical fluctuation of ±0.5 bar), nozzle wear, slightly asymmetrical distribution, and the absence of EN 17272 standardization specific to plasma-activated systems (development underway). Dependence on normal ambient temperature (15-30°C) means reduced performance in extreme environments.
Ultrasonic Vibration Nebulization
A fourth innovative approach relies on ultrasonic vibration. A ceramic transducer vibrating at a controlled frequency (0.8 MHz, 1.6 MHz, or 2.4 MHz) fragments the H₂O₂ solution into microdroplets whose size depends precisely on the frequency. At 0.8 MHz, the particle size distribution peaks at around 5 μm, at 1.6 MHz at approximately 3 μm, and at 2.4 MHz at approximately 1 μm. The experimentally discovered geometric optimum is 3 μm, combining the absence of condensation, efficient air transport (> 10 m), and zero risk of corrosion.
The fundamental mechanism distinguishes this approach: ultrafine particles (< 5 μm) possess a near-zero impact energy according to E = ½mv² (mass m → 0). They float in the air without sufficient force to corrode surfaces. Gradually, they vaporize, releasing oxygen radicals (O₂⁻) that destroy cell membranes through oxidation. This technology operates effectively with a reduced H₂O₂ concentration (7.5%), minimizing inhalation risks and safety requirements.
The separation of ultrafine particles from heavier droplets is achieved through Bernoulli pressure separation: the flow of compressed air generates a pressure difference that isolates the lighter particles. The major technical challenge concerns the corrosion resistance of the ultrasonic transducer (ceramic material), which is addressed by developing antioxidant barriers. The generation of droplets without direct splashing is circumvented by Bernoulli pressure separation, which ejects only the ultrafine particles.
Synthetic Comparison
Technological selection follows a simple decision hierarchy: for 10⁻⁶ sterility assurance (aseptic pharma), VHP is often chosen, but devices such as the rotating disc or ultrasonic vibration are now being studied, particularly for small volumes.
For 4-6 log reduction (hospital, standard lab) of larger volumes, the Venturi becomes an interesting economic choice.
Validation and Security
The EN 17272:2020 standard establishes the single European validation framework for all systems. Field trials or validations can be performed using biological indicators containing 10⁶ Geobacillus stearothermophilus spores with a post-cycle incubation of 5–7 days at 56°C. The success criterion requires ≥ 90% of the indicators to be inactivated at each position, demonstrating a reliable 6-log reduction. However, other strains may be used depending on the objectives and constraints of the specific sites.
Exposure limits for gaseous hydrogen peroxide are set at 1 ppm by OSHA/ACGIH (8 hours). During ventilation, a minimum of 20 air changes per minute (ACH) reduces the concentration.
Equipment selection criteria
Choosing the right air disinfection equipment for a laboratory requires consideration of several criteria:
Efficiency
The effectiveness of the equipment must be proven through studies and tests. Look for recognized certifications and standards.
Cost
The initial purchase cost represents only part of the calculation. Long-term maintenance and operating costs must also be taken into account.
Ease of use
The equipment must be easy to install and use. Minimal training must be required for staff.
environmental impact
Opt for technologies that minimize environmental impact, such as those that do not use harmful chemicals.
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