UV in professional kitchens

UV-C in Professional Kitchens - Grease Elimination and Odor Control


Keeping the kitchen hood and exhaust system ducts clean and hygienic is crucial in restaurants, large kitchens, community kitchens, shopping malls, office buildings, hotels, and food courts. Proper hygiene prevents (and eliminates) devastating problems caused by inefficient ventilation systems while reducing the risk of fires. Besides this, the challenges associated with reducing the odors produced by cooking food are widespread and represent an increasing issue in all restaurants.


The type and quantity of pollutants emitted depend mainly on the cooked product, the cooking methods, and the means used. The substances responsible for cooking odors are fatty acids, aliphatic and aromatic hydrocarbons, aromatic amines, and aldehydes. There are many ways to filter odors, but there are no specific rules for “olfactory pollution.”
Odor is a complex phenomenon to understand, not just for the wide range of potentially odorous substances, but mainly because the ability of a sense to be perceived by our olfactory system depends on different aspects that are both objective (volatility, water solubility, etc.) and subjective (physiological and psychological of the observer) but can also involve the environment (temperature, pressure, relative humidity of the air, speed and direction of the winds). This means that the same substance, at a distance from the source, is perceived differently by different people.
Organic compounds can constitute a vital friction point between the restaurant/hotel/catering and the surrounding environment since smells can spread over large areas. Without that, anybody can carry out resolutive interventions to contain it, avoiding the exasperation of the people involved.


According to the National Fire Protection Association (NFPA) in the USA, most restaurant fires originate on kitchen cooking appliances, flare into the kitchen exhaust system laden with grease, and then onto the building roof. Fat pollutants are also generated during food cooking, and grease layers will form inside the kitchen hood and the exhaust system ducts. So besides the inconveniences caused by unpleasant smells, fat deposits can pose a risk of fire risks. To prevent the formation of grease in the exhaust system ducts, continuous maintenance operations are necessary.
UV-C lamps are unique lamps whose light emissions can break the bonds of fat compounds by “breaking” them down into simpler molecules already present in the air (such as H2O, CO2, etc.). This is scientifically called “cold combustion.”
So UV-C technology is the most effective way to reduce grease deposition on the ductwork and pollution in the exhaust system ducts. The advantages of using this technology extend far beyond their effectiveness and, among other things, allow you to:

  • REDUCE COSTS for the maintenance of the kitchen hood and the exhaust system ducts
  • ENSURING SAFETY in the cooking area
  • ENSURING CLEANING and hygiene of the cooking area


Suppose it is challenging to test the effectiveness of reducing odors since they are perceived differently from person to person. In that case, it is, however, possible to carry out tests to verify the effectiveness of UV-C technology in reducing the formation of grease inside kitchen hoods and smoke evacuation systems. Light Progress Srl designed and manufactured a “UV-SMELL” section in Italy as part of our study. We ran an internal test on 12 different UV-C applications in professional kitchens. The test shows that in each of the 12 applications, the grease concentration inside the hood is significantly reduced if a UV-C section is placed inside the hood. The “UV-SMELL” systems can be installed in hoods that treat from 1,000 mc / h up to 4,800 mc / h of exhausted air and are, therefore, a flexible solution for various systems, both newly installed and existing.


The ideal ventilation system in a large professional kitchen should include a portion containing UV-C lamps, possibly with lights with Ozone emissions and filtration systems in Titanium Dioxide (TiO2) and Silver Salts to achieve higher efficiency. The first combination is with TIOX® honeycomb filters, an original Light Progress filter coated with nano-structured Titanium Dioxide (TiO2) and Silver Salts that, in combination with the very high UV-C power emitted by lamps, is an excellent photo-catalyst that degrades pollutants and organic and inorganic compounds (SOV, NOx, and VOC volatile organic compounds, nitrogen oxides). Consequently, the TIOX® filter performs further oxidation of polluting particles and contributes significantly to the deodorizing action of UV-C. Installation is straightforward and safe; the only precaution is to mount it downstream of mechanical filters that micronize fat molecules like standard mesh or labyrinth filters. A second option for maintaining cleanliness and eliminating odors is to use UV-C lamps that emit ozone. An oxidation reaction is triggered as soon as ozone comes into contact with molecules, which are oxidized and transformed into harmless molecules, thus eliminating any form of foul smell. Some lamps can be made with special transparent quartz at a wavelength of 180 nanometers, which can “transform” oxygen molecules into Ozone (O3).

The application in the kitchens’ ventilation channels effectively eliminates odors precisely because ozone can “follow” the smells along the ductwork, eliminating them before they are released outside. The properties of ozone are both ultra clean and persistent over time; ozone is, in fact, a volatile molecule that tends to re-transform into oxygen soon. Finally, applying UV-C technology, stand-alone or combined with Ozone emissions and Titanium Dioxide filters, perfectly combines with activated carbon filters. These technologies fight odors effectively together, and carbon filters are vastly improved by applying ultraviolet rays, increasing their durability and efficiency.


Installation of the technologies mentioned above is widespread in professional kitchens. Despite certain best practices and recommendations, their technologies are safe and easy to install. Installing UV systems right after the hood keeps surfaces clean from the start, and the air “free” of fat compounds leaves no residue in the ventilation duct. The optimum airspeed must not exceed 2.5 m / s. In the hood, UV systems must be positioned so that filters shield the rays from the operator and provide an easy way to turn them off. Using ozone, it is always advisable to add a pressure switch that automatically switches off the UV system in the event of a stop in ventilation. This is to guarantee operators’ safety.

In the case of outlets at street level and the application of UV + Ozone systems, it is essential to ensure that the ozone has completely “turned back” into oxygen before the air comes out into the street. Usually, a few meters of channel are required for this to happen. Otherwise, applying a second UV-ONLY system at the outlet can guarantee its complete elimination; UV-C rays “help” the O3 molecules turn into O2.


Ultraviolet rays are electromagnetic waves that are part of the electromagnetic spectrum. Electromagnetic waves are divided into three main wavelength bands, expressed in nanometers, nm: Ultraviolet rays (UV) 100-400 nm Visible rays (light) 400-700 nm Infrared rays (IR) 700-800,000 nm UV rays are in turn, identified in three bands:

  • UV-A (315-400 nm) with tanning properties;
  • UV-B (280-315 nm) con proprietà terapeutiche e di sintesi della vitamina “D”;
  • UV-C (100-280 nm) with germicidal properties.

UV rays are eco-friendly. Bacteria, viruses, spores, fungi, molds, and mites are all sensitive to UV-C rays and can be eliminated by them. Microbes cannot acquire resistance to UV-C rays, which only occurs using chemical disinfectants and antibiotics. When using ordinary disinfectants, environmental pollution is inevitable.

They also carry severe risks from the direct inhalation of vapors or the ingestion of foods contaminated after coming into direct contact with chemical disinfectants. Where the use of chemical disinfectants is unavoidable (food/pharmaceutical/healthcare industries, etc.), using ultraviolet rays in the disinfection process can reduce the amount needed, which allows for significant cost savings and is better for the environment while maintaining – and most of the time, improving – disinfection quality.

UV-C ray devices can be installed in most environments and machinery.

They can be programmed to maintain the same level of disinfection day and night, ensuring ideal hygiene conditions without any fluctuation in quality. In contrast, chemical disinfectants are most effective at the time of use.

LIGHT PROGRESS UV-C-equipped devices offer low running costs and are maintenance-free, besides standard bulb replacement. These robust and highly durable systems provide exceptional value for money. For this reason, eliminating germs using UV-C as opposed to (or together with) other systems offers excellent results at a low cost.

UV-C rays (100-280 nm) have a robust germicidal effect and reach their maximum efficacy at the 265 nm wavelength. The germicidal effect of UV-C radiation covers bacteria, viruses, spores, fungi, molds, and mites; this is mainly due to the destructive impact of the UV-C rays on their DNA, which damages their reproductive system and prevents them from replicating.

These lamps have an emission of around 90% over the 253.7 nm wavelength. This frequency is invisible to the human eye and has solid germicidal power. The remaining 10% of the lamp’s emission is visible (typically appearing as a blueish light).

Yes, UV-C rays are found in nature as they are generated by the sun, but the ozone layer in the atmosphere acts as a shield that stops them from reaching the earth’s surface.

Legal limits for microbiological contamination of drinking water are very stringent under Legislative Decree 31/2011. Water can be treated chemically by chlorination or physically by UV-C rays and heat to eliminate microorganisms. Initially, ingested water may contain dangerous residual contaminants derived from chlorine, such as chloramines, which alter the taste and smell of water, or by-products harmful to human health and the environment, such as inorganic substances, which contribute to trihalomethane, which is highly carcinogenic. It may be possible to avoid the problems mentioned above by heating the water before use, but it is not practical and would require long cooling times to solve.

By irradiating microorganisms with a much higher dose than the minimum safety dose, a UV-C ray device installed on the pipe near the point of use of the water can safely eliminate all microorganisms. Systems and spare parts (lamps) are very inexpensive to buy and maintain. When chlorine and derivatives are present, UV-C rays reduce them to elementary particles that are harmless to humans.

When you turn on a UV-C lamp you get a strong reduction in the microbes present in the ambient air and on the surfaces reached by the UV rays. The device reduces Bacillus, Coli, Clostridium, Legionella, Vibrio, Salmonella, Listeria, Pseudomonas, Staphylococcus, Streptococcus Bacteria by 99% in a matter of minutes if placed three meters from it. This feature also allows you to intervene in areas otherwise unreachable by solid bodies such as objects and cleaning and disinfectant products. Although chemical disinfectants are mandatory, irradiating surfaces avoids shaded areas, does not generate resistant species and can be used day or night (in the absence of people), preventing rapid recontamination of surfaces and ensuring that they are always in optimal microbiological condition.

UV-C rays are used every day, primarily in:

Food and pharmaceutical industries disinfect the air and surfaces of production environments and disinfect product containers (packaging), to isolate “protected” areas for the production and packaging of products, such as clean rooms, from areas at risk of contamination. These actions significantly increase the safety and shelf life of the products we buy, with numerous benefits to our health given that they do not leave any residue and allow the elimination or reduction of chemical disinfectants, which on the contrary, may leave hazardous residue on the products.

Hospitals, to avoid the transmission, and therefore contagion of dangerous bacteria or viruses that may be found in their air or transmitted by contact between the sick and visitors.

Water treatment systems provide drinking water for humans and animals and for healthcare use to eliminate all microorganisms that might be found in water from wells, tanks, and aqueducts. This system is mandatory downstream of a carbon-activated filter, for example, in water dispensers, which are becoming increasingly popular in cities.

There are no limits to the possible applications of UV-C light; even in domestic environments, it is used to prevent mold formation on walls, eliminate mites from the bedroom, keep the indoor air healthy, and treat water.

UV-C light can also eliminate odors and grease deposits in industrial kitchens and restaurants, assisted by ozone emission. Light Progress has developed a specific system also for this type of application.

Bacteria, viruses, spores, fungi, molds, and mites are all sensitive to and eliminated by UV-C radiation.

Each bacterium, virus, yeast, mold, or mite requires a different UV-C dose to be deactivated or eliminated. There are widely recognized documents that report these levels. Light Progress has one of these documents and uses it regularly in designing and implementing its systems. To give an approximate idea regarding the application times of UV-C rays, these can range from fractions of a second to several seconds.

Viruses, bacteria, mold, animal waste, mites, and pollen are among the leading causes of dangerous infections and allergies. Each contaminant is dispersed differently: mites, spores, bacteria, and mold, for example, are continuously transported by air, while other bacteria and viruses are “grouped” into solid particles, such as spores or drops of moisture, and then inhaled by humans.

In air conditioning systems, when contaminants get inside the air treatment unit (ATU) and air distribution ducts, the design, which is dark and moist, becomes a breeding ground for them to grow and multiply, making the air we breathe unsafe.

The air also contains concentrations of dangerous chemical pollutants if inhaled in large quantities or continuously. Irradiating air in a central system or installing an air purifier complete with UV-C lamps and a TiOx titanium dioxide filter dramatically reduces the likelihood that these pollutants (whether microbiological or physicochemical) will result in health problems that often can only be diagnosed after many years.

The efficacy of disinfection systems can easily be ascertained through microbiological analyses or simple swab tests used to identify the presence of microorganisms on the tested surfaces. To verify the same microbial load on surfaces, in the air, and in water, before and after the treatment, it is necessary to carry out lab tests such as those for HACCP. For chemical disinfectants, producers need to provide tests declaring their disinfectant capacity; Light Progress has similarly carried out necessary tests in university labs and at private accredited bodies. Of course, for chemical disinfectants and UVGI technology to obtain the same laboratory results, the products must comply with the instructions for use.

UV-C rays cannot penetrate solid bodies, unlike ionizing radiation such as x-rays and gamma rays, which are highly dangerous to humans, even at low doses. To eliminate microorganisms using UV-C rays, they must be present on the surface of an object or transported by the air.


Significantly few materials will not block the passage of the germicidal wavelength (253.7 nm, invisible), including quartz and certain plastics such as PE or tetrafluoro-derivatives, but only if these are just a few microbes thick.

Regular window glass, polycarbonate, and other transparent materials through which it is possible to see the bluish light of UV-C lights completely nullify their germicidal effect, acting as a screen.


Continuous irradiation of the eyes and skin could cause erythema and conjunctivitis, which generally clear up in a few hours. In any case, it is sensible to avoid direct, close-up exposure to sources of UV-C rays, even for short periods. To prevent direct exposure, cover the area to be protected using any material that is not transparent to visible light (cotton or woolen clothing or overalls) or glass or transparent plastics (masks, helmets, glasses, etc.).


Yes. Light Progress offers two solutions in a unique plastic material: Uvlon Frame and Uvlon Pipe. Uvlon Frame is made from a film attached to the device and collects fragments from breakage. Uvlon Pipe is a casing thermally applied to the UV-C tube in the factory, which increases its mechanical strength (car windscreen effect) and collects and retains any broken fragments inside.


UV-C rays are similar to solar rays but do not transmit heat. However, like solar rays, they tend to have a yellowing effect on plastics exposed for extended periods (mainly white plastics).

Bacteria, Viruses, Spores, Fungi, Mold, and Mites are all sensitive to, and can therefore be eliminated with, UV-C light. Microbes cannot acquire resistance to UV-C light, unlike that which occurs using chemical disinfectants and antibiotics. UV rays are ecological. Polluting the environment is inevitable using normal disinfectants. Directly inhaling the vapors, or swallowing food products contaminated by any contact with said chemical disinfectants, can also give rise to a number of serious risks. In cases where chemical disinfectants cannot be eliminated (food, pharmaceutical, healthcare industries, etc.), using ultraviolet rays for disinfection allows a reduction in their use, with considerable economic savings and greater care for the environment, while maintaining and almost always improving the level of disinfection. UV-C light devices can be installed in environments and on machinery and be programmed to maintain the same level of disinfection day and night, guaranteeing ideal hygiene conditions, without highs and lows. On the contrary, chemical disinfectants are effective only during their actual use. Using LIGHT PROGRESS equipped luminaires, operating costs are negligible; it could be said that “LIGHT PROGRESS” UV-C systems do not require maintenance except for the normal replacement of the lamps. The cost/benefit ratio is considered excellent; the devices are both powerful and long-lasting. Hence the elimination of germs using UV-C technology is low-cost and highly effective compared to (or in combination with) other systems.

UV-C light genuinely works if properly applied and with the necessary precautions. The difference between a quality project, and an application that fails to bring the desired results, lies in the degree of knowledge about the subject, and level of experience acquired over time. Light Progress has been developing successful projects worldwide since 1987, and has built a client portfolio consisting of important companies in all fields requiring certified hygienic conditions to produce quality products and services.