A Story From the Field: Hia Lek and the Freezer Door That Made Him Step Back

Hia Lek runs a second-generation business buying and freezing seafood in Phra Samut Chedi, Samut Prakan, close to the mouth of the Chao Phraya. His warehouse has one chill room for fresh catch, two freezer rooms, stainless-steel tables for sorting shrimp, squid and fish, an ice machine, and a wash bay with drainage channels. His customers are restaurants, market vendors and small exporters who expect clean, fresh product every single day.

At the end of September 2026, heavy rain combined with a high sea tide. Water came into the warehouse above ankle height and stayed for several days. The power had to be cut for safety, and the cold-room compressors stopped. Hia Lek managed to move some stock to a friend's cold store, but several tonnes of shrimp and squid were still thawing inside the freezer rooms.

When the power came back and the water went down, he opened the first freezer door and was driven back by an overpowering smell of rotting seafood. Meltwater from the thawed product had spread across the floor and mixed with mud that the flood had pushed in through the drainage channels. The rubber door gaskets were stained black, the corners of the insulated panels showed the first spots of mold, and the wash bay drains were pushing a foul smell back up. Several workers said they could not stay inside for more than ten minutes without feeling dizzy.

Regular customers kept calling to ask when deliveries would resume. Hia Lek knew that if he put fresh stock into a room that still smelled of rot and carried a load of bacteria, good product would pick up the odor and spoil faster. Two generations of trust could disappear in a single shipment. So he contacted World Health Disinfection (WHD) to restore the cold rooms properly.

Hia Lek's story is a composite drawn from situations our team encounters after floods. It is not a news report, but many coastal seafood businesses that faced flooding and power cuts at the same time will recognize it.

Why Cold Rooms Are Harder to Recover After Floods and Power Cuts Than People Expect

A cold room is designed to be airtight so it holds the cold. That also means that when something rots inside, the smell has nowhere to go. Proteins and fats from thawed and decomposing seafood seep into the joints between insulated panels, the door gaskets, floor grooves and shelving. Floodwater entering through the drainage channels adds mud and germs of its own.

Health and food-safety risks

• Bacteria from spoiled food and floodwater: Liquid from rotting seafood mixed with floodwater is a breeding ground for many kinds of bacteria. If residue remains on shelves or floors, new stock can be contaminated.
• Leptospirosis: Coastal areas and food warehouses attract rats. Workers washing the warehouse with cuts on their skin must wear boots and gloves.
• Decomposition gases: Seafood rotting in a sealed room can release strong-smelling gases that cause dizziness and nausea. Ventilate thoroughly before anyone goes in to work.
• Mold: As a cold room warms up and stays humid, mold grows along gaskets and panel joints and can return whenever humidity rises.

Business risks

The seafood trade competes on freshness and hygiene. Restaurant buyers and exporters smell product every time. If a new batch of shrimp or squid picks up a rotten odor from the room, the customer may reject the whole lot and move permanently to another supplier. On top of that there is the cost of spoiled stock, fees for external cold storage, and the time the business sits idle.

There is also a hidden cost in staff morale and safety. Workers who have to spend hours scrubbing a room that smells of rot are understandably reluctant, and a clean-up that drags on for weeks wears everyone down. A clear, professional plan gets the job done faster and safer.

What Owners Usually Try, and Why the Rotten Smell Stays

• Pressure-washing alone: It removes visible residue, but proteins and fats in panel joints remain, and water trapped in grooves adds to the humidity.
• Pouring strong bleach: The chlorine smell blends with the fishy odor and lingers in a sealed room, so new stock picks up a chemical taint.
• Coffee grounds or charcoal: These help a little in a small space but are not enough for a cold room with severe rot odor.
• Switching the refrigeration back on immediately: Cold makes the smell seem weaker for a while, but it does not remove it. The moment the door opens or the coils defrost, the odor returns.
• Painting or coating over the surfaces: If the source of odor and germs has not been dealt with, coating it simply hides the problem underneath.

The Solution: Chemgene HLD4H Disinfection and Cold-Room Ozone Treatment by WHD

A sealed cold room is an ideal space for our ozone treatment service. Ozone spreads throughout the room, reaching panel joints, gaskets and shelving, where it helps break down the molecules responsible for rotten-seafood odor and deals with mold spores. Our disinfection fogging service with Chemgene HLD4H, applied as a fine ULV mist, disinfects surfaces inside the cold rooms, on sorting tables, in the wash bay, along drainage channels and across the flooded warehouse floor.

Step by step for cold rooms and seafood warehouses

1. Survey: We inspect each cold room, the flood level, the areas with the strongest odor, drainage channels, door gaskets and any damage to the insulated panels.
2. Clearing and washing advice: Dispose of spoiled stock correctly, remove protein and fat residue with a food-grade degreaser, clear mud from the drains, take out removable shelving for washing and open the doors to ventilate.
3. Disinfection fogging: Chemgene HLD4H mist is applied inside the cold rooms, on shelving and door frames, sorting tables, the wash bay and around drains.
4. Ozone treatment: Each empty cold room is sealed and treated according to its size and the severity of the odor. No people, animals or food products may be inside during treatment.
5. Ventilation: Doors are opened and fans run until the ozone has broken down into oxygen, before workers enter and before refrigeration is switched back on.
6. Re-check: We check the odor again. A room with very severe odor may need a second round before it is cooled down and receives fresh stock.

10 Reasons Seafood Businesses in Phra Samut Chedi Choose WHD

1. Perfect for sealed rooms: Ozone treatment reaches panel joints that hands cannot.
2. Rotten odor tackled at the source: Not simply masked with another smell.
3. Wash bay and drains disinfected: Our disinfection service covers wet areas.
4. A high-standard disinfectant: We use Chemgene HLD4H.
5. No harsh chemical smell left behind: New stock does not pick up a chlorine taint.
6. Less downtime: Room-by-room planning gets you receiving stock sooner.
7. The whole warehouse covered: From cold rooms to sorting tables and staff rest areas.
8. Safe for equipment: Controlled ozone and covered control panels.
9. Less residue odor after scrubbing: Use ozone treatment for chemical residue.
10. Mosquito control around a coastal warehouse: Add our mosquito spraying service.

Before and After the Cold Room Recovery

A Customer's Voice

"We washed the room ourselves three times and the smell was still there. I thought we would have to rip out the panels. After the team fogged and ozone-treated the empty rooms, most of that heavy rotten smell was gone. We switched the refrigeration back on and took in a new batch of shrimp, and none of our customers complained about any odor."
- Hia Lek, seafood cold-storage business owner, Phra Samut Chedi (a composite scenario based on on-site situations)

Hia Lek's story is similar to that of fish landing piers, cold stores that rent space, seafood wholesalers and small processing plants across Samut Prakan and the coast, many of which faced flooding and power cuts at the same time.

Checklist Before Reopening Cold Rooms and Receiving New Stock

• Have an electrician and a refrigeration technician check wiring, compressors and evaporator fans that were exposed to water.
• Sort and dispose of all thawed stock or stock that touched floodwater in the correct way.
• Remove protein and fat residue with a food-grade degreaser, then rinse with clean water.
• Clean drainage channels, debris traps and wastewater sumps thoroughly.
• Inspect insulated panels and door gaskets; replace anything swollen, torn or deeply moldy.
• Book disinfection fogging and ozone treatment for the empty cold rooms.
• Ventilate well, then switch the refrigeration on and wait for the target temperature before loading stock.
• Wash and disinfect sorting tables, baskets, ice bins and workers' boots.
• Record cleaning and disinfection dates as evidence for customers.

Spots Often Forgotten in Seafood Warehouses

The ice machine and ice bins: Ice touches product directly. An ice machine that was flooded must be checked and its system cleaned by a technician. Throw away all old ice and wash and disinfect the storage bins before use.

Plastic baskets and crates: Baskets that sat in floodwater hold mud in their small grooves. Scrub them one by one, then disinfect before putting them back into service.

Staff rest rooms and toilets: Workers using dirty toilets and rest areas can carry germs back into the sorting area. Include these spaces in the disinfection plan.

Refrigerated delivery trucks: If a reefer truck was parked in the warehouse during the flood, its insulated box may also smell and need ozone treatment.

Packaging stores: Cardboard boxes and plastic bags exposed to damp may grow mold and give off odor. Discard anything wet and store new packaging on raised shelving.

Preparing for the Next Power Cut and Flood

Coastal cold-storage businesses benefit from a contingency plan for the flood season. Arrange backup cold storage in advance, keep a standby generator on high ground, fit non-return valves on drainage channels, and raise sockets and control panels above the highest water level you have seen.

Once the crisis has passed, check cold rooms periodically for returning odor and mold, especially during coil defrost cycles. If the smell starts to creep back, a follow-up ozone treatment while the room is empty keeps it clean. Family homes and worker housing that flooded can be restored with residential ozone disinfection as well.

Understanding Why Seafood Odor Is So Persistent

Anyone who has worked with seafood knows that its smell clings to everything. The reason is chemistry. As fish and shellfish break down, they release nitrogen and sulfur compounds that are pungent even at very low concentrations. In a warm, closed cold room with no power, these compounds build up quickly and soak into every porous or textured surface: the slightly rough finish of panel skins, silicone sealant along joints, rubber gaskets, plastic curtains at the door and any timber pallets left inside.

Washing removes the bulk of the residue, and that step is essential. But the smell molecules that have already settled into joints and gaskets are not easily reached by water and detergent. That is why owners often report that the room smells fine while it is wet and freshly washed, then smells bad again a day later when it dries out. Ozone treatment addresses that residual layer. Because it is a gas, it reaches the same places the odor reached, and it reacts with odor compounds so that they no longer smell.

The best results always come from the right order of work: first physical removal of rotten material and residue, then disinfection of surfaces, then ozone treatment of the sealed and empty room, and finally ventilation and a check before cooling down. Skipping the washing step and relying on ozone alone gives poor results, while washing without ozone often leaves a stubborn background odor behind.

Protecting Workers During the Clean-Up

Cleaning a cold room full of rotting seafood is unpleasant and can be hazardous if it is not planned. Before anyone goes in, open the doors and let the room ventilate for a good while, using fans to push air through. Never send a worker alone into a closed room that smells strongly of decomposition.

• Protective gear: Rubber boots, long waterproof gloves, aprons and eye protection. A suitable mask helps with the smell and with splashes.
• Short shifts: Rotate workers so nobody spends too long inside the worst rooms.
• Hand washing: Provide clean water and soap at the exit, and keep a first-aid kit nearby for cuts.
• Waste handling: Bag spoiled product securely and arrange removal quickly, so it does not attract rats and flies around the warehouse.
• Health watch: Anyone who develops a fever, muscle pain or other symptoms after working in floodwater should see a doctor and mention the flood exposure.

Once the worst residue is out and the room has been disinfected and ozone-treated, the working environment improves dramatically, and staff can move on to restocking with confidence.

Strip Curtains, Pallets, Shelving and Evaporators

Several fittings inside a cold room deserve individual attention, because each can hold onto odor long after the walls and floor are clean.

PVC strip curtains: The overlapping plastic strips at the door are touched by every trolley and every worker. They trap slime and odor between the strips. Take them down, scrub each strip on both sides, rinse and disinfect, or simply replace them if they are stained or brittle. New strip curtains are inexpensive compared with the risk of tainting stock.

Timber pallets: Wooden pallets that sat in meltwater and floodwater absorb odor deep into the grain and are very hard to clean. In most cases they should be discarded and replaced with plastic pallets, which can be washed and disinfected properly.

Shelving and racking: Stainless-steel or coated racking can be restored by removing the shelves, scrubbing joints and brackets where residue collects, and including the frames in the fogging. Pay attention to the feet of the racks, where floodwater and meltwater pooled the longest.

Evaporator coils and drain pans: The cooling unit inside the room circulates air through its coils. If residue or mold has settled there, it will spread odor every time the fans run. Ask your refrigeration technician to clean the coils and drain pan and to check that the condensate line flows freely before the room is cooled down again.

Dealing with these fittings before the ozone treatment means the gas only has to tackle the residual odor in the structure, which gives a cleaner and longer-lasting result.

Rebuilding Customer Confidence

Seafood buyers talk to one another, and news of a flooded cold store spreads quickly along the coast. A short, honest update can reassure customers before they start looking elsewhere. Explain that spoiled stock was disposed of, the rooms were washed, disinfected and ozone-treated, gaskets were replaced where needed and the refrigeration was checked by a technician. Offer to let key buyers visit or inspect the first batch from the restored rooms.

A written record of the cleaning and disinfection dates is also useful for customers who supply restaurants or exporters, because it lets them answer their own customers' questions with confidence.

Frequently Asked Questions

Q: Can a cold room be ozone-treated while stock is still inside?
A: For post-flood restoration, treat only empty rooms. Remove all stock first, then ventilate thoroughly before loading fresh product.

Q: The rotten smell is very strong. Is one treatment enough?
A: It depends on the odor level and how well residue was removed beforehand. Rooms with very severe odor may need more than one round; our team will assess this at the re-check.

Q: Do we need to rip out the insulated panels?
A: Not in every case. Panels that are sound and have no water inside can usually be restored. Panels that are swollen or holding water internally should be assessed by a specialist for replacement.

Q: How long does the work take?
A: It depends on the number and size of rooms. We plan room by room so that finished rooms can be used first.

Q: How much does it cost?
A: It depends on the area, the number of rooms and the level of damage. Contact us for an assessment and quotation at 065-556-6294 or LINE @whd268.

Q: Do you serve areas near Phra Samut Chedi?
A: Yes. We serve Phra Samut Chedi, Mueang Samut Prakan, Phra Pradaeng, Bang Phli, Bang Bo and other areas across Bangkok and nearby provinces.

Clean Cold Rooms With No Rotten Odor, Ready for Fresh Stock

Cold rooms, freezer rooms, fish landing piers and seafood businesses in Phra Samut Chedi can book a survey with the WHD team today.

Book Ozone Treatment - Click Here

See Our Disinfection Service - Click Here

Call 065-556-6294 · LINE @whd268 · Email worldhealthdisinfection@gmail.com

Related Links

• Ozone treatment for odors and chemical residue
• Master Ozone Generator
• Chemgene HLD4H disinfectant
• All articles

Health reference: World Health Organization (WHO): Floods · Department of Health, Thailand