A typical scenario (an illustrative situation based on common post-flood problems, not a review from any specific customer)

The morning parents started asking "When do you reopen?" and the nap room still smelled musty

Teacher Ann runs a small private nursery in a three-storey townhouse she converted into a childcare centre, down a soi in the Khlong Chan area of eastern Bangkok. She looks after about twenty children aged from eighteen months to four years. The ground floor is a bright activity room laid with interlocking foam mats, a doll-house corner, a low bookshelf full of picture books and a children's bathroom with small toilets. The second floor is the nap room, where thin sleeping mats are laid out in neat rows every afternoon.

Between 24 and 27 September 2026, continuous heavy rain flooded large parts of eastern Bangkok. According to news reports, the Bangkok Metropolitan Administration declared all 50 districts a disaster zone on 26 September. Ann closed the centre on the first day water started creeping into the soi. Brown, murky water entered the ground-floor activity room to about mid-shin height and stayed for several days, because the surrounding canals were full and, as the governor explained, drainage would take two to three days after the rain stopped.

When the water finally receded, Ann and her three assistants shovelled out the mud, scrubbed the floor and threw away box after box of soaked soft toys. Yet what worried her most was not the mud she could see. It was the faint, damp, musty smell drifting up into the second-floor nap room, the small black spots appearing along the bottom edge of the bare plaster wall, and the same question arriving in the parents' LINE group every day: "Teacher, when will the centre reopen? Is it safe for my child yet?"

Ann knows that children this age crawl on the floor, put toys in their mouths, roll around on mats and touch everything at eye level. If the centre reopens too soon while germs and mold spores are still lingering, one sick child can pass an illness to the whole room within days, and the trust she has built over years could disappear in a single week. This guide is written for nursery owners, private daycare operators and early-childhood centres across Bangkok who are facing exactly the same question.

Why childcare centres need extra care after a flood

Urban floodwater is not clean rainwater. On its way through streets, drains, canals and septic tanks it picks up sewage, animal urine, rubbish and fuel. Once inside a building, those contaminants settle into the mud, soak into porous materials and leave moisture trapped in walls and floors for weeks.

In an ordinary home that risk is shared by a few people. In a nursery, many young children share the same floor, the same toys and the same air for several hours a day. Children under five have immune systems that are still developing, they breathe faster than adults and therefore take in more air relative to their body weight, and they put their hands in their mouths constantly. That is why a childcare setting needs a higher standard of cleanliness than a typical home once the water has gone.

Germs worth knowing about in early-years spaces

• Mold. Black, green or grey mold grows on walls, under foam mats, behind plywood cabinets and inside sleeping mats. Its spores become airborne easily and can trigger allergy symptoms such as sneezing, a blocked nose and itchy rashes, and can make asthma worse in children who already have it.
• Bacteria from sewage. E. coli and other bacteria that cause diarrhoea travel in with mud and wastewater. A toddler who crawls across the floor and then sucks a thumb is exposed to a gut infection.
• Viruses that spread quickly among children. These include the viruses behind hand-foot-and-mouth disease, rotavirus and norovirus, which cause vomiting and diarrhoea, and respiratory viruses such as RSV, which often circulate in the rainy season. When children gather again after a flood closure, transmission through shared surfaces and toys can be fast.
• Leptospirosis. Children may never have waded through floodwater, but teachers and helpers who did the clean-up can be exposed through cuts on their hands or feet. Anyone who develops a high fever or calf pain after wading must see a doctor straight away.

Symptoms teachers and parents should watch for

After reopening, watch for fever, coughing, a persistently runny nose, wheezing, red spots or blisters on the hands, feet or inside the mouth, repeated loose stools, vomiting, unusual drowsiness, refusing food, or itchy skin rashes. A child with any of these should stay home and see a doctor. Centres should run a clear morning health check at the door. Ozone treatment reduces germs in the environment; it is not a treatment for illness and never replaces medical advice.

Who is most at risk inside the centre

Babies and toddlers under two who still crawl and explore with their mouths, children with a history of asthma, allergies or eczema, children who have just recovered from an illness, pregnant teachers and older helpers who spend the whole day inside. These groups deserve special thought when you choose a reopening date.

What nursery owners risk if post-flood cleaning falls short

Children's and staff health

Once one child develops diarrhoea or mouth blisters, illness can move through a classroom in days. Teachers who change nappies, feed children and carry them are likely to fall ill too, which cuts staffing just as the centre reopens. Children who react to mold may develop a lingering cough and congestion without parents realising that the real cause is a nap room that is still damp.

Money

Most private nurseries depend on monthly fees. Staying closed too long means lost income, but reopening too early and then having to close again because of an outbreak can cost even more: a second round of cleaning, new toys and mats, and wages for helpers who must still be paid when no children attend.

Time and operations

Every day of delay is a day when parents must take leave or find emergency childcare. Some families may move their child to another centre permanently.

Reputation and trust

Childcare runs on trust. One parent posting "my child came home from nursery with diarrhoea" can make others hesitate immediately. On the other hand, a centre that explains clearly that it completed every cleaning step, with photos and a written list, wins confidence back much faster.

Why familiar quick fixes are not enough

Mopping with bleach alone. Bleach can disinfect smooth surfaces that you actually wipe, but it does not reach under interlocking foam mats, into wall joints, behind cabinets, inside air-conditioning units or into the air. Strong chlorine fumes can also irritate small children's airways, and mixing bleach with some toilet cleaners can release dangerous gas.

Running fans and calling it dry. A fan makes surfaces look dry, but moisture stays inside plaster, plywood and the foam of sleeping mats, and the moving air spreads mold spores around the room.

Air fresheners and essential-oil diffusers. A pleasant scent covers the musty smell for a while, but it does nothing to reduce germs, and some fragrances trigger allergy symptoms in sensitive children.

Painting over mold stains. Living mold under fresh paint returns as blotches within weeks, and new paint adds chemical odours to the room where children will nap.

Washing only some toys and fabrics. Large toys, the doll house, bookshelves, curtains and sleeping mats are often given a quick wipe because they are hard to move, yet they are exactly what children touch most.

All of these approaches share one weakness: they deal only with what you can see and reach. Many germs sit in the air, in corners and on surfaces nobody thinks about. That is the gap ozone helps close, after the basic cleaning has been completed.

WHD ozone disinfection: the finishing step before children come back

World Health Disinfection (WHD) provides residential and building ozone disinfection in Bangkok and the surrounding provinces, covering homes, condominiums, offices, schools, hotels and shared spaces used by many people, including nurseries and daycare centres.

How ozone works

Ozone (O3) is oxygen with three atoms and a strong oxidising effect. Released at a controlled concentration inside a closed room, it spreads into every corner that air can reach: under small tables, behind bookshelves, inside air-conditioner vents and over the surfaces of toys left in the room. Ozone breaks down the cell structures of viruses, bacteria and mold, and also odour molecules, then reverts to oxygen (O2). It leaves no chemical residue on the lunch tables or toys that children will later put in their mouths.

According to test results certified for the company, WHD's service has been tested by Thailand's Department of Medical Sciences and by Intertek (UK), eliminating viruses, bacteria and mold by 99.99%. Details are on the service page.

Non-negotiable safety rules

Ozone treatment is done only in an empty, closed space. Children, teachers, helpers, pets, fish tanks and plants must all be out of the area during treatment, and people return only after the rest and ventilation period the team specifies. High concentrations of ozone irritate the airways, so nobody should be inside while the generator is running. For a nursery, we recommend scheduling treatment on a day when the centre is still closed and leaving plenty of airing time before staff come in to set up.

Ozone comes after cleaning and drying. It does not replace shovelling out mud, washing and drying. If thick mud or organic residue remains, ozone is consumed by that dirt first and results are weaker.

How the work runs in a childcare centre

1. Survey and zoning. The team walks through the activity room, nap room, children's bathroom, food preparation area, toy store and staff room, checks moisture levels and mold stains, and sets the treatment order.
2. Preparation. Drawers, cupboards and toy boxes are opened so air can circulate, sleeping mats are stood up or spread out, windows and vents are closed, air-conditioning is switched off and the zone is confirmed empty of people and animals.
3. Ozone release. The generator fills the room to the level set for its size.
4. Contact time. Ozone works on surfaces and air for the appropriate period; a typical cycle takes about 30 minutes per zone.
5. Rest and ventilation. The machine is switched off, ozone is allowed to break down, then windows are opened before anyone is allowed back in.
6. Handover and advice. The team explains what to do afterwards: keeping the space dry, daily cleaning routines and moisture hot spots to watch.

Current promotion: ozone jobs worth 15,000 baht or more receive a free medical-grade disinfectant spray, which staff can use on high-touch surfaces in daily routines according to the label.

10 reasons nurseries and daycare centres should use ozone before reopening after a flood

1. It reaches places hands cannot. Under foam mats, behind cabinets, inside air-conditioners and in ceiling corners where mold spores hide.
2. No residue on toys. Ozone turns back into oxygen, which suits a space where children put things in their mouths.
3. It treats the air in nap rooms. A room where children breathe together for hours each day deserves more than a surface wipe.
4. It tackles musty odour at the source. Ozone breaks odour molecules down instead of covering them with fragrance that might trigger allergies.
5. Backed by testing. According to company-certified results from the Department of Medical Sciences and Intertek (UK). See the service details
6. Short time per zone. About 30 minutes per zone, so it can be planned for a single day before reopening.
7. It helps you communicate with parents. You can show a complete sequence: wash, dry, disinfect surfaces, then ozone. That clarity rebuilds confidence.
8. It lowers the chance of a new outbreak. Reducing germs in the environment before children regroup lowers the chance of illness spreading via surfaces.
9. It works well alongside disinfectant. Use a medical-grade disinfectant on high-touch surfaces and ozone for the air and hidden corners. Plan the job with WHD
10. Scheduled around your centre. The team plans dates, room sizes and zone order so teachers can set up on time. Request a quote

Before and after: what teachers and parents notice

Example case: a three-storey nursery planning to reopen within a week

Example case (an illustrative scenario explaining the order of work, not a real customer review)

Back to Teacher Ann in Khlong Chan. After the water went down she split the work into three phases. In the first two days the team shovelled out mud, carried every foam mat outside to wash with clean water and detergent, and stood the mats upright in the sun so their undersides could dry. Soaked soft toys and pillows went in the bin, as did swollen paper picture books, and the plywood shelving that had bloated was removed.

The second phase was drying. Ann opened every door and window during the day, used fans together with a borrowed dehumidifier to dry the walls, and had an electrician check the ground-floor sockets before power was switched back on. Lower wall sections with mold stains were scrubbed and left to dry completely rather than painted over straight away.

The third phase was disinfection. Ann wiped lunch tables, children's chairs, the small toilets, hand basins and the washed plastic toys with disinfectant, then booked the WHD team for ozone treatment on a day when the centre was still closed. The building was split into four zones: the ground-floor activity room, the children's bathroom and kitchen, the second-floor nap room, and the toy store with the staff room. Nobody was in the building during treatment; the classroom fish tank went to a neighbour's house and potted plants were carried out to the front.

After the rest and ventilation period, Ann noticed a clear reduction in the musty smell in the nap room. The next day the teachers put the room back together, laid the mats, and shared photos of every step in the parents' group along with a list of what had been thrown out and replaced. Many parents replied that they understood and were ready to bring their children back. During the first week the centre kept checking every child at the door each morning and ran the dehumidifier in the nap room whenever the children were not there.

Ann's lesson: parents' confidence does not come from the words "it's clean now". It comes from a sequence of steps that can be explained and checked.

Recovery checklist for childcare centres after the 2026 Bangkok floods

Safety first

• Cut power to flooded floors and have an electrician inspect the system before use. Never touch switches with wet hands or while standing on a wet floor.
• Cleaners wear rubber gloves, boots and masks, and cover any cuts completely.
• Keep children away from the building during every stage of cleaning.

What to throw away

• Soft toys, pillows, blankets and foam mats soaked in dirty water that cannot be cleaned through
• Paper picture books, flash cards and teaching materials that have swollen
• Plywood or particle-board furniture that has bloated
• Food, formula and feeding bottles that touched floodwater

What can be washed and disinfected

• Hard plastic toys: wash with soapy water, rinse, disinfect per the label, air-dry
• Interlocking foam mats: wash both sides and stand upright until completely dry
• Children's tables, chairs and plastic or metal shelving
• Children's toilets, hand basins and bathroom floors

Before ozone day

• Finish mud removal and washing, and dry the space as much as possible. Public-health bodies such as the CDC and WHO advise cleaning and drying quickly, within 24 to 48 hours where possible, to limit mold growth.
• Open cupboards, drawers and toy boxes, and stand sleeping mats up so air can reach them.
• Move pets, fish tanks and plants out of the building.
• Remove important documents and non-essential electronics, or tell the team in advance.

After ozone, before children return

• Enter only after the team confirms the rest and ventilation period is over.
• Open windows for extra airing, then do a final dust of surfaces.
• Clean the air-conditioner filters or book an air-conditioning service.
• Run a morning health check and ask parents to keep children with fever, diarrhoea or blisters at home.
• Keep watching for damp and new mold spots for at least a month.

For high-touch surfaces you can use the Chemgene HLD4H medical-grade disinfectant at the dilution and contact time on its label. If repairs involve repainting or new floor coatings that leave chemical smells, see the ozone chemical-residue and odour removal service.

FAQ: ozone disinfection in nurseries after a flood

1. Can children go back into the room straight after treatment?

No. Wait until the rest and ventilation period the team gives you has passed. For early-years centres we recommend treating on a closed day, letting teachers open windows and set up first, and welcoming children the following day.

2. Does ozone leave residue on toys?

Ozone breaks down into oxygen and leaves no chemical residue on surfaces. However, toys that were underwater still need washing with soapy water and normal disinfection first, because ozone does not wash away mud.

3. The walls are still damp. Can we treat now?

Dry as much as you can first. If moisture in the walls stays high, mold can regrow even after its numbers have been reduced. The team will help judge whether to wait or proceed in current conditions.

4. Our centre has several floors. How long will it take?

A typical cycle is about 30 minutes per zone, not including preparation and airing. The number of zones depends on room sizes and layout; you will receive a schedule after the survey.

5. Can ozone replace disinfectant?

They should not replace each other. Disinfectant suits high-touch surfaces that need wiping every day; ozone suits whole-room air and hidden corners after cleaning is complete.

6. What if a child becomes ill after reopening?

Separate the child from the group, ask the parents to take them to a doctor, and clean the surfaces they touched immediately. Ozone reduces germs in the environment; it is not a treatment and does not replace medical care.

7. Should we treat again later?

That depends on how much damp remains in the building. If new mold or mustiness appears, fix the moisture source first, then consider another treatment. Many centres choose to treat during term breaks as part of long-term care.

A note to every nursery owner in Bangkok

According to news reports, the late-September 2026 Bangkok floods followed roughly 300 mm of rain in about 48 hours, and Thai media compared the event with the great floods of 2011. Even where water has receded, some roads such as Si Burapha and Lat Phrao still had 20 to 40 cm of standing water on 30 September, so damp will stay in buildings across these neighbourhoods for weeks.

News reports also recorded lives lost in this disaster. We extend our condolences to every family affected, and we ask every centre to make electrical safety the first step before any recovery work.

A nursery is where parents leave the most precious thing in their lives. Choosing not to rush reopening until you have washed, dried, disinfected and treated the air is a responsible decision.

Get your nursery ready to welcome children back with confidence

Talk to WHD to survey your centre, set zones and plan ozone disinfection on a closed day, always in an empty room with no people or animals inside, with clear advice before children return.

See the Ozone Disinfection Service

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

Related pages

• Residential and building ozone disinfection
• Ozone odour and chemical-residue removal
• Chemgene HLD4H medical-grade disinfectant

References

• Wikipedia: 2026 Bangkok floods
• Al Jazeera: Disaster zone declared across Bangkok as heavy rain triggers flooding
• CDC: Floods and clean-up guidance
• WHO fact sheets