A typical scenario (an illustrative example drawn from common situations, not a review from any specific customer)

"The new kitchen is beautiful, but Phum wakes up coughing at 3 a.m."

Fon lives in a two-storey townhouse in Khlong Chan with her husband and their nine-year-old son Phum, who has had asthma since kindergarten. The family knows asthma care well: an inhaler always in his bag, an action plan from the doctor, no furry pets, sheets washed every week and an air purifier running in the bedroom all night. Fon's husband has allergic rhinitis and sneezes in bursts every morning. This household pays more attention to air quality than most.

In late September 2026, days of heavy rain flooded the ground floor almost to knee height. The kitchen, living room and storeroom sat under water for several days. When it drained, the plywood kitchen cabinets had swollen, the walls carried water stains and grey mold spots appeared in the corner behind the fridge. Fon sent Phum to his grandmother's during the clean-up, knowing that dust and mold are his worst enemies.

Once the house was washed and dried, the family hired a carpenter for new kitchen cabinets, repainted the ground-floor walls, sanded and lacquered the wooden stairs and laid new vinyl tiles with adhesive. The work took ten days. Everything looked clean and tidy, so Fon brought Phum home.

On the first night he had a dry cough at 3 a.m. On the second he coughed harder and needed his reliever inhaler. By the third there was a wheeze when he breathed out. Fon took him to the doctor, who adjusted his medication and advised reducing triggers at home, including paint and chemical odours from the repairs. Her husband was sneezing and congested more than usual too. Fon opened every window, but the rain kept coming and humidity came in instead. This picture is repeating in many families with allergy or asthma sufferers after this flood.

The 2026 Bangkok floods: thousands of homes repairing at the end of the rainy season

According to news reports, between 24 and 27 September 2026 Bangkok received roughly 300 mm of continuous heavy rain in about 48 hours. On 26 September the Bangkok Metropolitan Administration declared all 50 districts a disaster zone. Eastern Bangkok was hit hardest, with Khlong Chan and Bueng Kum among the areas mentioned. Governor Chadchart said the canals were full and drainage would take two to three days after the rain stopped. As of 30 September, roads such as Si Burapha and Lat Phrao still had 20 to 40 cm of water. Thai media compared the event with the 2011 floods, and one Thai business report cited a Chamber of Commerce estimate of around 12,300 million baht in damage.

After the water receded, repairs began across the city at once, late in the rainy season when humidity is still high, walls dry slowly and windows cannot always stay open. For most people paint and glue smells are a temporary nuisance. For people with asthma, allergic rhinitis or sensitive airways, the indoor air during this period can be full of overlapping triggers.

Understanding allergies, asthma and triggers in a repaired home

Asthma is a chronic condition in which the airways are inflamed and over-sensitive. When exposed to a trigger, they narrow, causing coughing, wheezing, chest tightness and shortness of breath. Allergic rhinitis causes sneezing, a blocked or runny nose and itchy eyes and nose. The two often occur together and share some triggers.

The triggers in a home repaired after a flood fall into two broad groups.

Group 1: allergens from damp

Public health agencies such as the CDC have long noted that mold growing after floods can trigger allergy and asthma symptoms, and advise cleaning and drying within 24 to 48 hours to limit mold growth. Damp also encourages dust mites in bedding and curtains, and cockroaches often become more common in homes after floodwater recedes.

Group 2: irritants from repairs

Volatile organic compounds (VOCs) from paint, thinner, lacquer, adhesive and epoxy, along with formaldehyde from engineered-wood furniture, are mostly not allergens themselves. They are irritants that inflame airways which are already sensitive, like pouring fuel on smouldering embers. Add fine dust from sanding walls and wood, chlorine fumes from bleach used in the clean-up, and fragrance from deodorising sprays, and the load grows quickly.

When both groups meet in the same house, symptoms may be worse than usual, and often worse at night, when bedrooms are closed, the air conditioner is running and the air does not change.

Who is most at risk

• Children with asthma, whose airways are smaller, who breathe faster and who often play on the floor near dust and odour sources.
• Adults with asthma or allergic rhinitis, especially those who work from home and stay indoors all day.
• Older people with chronic obstructive pulmonary disease, who are also sensitive to airborne irritants.
• Pregnant women with a history of allergy, who should avoid chemical vapours as far as possible.
• People sensitive to chemicals or strong smells, who get headaches, stinging eyes or nausea more easily.

Danger signs that need a doctor immediately: breathlessness so severe the person cannot finish a sentence, blue lips or fingertips, no relief from the reliever inhaler or needing it more often than the doctor advised, drowsiness or confusion, or the chest sucking in with each breath in a child. This article is not medical advice. Odour removal is not a treatment and does not replace medication or the action plan from your doctor.

What families with allergy and asthma sufferers carry

Health. More frequent flare-ups and reliever use, and sometimes emergency visits at a time when some roads are still flooded. Lost sleep from night coughing leaves people run down and more prone to respiratory infections.

School and work. A child who coughs all night goes to school sleepy and unfocused, or misses school. An adult who sneezes all day cannot work at full capacity, just when the family most needs income to pay for repairs.

Cost. Medicine, doctor visits, a second air purifier, replacement filters and temporary accommodation all pile on top of a large repair bill.

Peace of mind. Parents who lie awake listening to their child cough every night become exhausted and anxious. Some feel guilty for repairing too soon, although repairs were necessary. The real problem is that managing the air after repairs has not been completed.

Why common fixes can make things worse

Air fresheners, incense and scented candles. Synthetic fragrance and smoke are triggers doctors usually advise asthma patients to avoid. Using them to mask paint smell adds another trigger on top.

Too much bleach, or mixing products. Bleach has a role in cleaning flood residue when diluted and used as labelled, but chlorine fumes irritate the airways. Never mix bleach with products containing ammonia or acids, as this produces dangerous gases.

Running a small ozone gadget while people are home. This is the most dangerous mistake for asthma sufferers. High concentrations of ozone irritate the airways. Ozone treatment must be done in an empty, closed space, controlled by professionals, with re-entry only after the rest and ventilation period. Never run an ozone machine in a room where someone is sleeping.

Relying on an air purifier alone. A HEPA air purifier is good at capturing airborne dust and mold spores and should stay part of daily life. Dealing with chemical vapours accumulated throughout the house, in walls, furniture and curtains, is a different task that a single small unit can handle only to a limited extent.

Painting over mold spots to make them look clean. If the wall is still damp, mold keeps growing under the paint film, and the new paint adds vapours. The sufferer then faces both groups of triggers at once.

The right sequence: WHD ozone odour and chemical-residue removal

World Health Disinfection (WHD) offers an ozone odour and chemical-residue removal service for homes, condominiums, offices, hotels and other buildings. According to the service information, ozone (O3) breaks down odour molecules at the source instead of masking them. It targets paint, thinner, epoxy and lacquer odours, VOCs and musty smells, and helps deal with bacteria, viruses and mold. It then reverts to oxygen with no residue, and the space is ready to use about two hours after treatment.

For households with asthma and allergy sufferers, the key strength is measurement. WHD measures TVOC (total volatile organic compounds) with calibrated instruments before and after treatment, so the family has data to judge whether the home is ready, instead of using the patient's own airways as the test.

How the process works

1. Consultation and assessment. The team asks about the flood, the repairs, materials used and any household members with respiratory conditions, to plan how long sufferers should stay away.
2. TVOC measurement before treatment with calibrated instruments.
3. Preparing the space. Everyone, especially asthma and allergy sufferers, plus pets and plants, leaves the area. Cabinets and internal doors are opened and windows closed to create a sealed space.
4. Treatment with a Master Ozone Generator in the closed, empty space, with time and concentration controlled for the area and odour level.
5. Rest and ventilation. Ozone reverts to oxygen, then the space is aired. Nobody re-enters until the team confirms.
6. TVOC measurement after treatment, compared with the starting reading, followed by handover and advice. According to the service information, the space is ready about two hours after treatment.

Safety rules for an asthma household: ozone treatment is done only in an empty, closed space. Sufferers must be out of the house throughout treatment, the rest period and ventilation, and return only when the team confirms. We recommend that a family member without a respiratory condition goes in first and opens extra windows, then the sufferer returns, always carrying the inhaler prescribed in their action plan.

Fix damp and mold first; ozone comes last

Ozone does not replace mud removal, washing or drying. The recommended order is: remove mud and damaged items, strip out water-logged moldy materials that cannot be cleaned, wash every surface, dry the walls thoroughly, disinfect surfaces with a disinfectant used according to its label, such as Chemgene HLD4H, repair and repaint, let paint and lacquer cure as the manufacturer recommends, clean up repair dust with a HEPA vacuum or a damp cloth, and then treat with ozone as the final step before sufferers come home. Sufferers should not be in the house during cleaning or repairs.

10 reasons an allergy or asthma household should ozone-treat after repairs

1. Reduces irritants without adding fragrance. Ozone chemical-odour removal breaks down odour molecules at the source, so no new scented trigger is introduced.
2. Chemical odours and mustiness handled in one round: paint, lacquer, thinner, adhesive, epoxy and flood mustiness.
3. Helps deal with residual mold and bacteria once damp has been fixed and surfaces cleaned.
4. TVOC readings before and after, so a child's cough is not the measure of whether the air has improved.
5. Reaches the whole space. As a gas, ozone spreads into new kitchen cabinets, drawers, behind the fridge and into curtains.
6. No residue. According to the service information, ozone reverts to oxygen, leaving no chemical film on pillows, sheets or toys.
7. Done by professionals in an empty space, far safer than buying a small machine and running it with no control or measurement.
8. Quick turnaround. The space is usable about two hours after treatment, according to the service information, so sufferers need not stay away for weeks.
9. Works well with long-term care: afterwards, continue with a HEPA purifier and humidity control.
10. Helps the family sleep through the night again as airborne triggers fall. See the ozone chemical-residue removal service.

Before and after ozone: an allergy and asthma home after repairs

Note: results depend on the house, materials and curing time. Ozone does not treat asthma or allergies; sufferers should keep taking their medication and attend their appointments.

Example case: a shophouse near Si Burapha Road and an all-allergic family

(An illustrative example to explain the process, not a testimonial from a real customer.)

Jane runs a small grocery on the ground floor of a shophouse near Si Burapha Road and lives upstairs with her mother and daughter. All three have allergic rhinitis, and her twelve-year-old daughter also has asthma. The late-September flood came into the shop, ruining the shelves, and water stood outside for days after the rain stopped.

Jane sent her mother and daughter to relatives, hired cleaners, ripped out the moldy wooden shelves, repainted the walls and had new shelves built and lacquered. When the work was done the smell still drifted upstairs through the stairwell. Jane contacted WHD. The team advised her to confirm the lower walls were dry, let the lacquer cure for the manufacturer's recommended time and wipe up the sanding dust with a damp cloth first.

On the day, the team measured TVOC on both floors, confirmed the building was empty, moved fresh food stock out, opened cabinets and drawers, then sealed the space and began treatment. After the rest and ventilation period they measured again for comparison and advised Jane to open the shopfront on dry days, run an air purifier in the bedrooms and avoid air fresheners.

Jane went in first to check, then brought her mother and daughter home the following day. Her daughter carried her inhaler as her action plan requires, and Jane watched her closely through the first week and kept her doctor's appointments, because odour removal only reduces triggers at home; it is not a treatment.

Checklist for allergy and asthma households: before and after ozone

During clean-up and repairs

• Keep sufferers elsewhere throughout mud removal, stripping out moldy materials, sanding and painting.
• Whoever cleans should wear a suitable mask, gloves and boots.
• Remove water-logged, moldy materials that cannot be cleaned, such as wet gypsum ceilings, carpets or mattresses.
• Choose low-VOC paint and avoid lacquer in bedrooms unless necessary.
• Ask the doctor whether medication or the action plan should be adjusted for the return home.

Before ozone day

• Confirm walls and floors are truly dry with no new mold spots.
• Clean repair dust with a HEPA vacuum or a damp cloth.
• Let paint, adhesive and lacquer cure for the manufacturer's recommended time.
• Remove medicines, food and nebulisers or spacers from the area.
• Take out pets and plants and arrange somewhere for everyone to stay.

After ozone

• Re-enter only after the team confirms the rest and ventilation period is complete.
• Let someone without a respiratory condition go in first and open extra windows.
• Wash sheets and pillowcases in hot water where the fabric allows.
• Wash or replace air-conditioner filters, and consider cleaning the unit if it was exposed to flood humidity.
• Control indoor humidity and run a HEPA purifier in bedrooms.
• Note symptoms and inhaler use in the first week, and see a doctor at once if things get worse.

Frequently asked questions

1. Isn't ozone itself an asthma trigger? Why recommend it?

It is true that high concentrations of ozone irritate the airways. That is exactly why treatment is done only in an empty, closed space, controlled by professionals, with a rest period for ozone to revert to oxygen before ventilation. Sufferers must not be present during the process and return only when the team confirms. Never use an ozone machine in an occupied room.

2. Will ozone cure asthma or allergies?

No. It reduces odours and chemical residue in the air and on surfaces; it is not a medical treatment. Sufferers should continue their medication and doctor's plan.

3. If there is still mold, can ozone replace stripping it out?

No. Fix the damp and remove or clean moldy materials first; otherwise mold returns. Ozone is a complementary step after the source has been dealt with.

4. When can sufferers go back in?

According to the service information, the space is ready about two hours after treatment. For asthma sufferers, let another family member check and ventilate first, and ask the doctor which symptoms to watch for.

5. Does a dehumidifier help as well?

Yes, as part of the drying stage and afterwards. Keeping indoor humidity under control makes it harder for mold and dust mites to return, which matters for allergy sufferers late in the rainy season. A dehumidifier does not remove chemical vapours, though, so it works alongside ventilation and, where needed, professional ozone treatment carried out in an empty space.

6. How long should paint cure before treatment?

Follow the curing time on the paint and lacquer labels, since products differ. Treating while the coating is still wet is poor value, because it keeps releasing vapours. The team can help you judge the right timing if you contact them in advance.

7. Should we keep using an air purifier afterwards?

Yes. A HEPA purifier captures airborne dust and spores in daily life. Combined with humidity control and regular cleaning, it helps keep indoor air in good shape.

Reduce airborne triggers before bringing your loved ones home

Repairs are done but paint and chemical smells still set off coughing and sneezing? Talk to the WHD team about ozone odour and chemical-residue removal, with TVOC measured before and after.

Book Ozone Chemical-Odour Removal

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

Related pages

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

References

• 2026 Bangkok floods (Wikipedia)
• Al Jazeera: Disaster zone declared across Bangkok
• CDC: Floods, cleanup and mold
• World Health Organization fact sheets