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

The house looked brand new, but the four-month-old cried every time he was carried downstairs

Beer and Prae, a couple in their early thirties, bought their first detached house in a small estate off Si Burapha Road less than two years ago. Their first son is four months old. In the last week of September 2026 heavy rain fell for days, the soi flooded, and water about a hand-span deep entered the ground floor and stayed for several days. When it left, a brown tide line circled every room, the paint blistered and peeled in places, and small black spots appeared along the bottom of the walls.

They did not want their son living with that for long. As soon as the road dried, Beer bought several buckets of acrylic emulsion, a damp-resistant primer and an anti-mould paint, and two friends helped repaint the whole ground floor in a single weekend so the family could move back before the working week. The result looked fresh and clean. But from the first night, a sharp paint smell filled the ground floor, and it got stronger when they switched on the air-conditioning and closed the windows against the passing showers.

Prae had headaches by afternoon and stinging eyes in the living room. The baby fussed whenever he came downstairs. They tried halved onions, coffee grounds and charcoal in every corner, and ran fans all day. A week later the smell was still there, and now a faint musty note was creeping out of the walls that had carried the flood line. When will the paint smell go, is it safe for the baby, and why does a freshly painted wall smell musty?

Many Bangkok families who rushed to repair after the water receded are facing the same thing. This article explains where paint odour comes from, why flooded homes hold it longer, the correct order for repainting and odour reduction, and how the ozone odour and chemical-residue removal service from World Health Disinfection (WHD) can help.

Why so many Bangkok homes are being repainted at once

According to news reports, around 300 mm of rain fell on Bangkok in roughly 48 hours between 24 and 27 September 2026, and on 26 September all 50 districts were declared a disaster zone. Eastern Bangkok was hit hardest. Governor Chadchart said the canals were full and drainage would take two to three days after the rain stopped. As of 30 September, reports said 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 a Thai business report cited a Chamber of Commerce estimate of about 12,300 million baht in damage.

Once the water is gone, the first instinct is to erase the visible traces: tide lines, blistered paint and mould spots. Hardware stores are busy and painters have long queues. But painting in large numbers while the air is still humid and rain still falls has made "the paint smell that will not go away" a problem many families now share.

Where paint smell comes from: understanding VOCs

Every house paint contains pigment, binder, a solvent or water carrier, and additives. As paint dries and cures, solvents and some additives evaporate into the air. These are volatile organic compounds, or VOCs, and they are the main source of the "new paint" smell.

Solvent-based versus water-based paint

Oil-based and solvent-based products, such as some gloss enamels, anti-rust paints and anything thinned with thinner, have a sharp smell and release a lot of VOCs early on. Water-based acrylics, the usual choice for interior walls, smell milder, but that does not mean they contain no VOCs. Coalescing agents and additives can keep evaporating for days or weeks, especially with several coats or poor ventilation.

Damp-resistant primers and anti-mould paints

Flooded homes often need extra products: primers for old render, damp-resistant sealers, waterproofing liquids or paints with anti-mould additives. Some of these contain stronger solvents than the topcoat. Layering several products in a short time stacks multiple VOCs in the house at once.

Touch-dry is not the same as cured

Touch-dry paint does not stick to your finger, but the film takes longer to cure fully, and VOCs keep escaping meanwhile. How long depends on paint type, thickness, number of coats, temperature, humidity and airflow, as described on the manufacturer's label or data sheet.

Why flooded homes hold paint smell longer

1. Humid air and continuing rain slow drying

After the floods, Bangkok's air remains very humid and many homes keep windows shut against showers. High humidity slows evaporation of water and solvents, so drying and curing stretch out and the smell lingers longer than it would in the dry season.

2. Painting over walls that are not truly dry

Masonry that sat in water for days holds moisture deep inside even when the surface looks dry. Paint over it and the moisture is trapped. The paint may blister, peel or show white salt deposits, and the trapped damp feeds mould. You end up with fresh paint smell and a musty smell from behind the paint at the same time.

3. Many coats and products in a short time

To finish quickly, primer, sealer and several topcoats often go on within a day or two, without waiting the recoat times the manufacturer specifies. Solvents from lower layers are sealed under upper ones and seep out for a long time.

4. Closing up and running the air-conditioner too soon

Most home air-conditioners recirculate indoor air rather than bring in fresh air. Switch on the AC and shut the room straight after painting and the VOCs simply circulate, with some absorbed into curtains, sofas, mattresses and rugs, to be released again later.

5. New furniture and other repair materials

Post-flood repairs rarely stop at paint. New plywood cabinets, skirting, doors, flooring, adhesives, sealants and floor coatings all release their own volatiles. Combined with paint, the house carries a chemical blend that is hard to tell apart.

How paint VOCs affect health, and who should be most careful

Short-term exposure to paint VOCs commonly causes headaches, dizziness, nausea, stinging or watering eyes, an irritated nose and throat, coughing and fatigue. Symptoms usually ease in fresh air. The WHO and many environmental agencies stress indoor air quality because people spend most of their time indoors, so reducing exposure to volatile chemicals at home is worth the effort.

People who need extra care

• Babies and young children, who breathe faster, weigh less and often sleep or play in the freshly painted room.
• Pregnant women, who should avoid painting themselves and not sleep in newly painted rooms; ask a doctor about any concerns.
• Older adults and people with heart or lung conditions.
• People with asthma or allergies, especially when mould spores from previously flooded walls are also in the air.
• Pets, particularly birds and cats, which are sensitive to airborne chemicals.

If anyone has difficulty breathing, chest tightness, severe dizziness or symptoms that do not improve in fresh air, see a doctor. Fever, calf pain or diarrhoea after wading through floodwater may signal leptospirosis or another infection and also need a doctor. Reducing paint odour is not medical treatment.

What a week of lingering paint smell costs

Health: constant headaches, poor sleep and irritability during physically demanding recovery work, plus a fussing baby who keeps parents awake.

Money: extra nights in temporary accommodation, an air purifier bought in a hurry, or a second repaint in a "better" brand, when the real problem is damp walls or poor airflow.

Time: waiting for the smell to fade on its own in humid weather can take far longer than a family can wait, leaving finished rooms unusable.

Business and reputation: clinics, cafés, salons, offices and rental units reopening after the flood lose customers when a sharp chemical smell greets them at the door. New tenants postpone move-in dates, and online reviews can linger.

Family: the feeling that a just-repaired home is still not safe for the children adds stress at a time when everyone wants life to get back to normal.

Why home remedies do not finish the job

1. Onions, lemons, coffee grounds and charcoal

They may add their own scent or absorb a little odour in a small space, but they cannot deal with VOCs steadily evaporating from every wall. Onions left out for days can rot and add a new smell.

2. Air fresheners and perfume

Spraying fragrance over paint smell adds another set of volatiles to the air. The paint odour is masked, not removed, and for sensitive people the mix can make headaches worse.

3. Cool AC in a closed room

It feels better for a while, but VOCs keep circulating and soaking into fabrics. When the AC goes off or the room warms, the smell comes back.

4. Repainting with another brand

If the cause is damp in the wall or coats applied too fast, another repaint only adds VOCs and traps moisture deeper. The musty smell will still follow.

5. Just waiting

Paint smell does fade over time, but in humid weather and a closed house it may take longer than a family with a baby or a sick relative can wait, and everyone keeps breathing the VOCs meanwhile.

The right order: repair, repaint and reduce odour safely

1. Remove mud and wash the walls with clean water and detergent. Scrape off blistered paint and clean away mould.
2. Disinfect the cleaned surfaces with a disinfectant used according to its label, such as Chemgene HLD4H medical-grade disinfectant, at the stated dilution and contact time, with gloves and ventilation.
3. Let the walls truly dry, not just the surface. Use fans or dehumidifiers and have a painter check moisture before painting. Gypsum board that soaked and softened should be replaced, not painted over.
4. Choose suitable paint. Where possible pick paints the manufacturer describes as low-VOC, and use a primer suited to previously wet walls, as the manufacturer advises.
5. Follow label recoat times, letting each coat dry before the next, with windows open and extractor fans running during and after painting.
6. Keep vulnerable people away. Babies, pregnant women, older relatives and pets should stay elsewhere during painting and the first period afterwards.
7. Ozone treatment once the paint has dried as the manufacturer recommends, to deal with paint odour and VOCs still in the air and fabrics, along with any residual mustiness.

The WHD ozone paint-odour and chemical-residue removal service

According to World Health Disinfection's service information, ozone (O3) oxidises odour molecules and breaks the odour-causing compounds apart at the source instead of covering them. The service targets paint, thinner, epoxy and lacquer odours, VOCs and musty smells, as well as bacteria, viruses and mould. Once the reaction is complete, ozone reverts to oxygen and leaves no residue.

For a freshly repainted flooded home, the advantage is that ozone is a gas that spreads through the whole room, reaching curtains, sofas, mattresses and cabinets that have absorbed paint smell, and it addresses mustiness from previously wet walls at the same time.

How the work is done

1. Questions about the paint job: paint type, number of coats, finish date and flood depth, to check the paint has dried as the manufacturer recommends.
2. TVOC measured before treatment with calibrated instruments, according to the service information, to set a clear baseline.
3. The space is emptied. People, pets and plants leave; doors and windows are closed; cupboards and drawers opened as advised.
4. Treatment with a Master Ozone Generator in the empty, closed space, at the concentration and duration set for each zone.
5. Rest and ventilation while ozone reverts to oxygen, then airing. According to the service information, the space is ready about two hours after treatment.
6. TVOC measured again so the owner sees before and after figures.

Safety: ozone treatment is carried out only in an empty, closed space. People, pets and plants stay out and return only after the rest and ventilation period. Treat after the paint has dried per the manufacturer's guidance, never while it is still wet.

More details on the ozone paint-odour and chemical-residue removal service page.

10 reasons to ozone a freshly repainted flooded home before moving back fully

1. It reduces paint odour at the source by breaking odour molecules apart instead of perfuming over them.
2. It targets lingering VOCs. According to the service information, the service is designed specifically to reduce volatile organic compounds. Read more on the chemical-odour ozone service page.
3. It reaches curtains, sofas and mattresses that soaked up paint smell and keep releasing it.
4. It handles mustiness from previously wet walls at the same time, since ozone works on musty odours and mould.
5. No residue. Ozone reverts to oxygen, which suits homes with babies and older relatives.
6. Before and after TVOC figures, so you do not have to guess by nose.
7. A fast return, about two hours after treatment according to the service information.
8. Shops and offices reopen sooner without customers meeting a wall of paint smell at the door.
9. Professional equipment, a Master Ozone Generator with safe timing control. See the WHD ozone service.
10. It completes the repair. The house does not just look new; the air inside is clean again too.

Example case: a rental townhouse near Khlong Chan where new tenants postponed moving in

This example case is a hypothetical scenario built from common problems to illustrate the process. It is not a real customer review.

Pom owns a rental townhouse near Khlong Chan that flooded in late September. The previous tenant had left, and a new family with young children was due to move in early October. Pom hired painters to scrape the blistered paint, prime and repaint the ground floor, and replaced the skirting and a bathroom door.

When the new tenants came to view, the paint smell was strong and some walls showed damp patches, so they asked to postpone. Checking with the painter, Pom found the back wall beside the laundry area was still damp because it had been painted too soon.

The paint on the damp section was scraped off, the wall dried with a dehumidifier for several days, then primed and repainted following the manufacturer's recoat times, with continuous ventilation. Once the paint had dried as recommended, ozone was booked with nobody in the house. TVOC was measured before, the house treated zone by zone, rested and ventilated, then measured again.

In this example the reading after treatment was lower than before, the paint smell faded enough to satisfy the tenants, and Pom could show them the figures. His lesson: without fixing the damp wall first, the mustiness would return however many times the house was treated.

Checklist: repainting after a flood and reducing paint smell

Before painting

• Wash off flood stains, scrape blistered paint and clean away mould.
• Disinfect cleaned surfaces according to the product label.
• Let walls dry properly and have the moisture checked.
• Replace soaked, softened gypsum or plywood.
• Choose low-VOC paints where possible.

While painting

• Open windows and run extractor fans.
• Wait for each coat to dry as the label specifies.
• Keep babies, pregnant women, older relatives and pets elsewhere.
• Seal paint tins and store them outside the house.

Before and after ozone

• Wait until the paint has dried as the manufacturer recommends.
• Remove paint tins, thinner and leftover materials from the house.
• Make sure all people, pets and plants are out during treatment.
• Return only after the rest and ventilation period the team specifies.
• Keep ventilating for the first days and watch for mould on the walls.

Frequently asked questions

1. Can I ozone straight after painting?

No. Wait until the paint has dried for the time the manufacturer specifies. The team will ask about the paint and finish date to plan the right day.

2. If I plan to ozone, can I skip waiting for the walls to dry before painting?

No. Damp walls must be dried. Ozone does not dry walls and does not replace repairing damaged ones.

3. Do we have to leave the house during treatment?

Yes. Ozone treatment happens only in an empty, closed space. People, pets and plants stay out until the rest and ventilation period is complete.

4. When can the baby come back?

According to the service information, the space is ready about two hours after treatment. Keep ventilating on the first day, and talk to a doctor about any health concerns for your child.

5. How will I know the paint smell has really dropped?

According to the service information, WHD measures TVOC with calibrated instruments before and after, so you can see the result in figures.

6. Can shops and offices use this service?

Yes. WHD serves homes, condos, offices, factories, construction sites, hotels, storage and automotive spaces.

7. Is a low-VOC paint enough on its own?

Choosing a low-VOC paint is one of the best decisions you can make, but it does not cancel out the other factors. Primers, sealers, adhesives and new furniture still release volatiles, and humid weather still slows curing. Low-VOC paint plus dry walls, proper recoat times and good ventilation gives the best starting point, and ozone then deals with what remains in the air and fabrics.

8. Does ozone stop the flood from happening again or protect the new paint?

No. Ozone does not prevent flooding and does not protect paint from future water damage. It reduces odour, VOCs and residual germs during recovery. For future heavy rain, follow BMA announcements and consider practical steps such as raising sockets and storing valuables upstairs.

Repainted after the flood and the paint smell is still there?

Let the WHD team assess the space, measure TVOC and plan a safe ozone treatment, so your family can breathe freely in the home you have just repaired.

See the Ozone Paint-Odour Service

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

Related pages

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

References

• Wikipedia: 2026 Bangkok floods
• Al Jazeera: Disaster zone declared across Bangkok
• WHO fact sheets
• CDC: Floods