A typical scenario (an illustrative situation based on common cases, not a review from a specific customer)

A Khlong Chan townhouse and three methods already tried

Em and his wife, six months pregnant, live in a three-storey townhouse in Khlong Chan. During the heavy rain at the end of September 2026, water flooded the entire ground floor. The plastered walls soaked up water until the paint blistered and peeled in sheets, the timber doors swelled and the particleboard shoe cabinet fell apart. The couple retreated upstairs for several days until the water drained and repairs could start.

The painter scraped off the blistered paint, let the walls dry as much as possible, rolled on a damp-proof primer and two topcoats, re-varnished the doors and regrouted the ground-floor tiles. The work took five days. But the smell drifted up the staircase into the second-floor bedroom, and Em's wife felt nauseous and headachy every time she went downstairs.

First they opened every window and door all day. But the rain kept coming back, humidity flowed in, the new paint looked damper than before, and the smell of standing water from the street mixed in. Next they bought an air purifier for the ground floor. It ran quietly and its air-quality light glowed green, yet the paint smell barely changed. They began to wonder whether they had chosen wrongly, or simply had not waited long enough, and whether the third option, ozone, was suitable for a home with a pregnant woman.

The answer is not to pick one method and discard the others. It is to understand what each does and when to use it.

The late-September 2026 floods and the wave of repainting that followed

According to news reports, roughly 300 mm of rain fell in about 48 hours between 24 and 27 September 2026, flooding large parts of Bangkok. On 26 September the BMA 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, and as of 30 September some roads, including Sri Burapha and Lat Phrao, still had around 20 to 40 cm of water.

As the water receded, a wave of repairs followed. Soaked walls blister, peel or stain, so scraping and repainting is among the most common jobs: damp-proof primers, acrylic emulsions, oil-based paint for frames and doors, varnish, lacquer and epoxy in some areas. All of these release volatile organic compounds (VOCs), the main cause of paint smell.

The particular problem now is that the air is still humid and rain keeps returning. Walls that were submerged still hold moisture in the plaster, so paint dries more slowly and the smell lingers far longer than many people expect. At the same time families want to move back as soon as possible, so choosing the right odour strategy directly affects both health and daily life.

What paint smell is, why it lingers, and who is most at risk

Most paint smell comes from solvents and additives evaporating as the paint dries and cures. Oil-based paint and thinner tend to smell strong and sharp; water-based paint smells milder but still releases volatiles early on. Varnish, lacquer and epoxy have distinctive odours that can persist, especially in closed rooms.

Emission happens in two phases. First, while the paint is wet, it releases the most. Second, once the surface is touch-dry but the film is still curing, it keeps releasing smaller amounts over a longer period. On damp post-flood walls, this second phase can stretch out, and the released vapours are absorbed by curtains, mattresses, sofas and rugs, so the smell stays even after the walls themselves have quietened down.

Possible symptoms and vulnerable groups

Breathing heavy paint vapour in a closed room can irritate the eyes, nose and throat and cause headaches, dizziness, nausea or fatigue. Pregnant women, babies and young children, older adults, and people with asthma, allergies or chronic lung disease should avoid freshly painted rooms. Anyone with breathing difficulty, chest tightness or symptoms that persist after leaving the area should see a doctor. Anyone who waded through floodwater and then develops fever, calf pain or diarrhoea should also see a doctor, as this may be leptospirosis or another water-borne illness that needs treatment and has nothing to do with odour.

The real cost of a lingering paint smell

Health. Days of living with paint fumes mean poor sleep and recurring headaches, and in homes with a pregnant woman, small children or elderly relatives the worry multiplies.

Money. Temporary accommodation, travel to and from relatives, extra purifiers, fragrances and charcoal bags all add up, just when the family has already spent heavily on repairs.

Time. The longer the smell lingers, the later you get your rooms back. For people who work from home or run a small shopfront, every lost day is lost income.

Family and reputation. Flood fatigue leaves everyone on edge, and sleeping apart adds stress. For landlords and shop owners, a tenant or customer greeted by a sharp paint smell forms a poor first impression immediately.

Method 1: Opening windows for natural ventilation

How it works. Opening windows dilutes paint vapour with outdoor air. The more breeze and the more cross-ventilation between openings on opposite sides, the faster the indoor air is replaced. A fan blowing out of a window boosts the flow.

Strengths. It is free, immediate and should always be done during painting and while paint is fresh. Many public-health bodies recommend good ventilation during and after painting.

Limits after a flood:

• Effectiveness depends on wind and orientation. Townhouses and shophouses with openings on one side ventilate slowly.
• In rainy, humid weather, an open house lets moisture in, slowing both paint drying and the drying of flood-soaked walls.
• Homes beside streets with standing water may simply swap paint smell for stagnant-water and fuel odours.
• Leaving a house open day and night raises security, mosquito and dust issues.
• Dilution does not destroy odour molecules. Vapour absorbed into curtains, mattresses and upholstery keeps seeping out.

Verdict. Ventilation is the essential foundation, but during a wet post-flood period it can be slow and hard to control.

Method 2: Air purifiers, what they can and cannot do

How they work. Most home purifiers use a HEPA filter designed to capture particles such as PM2.5 dust, pollen and some mold spores. Paint smell is not a particle; it is a gas, vapour molecules far smaller than anything HEPA is designed to trap.

To help with paint smell, a purifier needs an activated-carbon filter, which adsorbs some gas molecules into the carbon's pores. Performance depends on how much carbon is in the unit. A thin carbon sheet saturates quickly; once saturated it cannot adsorb more, and with heavy paint odour you may need to replace filters more often than usual.

Strengths. It runs continuously while people are present, is good for maintaining bedroom air once most of the smell has gone, and handles renovation dust well.

Limits:

• A HEPA filter alone does little for paint smell.
• Many air-quality indicators mainly sense dust, so a green light does not mean no paint vapour.
• Each unit covers a limited area; a whole repainted floor may need several.
• Carbon saturates, and it stores chemicals rather than destroying them.
• Some purifiers emit ozone or use certain ionising systems; do not run these in occupied rooms unless the manufacturer certifies it safe. Read the manual carefully.

Verdict. A carbon-equipped purifier is good for ongoing maintenance, but not the main tool for clearing heavy paint odour from an entire floor.

Method 3: WHD's ozone chemical-odour removal service

World Health Disinfection (WHD) offers an ozone service for chemical residue and odour removal. 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, as well as bacteria, viruses and mold. Afterwards ozone reverts to oxygen with no residue, and the space is ready to use about two hours after treatment. The team uses a Master Ozone Generator and measures TVOC with calibrated instruments before and after. The service covers homes, condos, offices, factories, construction sites, hotels, storage and automotive settings.

Strengths. As a gas, ozone spreads through the whole closed space, including corners, behind cabinets and into curtains and upholstery where paint vapour has soaked in. It does not depend on wind or weather, finishes in one session and comes with before-and-after TVOC figures.

Limits and conditions:

• Treatment is done only in an empty, closed space. People, pets and plants must leave and return only after the rest and ventilation period ends.
• Schedule it after all painting is finished and touch-dry; any new coat will release fresh odour.
• It does not replace mud removal, washing, drying and surface disinfection, and it is not medical treatment.
• Some new materials keep off-gassing from within, so regular ventilation is still needed afterwards.

The process in brief

1. Review the flood history, repairs, paint types and painting dates.
2. Take baseline TVOC readings at defined points.
3. Seal the space; everyone, including pets and plants, leaves.
4. Treat with the Master Ozone Generator according to area.
5. Stop, let ozone revert to oxygen, then ventilate.
6. Re-measure TVOC at the same points and explain results and aftercare.

Side-by-side comparison

This is a comparison of principles; real results depend on area, paint type, humidity and equipment model.

Popular tricks that fall short

Fragrance sprays and scented candles only cover the smell briefly, and fragrances add their own VOCs.

Bowls of coffee, onion or lemon may slightly soften the perception of odour in a small space, but do not meaningfully reduce what is in the air.

Running the air-conditioner with the room shut recirculates the same air in most homes. The smell circulates and can settle into the coil and filter.

Repainting because you suspect the first paint adds a new source, and on still-damp walls the paint may blister again.

Running a cheap ozone machine yourself while at home is something you should not do. Ozone must be used in a sealed space with no people, pets or plants, followed by a rest and ventilation period. Leave it to professionals with proper equipment and safety procedures.

The winning formula: each method at the right moment

The three methods are not competitors. They do different jobs at different stages of recovery.

1. During painting and right after. Open windows and use fans to push air out. Painters should work in moving air; vulnerable family members should stay elsewhere.
2. When all painting and repairs are done and touch-dry. This is the moment for ozone paint-odour removal, clearing smell from air, fabrics and corners in one session with TVOC measured before and after.
3. After moving back. Ventilate regularly and run a carbon-equipped purifier in bedrooms for ongoing care, especially rooms with new furniture.

For homes with a pregnant woman, young children or elderly relatives, this sequence keeps vulnerable people away from the worst of the fumes and brings them home when the house is genuinely ready.

Four questions to decide which mix suits your home

How much was painted? One touched-up wall in a breezy room may only need ventilation. A whole repainted ground floor plus varnished doors and new cabinets is a different scale of odour load.

How well can the house breathe? Corner houses with windows on several sides air out far faster than mid-row townhouses or shophouses with openings at the front only. Condos with sealed windows depend almost entirely on mechanical ventilation.

Who will live there? If the household includes a pregnant woman, a newborn, an elderly parent or someone with asthma, the margin for "waiting it out" is smaller, and a planned, measured approach is worth more.

How soon do you need the space? A family paying for a temporary room, or a shop losing trade every day it stays closed, may value a single treatment with a clear re-entry time over weeks of uncertain airing. Answering these four questions honestly usually makes the right combination obvious.

10 reasons flood-repaired homes should consider ozone for paint smell

1. No waiting for dry weather. Ozone does not depend on wind or outdoor conditions.
2. Breaks odour down at the source. Per the service information, ozone destroys odour molecules rather than diluting or storing them.
3. Reaches every corner of the sealed space, including curtains, sofas and behind cabinets.
4. No residue, because ozone reverts to oxygen.
5. Handles many odours at once: paint, thinner, varnish, lacquer, epoxy and flood mustiness.
6. Hygiene bonus. Per the service information, ozone also targets bacteria, viruses and mold after surfaces have been washed and disinfected.
7. Measured results with calibrated before-and-after TVOC readings.
8. Fast return, with the space ready about two hours after treatment.
9. Safe when done properly. The team ensures the space is empty and sealed and tells you exactly when to return.
10. Works for many spaces, from homes, townhouses and condos to offices, shops and factories. See the service page for details.

Before and after: paint odour handled at the right time

Note: results vary with paint type, wall moisture, area and household materials.

Example case (a hypothetical scenario reflecting common problems, not a real customer review)

Em in Khlong Chan: stop choosing one method, use each at the right time

After talking with the team, Em took his wife to stay with her mother for two days. Meanwhile the painter finished varnishing the doors, Em took the ground-floor curtains down to wash, and he opened the windows whenever the rain paused so the paint could dry. Once everything was done, the WHD team took baseline TVOC readings, asked everyone to leave, sealed the space and treated it with a Master Ozone Generator, then rested and ventilated before measuring again at the same points.

The after readings had clearly dropped. The team suggested moving the purifier Em had bought into the upstairs bedroom and switching to a filter with more carbon, to look after the room where his wife spends most time, and reminded him to keep ventilating whenever the weather allowed.

Em's lesson: the purifier was not a waste and opening the windows was not wrong. Both had simply been used at the wrong moment for the wrong job. Once each method played its own role, the house felt like home again.

Checklist before and after ozone paint-odour treatment

Before

• Remove mud, wash and dry the house before painting. Public-health guidance generally advises cleaning and drying quickly, ideally within 24 to 48 hours, to limit mold.
• Disinfect flood-contaminated surfaces after the mud is gone, for example with Chemgene HLD4H at the label dilution and contact time.
• Finish all painting, varnishing and lacquering, and let it become touch-dry.
• Wash removable curtains, pillowcases and covers.
• Arrange somewhere for family and pets to stay, and move plants out.
• Pack away food, medicines and personal items.

After

• Re-enter only after the rest and ventilation period the team specifies.
• Ventilate regularly when the weather allows.
• Run a carbon-equipped purifier in bedrooms and change filters on schedule.
• Avoid more painting or heavy fragrance use at first.
• Watch for symptoms and see a doctor if anything is unusual.

Frequently asked questions

1. If my house ventilates well, do I still need ozone?

If the house airs well, the weather is dry and the smell has faded to nothing bothersome, maybe not. In a wet post-flood period, with few openings and vulnerable people at home, ozone helps you move back sooner and with more confidence.

2. Will a HEPA purifier help with paint smell?

HEPA captures particles, not gases. For paint smell, choose a unit with a substantial activated-carbon filter.

3. Can a pregnant woman stay home during ozone treatment?

No. Everyone leaves during treatment, along with pets and plants, and returns only after the rest and ventilation period. Anyone with health concerns should consult their own doctor.

4. When is the best time for ozone?

After all repairs and painting are complete and touch-dry, before the family fully moves back in.

5. How long before we can go back in?

According to the service information, about two hours after treatment. Follow the time the team gives on site.

6. Can I buy an ozone machine and use it myself?

Never run an ozone machine with people in the home. Safe ozone use requires a sealed space, sizing to the area and a rest and ventilation period. Let professionals handle it.

Freshly painted but the smell will not leave? Let WHD clear it in one session.

Ozone removal of paint, thinner and chemical residue odours, with TVOC measured before and after.

Ask about ozone paint-odour removal

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

Related links

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

References

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