A Typical Scenario: The Ground-Floor Accounting Office in Pathum Thani

(A typical scenario based on situations we commonly encounter. Names and details are illustrative.)

Nok is the HR manager of a mid-sized accounting firm in Khlong Luang, Pathum Thani. The office occupies the ground floor of a three-storey commercial building: about thirty staff in an open-plan room with carpet tiles, a gypsum board ceiling and four split-type air conditioners. Late in the rainy season, water from the Rangsit canal spilled over and flooded the office to roughly knee height, where it sat for almost a week. Computers were carried upstairs and everyone worked from home.

As soon as the water receded, the team moved fast. They shovelled out the mud, mopped the floor with cleaner, wiped desks with alcohol, pulled up the old carpet and laid new tiles straight away. Water-stained walls were painted over. Within ten days the office looked brand new and everyone was back at their desks. For the first week, nobody complained.

By week three and four, Nok noticed a pattern. Every morning someone asked for sick leave. One colleague described a dull headache that started around ten and lasted until home time. Another kept using eye drops. Staff with existing allergies sneezed all day, and a junior accountant with asthma was using her inhaler far more often. Strangest of all, the symptoms faded over the weekend and came back on Monday.

Clients began asking, politely, whether something smelled odd. Walking in, you noticed a damp, musty note, like laundry that never quite dried, mixed with a faint earthy smell of mud. The head of accounts complained that month-end close was slipping because two or three people were out at any one time. The owner called Nok in and asked the obvious question: how could this be happening when the office had been "cleaned from top to bottom"?

The answer was hidden in the building itself. Moisture had soaked into the lower part of the drywall, the slab beneath the new carpet, the ceiling tiles and the air-conditioner coils. Those damp materials became a breeding ground for mold and bacteria, releasing spores and volatile compounds into the air that thirty people breathed for eight hours a day. This is a textbook case of post-flood Sick Building Syndrome, and many business owners live with it without recognising it.

What Is Sick Building Syndrome, and Why Does It Follow Floods?

Sick Building Syndrome (SBS) describes a cluster of complaints experienced by people who spend time in a particular building, where symptoms are linked to time spent inside and tend to ease after leaving. Common complaints include headache, dizziness, fatigue, unusual drowsiness and poor concentration; burning, dry or itchy eyes; a blocked or runny nose; a sore or scratchy throat; a dry cough; dry or itchy skin; and, for some, chest tightness or a feeling of not getting enough air.

SBS is generally associated with poor indoor air quality. Contributors can include inadequate ventilation, chemical emissions from furnishings, dust and, most importantly after a flood, biological contaminants: mold, bacteria and the substances they release.

How a flood turns an office into an incubator

Modern offices are full of materials that absorb water extremely well: carpet tiles and broadloom, gypsum drywall, fabric-wrapped partitions, acoustic ceiling tiles, plywood and particleboard furniture, fabric chairs with foam padding, paper files and cardboard boxes stored under desks. Once these materials are soaked, or even just absorb humidity from the saturated air after the water drops, they become ideal food for mold. They contain cellulose, they hold moisture, and Thailand's warm climate does the rest.

The World Health Organization (WHO) and the US Centers for Disease Control and Prevention (CDC) both advise cleaning and drying water-damaged areas within 24 to 48 hours to limit mold growth. In reality, when floodwater stands for days, most offices cannot meet that window. By the time anyone can get inside to clean, mold has often already established itself within the materials.

The invisible culprits in office air

• Mold spores from groups commonly found in damp buildings, such as Aspergillus, Penicillium and Cladosporium. Spores are tiny, ride the air-conditioning airflow and are easily inhaled, triggering allergies and asthma.
• Mold fragments and allergens. Even dead mold can provoke allergic reactions, which is why it must be both neutralised and physically cleaned away.
• Microbial volatile organic compounds (MVOCs). These are the source of the musty, earthy, wet-laundry smell. Many people experience eye and nose irritation and headaches after prolonged exposure.
• Floodwater bacteria. Water entering an office is frequently contaminated with sewage and drain water, leaving bacteria on floors, desk legs, under cabinets and in grout lines.
• Contamination in the air-conditioning system. Damp cooling coils, drain pans and ducts can act as both a breeding site and a fan that distributes contaminants across the whole floor.

Who in the office is most at risk?

Anyone can be affected, but take particular care with employees who have allergies or asthma, pregnant staff, people with chronic conditions such as diabetes, lung or heart disease, anyone with reduced immunity due to medical treatment, older employees approaching retirement, and children who sometimes wait at the office during school holidays. Staff seated near the areas that flooded most heavily, or directly under supply vents, often report stronger symptoms.

Important: SBS is not a substitute for medical diagnosis. Anyone with a fever, a persistent cough or difficulty breathing should see a doctor. If someone waded through floodwater and later develops high fever and severe calf pain, this may signal leptospirosis and needs prompt medical attention. Tell the doctor about the floodwater exposure.

The Real Cost of Leaving a "Sick" Office Untreated

1. Employee health

Individual symptoms may seem minor on day one, but daily exposure for weeks or months wears people down. Allergies become harder to control, asthma attacks may become frequent enough to require emergency visits, pregnant employees worry about the environment they sit in all day, and some staff may resign because they feel their workplace is unsafe.

2. Money leaking out quietly

Every sick day is a cost with no output in return. Add overtime for colleagues who cover the work, medical claims under staff benefits, air purifiers bought one by one without addressing the source, and repeat repairs when mold bleeds through fresh paint a few months later. Patching the problem several times usually costs more than restoring the space properly once.

3. Lost time and productivity

Even when people show up, working through headaches, sore eyes and drowsiness reduces performance. Detail-heavy work such as accounting, legal review, design or customer service becomes more error-prone, and deadlines slip in a chain reaction.

4. Reputation and client confidence

A client who walks into a musty reception area, spots dark stains in the corners or is greeted by a sneezing receptionist in a mask will question your standards. For businesses that sell trust, such as accountants, insurers, clinics and agencies, a damaged impression can cost far more than the restoration itself.

5. Responsibility to employees' families

Staff do not get sick alone. Spores and grime travel home on clothes, bags and files, where young children or elderly relatives may be more vulnerable. The stress of working somewhere that feels unsafe also affects family life and overall morale.

Why the Usual Office Fixes Don't Work

After a flood, facility teams naturally prioritise what shows results immediately, because the business needs to reopen. Unfortunately, many common steps only treat what is visible while the causes of SBS remain in place.

• Laying new carpet over a damp slab. Concrete that sat underwater for days takes a long time to dry fully. New carpet traps that moisture underneath, creating a greenhouse for mold right beneath people's feet.
• Painting over mold on drywall. Paint hides the stain temporarily, but mold living in the gypsum core and paper facing survives and pushes through again within weeks or months.
• Wiping everything with bleach. Bleach can disinfect smooth, non-porous surfaces, but it barely reaches mold inside porous materials, and it does not reach above the ceiling, under raised floors or into ducts. Used in a closed room without ventilation, chlorine fumes add to eye and nose irritation. Never mix it with ammonia or other cleaners.
• Running fans all night. Fans help surfaces dry, but they also blow spores around the room and do nothing to the growth already embedded in materials.
• Air freshener and fragrance diffusers. Fragrance masks the musty smell for a while, but the MVOCs remain, and the fragrance itself may worsen symptoms in sensitive people.
• Buying air purifiers. A good purifier can capture some airborne dust and spores, but it cannot reach sources inside walls, under carpet or in AC coils. It is like bailing water from a boat that is still leaking.
• Washing only the AC filters. Cleaning filters is good practice, but if the coil, drain pan and blower still carry slime and mold, the smell and contamination return every time the unit starts.

In short, recovering an office after a flood has to be systematic. It needs a step that reaches the air and every corner of the room, not just the surfaces a cloth can touch.

WHD Building Ozone Disinfection: The Step That Completes Office Recovery

World Health Disinfection (WHD) provides residential and building ozone disinfection for homes, condominiums, hotels, offices, factories, schools and hospitals. For a flooded office, ozone treatment comes after mud removal, stripping out damaged materials, cleaning and drying. Its role is to deal with residual microbes and odours in the air and in corners that wiping cannot reach. It does not replace cleaning, drying or medical care.

How ozone works

Ozone (O₃) is a strongly oxidising gas. When it fills a sealed room, it breaks down the cell structures of viruses, bacteria and mold, and breaks apart odour molecules such as musty and mud smells. Ozone then reverts to oxygen (O₂), leaving no chemical residue on desks, keyboards or documents, unlike heavy liquid spraying that can leave films or smells behind. Because it is a gas, it reaches places cloths cannot: under long desk runs, behind filing cabinets and into the room's air pathways.

According to the test results certified for the company, WHD's service has been tested and certified by Thailand's Department of Medical Sciences and Intertek (UK) for eliminating viruses, bacteria and mold by 99.99%. You can review the certification documents on our website.

The office ozone process

1. Survey and zoning. The team assesses the space and divides it into zones such as the open-plan floor, meeting rooms, executive offices, file room, pantry and restrooms, then schedules the job when the building is empty, for example Friday evening or the weekend.
2. Preparation. Everyone leaves the area, including any office pets, and potted plants are removed. Doors and windows are closed, air conditioning is set as advised, and drawers and cabinet doors are opened so the gas can reach inside.
3. Ozone fill. Ozone generators fill the sealed zone.
4. Contact time. Ozone is allowed to react with microbes and odours. A typical cycle is about 30 minutes per zone, depending on size and condition.
5. Rest and ventilation. The ozone is left to revert to oxygen, then the zone is ventilated before anyone is allowed back in, following the team's instructions.
6. Handover and aftercare advice. The team summarises the work and advises on humidity control so mold does not return.

Safety first: ozone treatment is carried out only in an empty, closed space. No people, pets or plants may remain during treatment, and re-entry is allowed only after the rest and ventilation period. High-concentration ozone irritates the airways, so the work must be done by a trained team.

Promotion: book an ozone job of 15,000 baht or more and receive a free medical-grade disinfectant spray for keeping shared touchpoints clean after you reopen.

10 Reasons Flooded Offices Choose WHD Ozone Treatment

1. It targets indoor air quality directly. SBS is about the air everyone shares, so a gas that fills the room fits the problem better than wiping surfaces alone.
2. It reaches the dead corners. Under rows of desks, behind steel cabinets, cable trays and partition gaps.
3. No chemical film on office equipment. Ozone reverts to oxygen, leaving nothing on keyboards, screens or paperwork.
4. It tackles odour at the source. Odour molecules are broken down rather than covered with perfume, so visitors notice fresh air.
5. Backed by testing. According to the company's certified test results from the Department of Medical Sciences and Intertek (UK), 99.99% elimination of viruses, bacteria and mold. Details are on our ozone service page.
6. Fast, with minimal downtime. About 30 minutes per zone per cycle, scheduled for evenings or weekends so you open as normal.
7. Flexible zoning. Treat one floor or one department at a time, ideal when part of the building must stay open.
8. Confidence for returning staff. HR can clearly communicate that the office was restored systematically, not just repainted.
9. A safety-focused professional team. Empty, sealed spaces and clearly defined re-entry times. Learn more about our building ozone disinfection.
10. Part of a complete hygiene programme. Combine it with our disinfection service and touchpoint products, plus the free medical-grade spray on jobs from 15,000 baht.

Example Case: A Creative Agency in Nonthaburi

(An illustrative example case, not a named customer review.)

Ton runs a small advertising agency in Pak Kret, Nonthaburi, renting the ground floor of an office building near the Chao Phraya River. The office flooded to about ankle-to-shin depth for four days. Afterwards, the team scrubbed floors, wiped desks and reopened within a week because client work was waiting.

About a month later, the creative team complained that the small windowless meeting room smelled strange and that long sessions in it left them with headaches. Two designers sitting in the corner where water had lingered longest developed a constantly blocked nose. Ton bought two air purifiers; they helped a little, but the smell never went away.

A contractor inspection found that the lower drywall of the meeting-room partition was still damp with mold on its inner face, and the meeting-room AC drain pan was coated in slime. Ton reset the plan: cut out the damaged lower drywall, let the frame dry completely, deep-clean the AC system, install new boards, and then book WHD to ozone-treat the whole office on a Saturday in four zones. Everyone stayed out of the building and returned only after the ventilation period advised by the team.

In this example, when staff returned on Monday, the meeting-room odour was gone and the overall atmosphere felt noticeably better. Ton also introduced new habits: a dehumidifier in windowless rooms and a monthly AC drain-pan check. The designers with lingering symptoms were encouraged to see a doctor for allergy testing. The lesson: ozone works best after the moisture source has been removed, never instead of repairs.

Office Flood Recovery Checklist: Before and After Ozone

Before entering

• Have an electrician or building manager check the electrical system; never switch on power while floors are wet.
• Cleaning crews should wear boots, rubber gloves, a suitable dust mask and eye protection.
• Photograph all damage for insurance and asset records.

Cleaning and drying

• Remove all mud and debris; strip out soaked carpet, wet ceiling tiles and saturated insulation.
• Cut out wet lower drywall so the frame can dry. Do not paint over it.
• Wash floors and hard surfaces, then disinfect following product instructions.
• Use dehumidifiers and industrial fans until floors and walls are truly dry before installing new flooring.
• Clean the entire AC system, including coils, drain pans and blowers, not just filters.
• Separate wet important documents for specialist handling.

On ozone day

• Tell staff in advance that the building is off-limits during the scheduled window.
• Remove potted plants, aquariums and any animals.
• Open drawers, cabinets and inner doors as the team advises.
• Re-enter only after the team confirms the rest and ventilation period is complete.

After ozone

• Keep indoor humidity under control, ventilate regularly and run dehumidifiers in stuffy rooms.
• Schedule regular AC cleaning and drain-pan checks.
• Wipe shared touchpoints such as door handles, lift buttons and copiers.
• Check in with staff; anyone with continuing symptoms should see a doctor, and the building should be re-inspected.

Frequently Asked Questions

Q: If we ozone the office, can we skip removing soaked carpet and drywall?
A: No. Water-damaged materials that are still wet must be removed or dried first. Ozone is an added step after cleaning and drying to address residual microbes and odours, not a replacement for repairs.

Q: Can a few people keep working in the room during treatment?
A: Absolutely not. The treated area must be empty and sealed, with no people, pets or plants, and re-entry is allowed only after the rest and ventilation period the team specifies.

Q: How long does it take? How many days must we close?
A: A typical cycle is about 30 minutes per zone, plus preparation and ventilation. Most offices can be treated in an evening or over a weekend and open the next working day, depending on size.

Q: Will ozone damage computers or documents?
A: The team assesses the space and advises before starting. Ozone reverts to oxygen and leaves no liquid residue on equipment. Let the team know in advance about special documents or valuables so you can plan together.

Q: Will staff SBS symptoms disappear immediately?
A: Ozone helps reduce residual microbes and odours, but it must go hand in hand with moisture removal and good ventilation. Anyone with ongoing symptoms should see a doctor, as other causes may be involved.

Q: How often should we repeat treatment?
A: It depends on whether any moisture source remains. Once the cause is fixed, many businesses repeat treatment periodically, for example before the rainy season or after a leak. The team can advise based on your building.

Q: Which buildings do you serve?
A: WHD serves homes, condos, hotels, offices, factories, schools and hospitals. See the service page or contact us.

Give Your Team an Office They Can Breathe In

Talk to WHD about post-flood office ozone treatment, zoned to your floor plan and scheduled around your working week.

Book Office Ozone Disinfection

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

Related Services

• Residential and Building Ozone Disinfection
• Ozone Cleaning Service
• Disinfection Service
• Certification Documents

References

• World Health Organization – Fact sheets
• CDC – Floods and cleanup guidance