Dengue Swept a Worker Camp and the Build Stalled - How a Contractor Took Control With the Airofog U260
Last updated: 2 Sep 2026 | 13 Views |
Dengue Swept a Worker Camp and the Build Stalled - How a Contractor Took Control With the Airofog U260
A construction site holds standing water in a dozen places by the nature of the work, and the worker camp is where hundreds of people sleep a few dozen metres from all of it. Every contractor knows this equation. Very few manage it systematically.
What actually happened — Nine cases in two weeks, and a delay that hit on three levels
Prasert manages construction of an 18-storey office building on the outskirts of Bangkok, with around 340 workers on the project, 210 of whom live in the worker camp inside the site boundary.
The camp is a two-storey temporary building: 34 shared bedrooms sleeping six to eight each, twelve shared bathrooms, a central canteen and a shared laundry yard.
September is the wettest month of the year. Foundations were complete, but the site still had settling ponds, water tanks for concrete work, unfilled pile holes, a stack of old truck tyres in one corner, and formwork holding rainwater in its channels - spread across the whole area.
Prasert says the first worker to fall ill was a 32-year-old steel fixer with a high fever and body aches severe enough that he could not work. His supervisor gave him two days off, assuming flu.
On the third day he got worse. He was taken to hospital and diagnosed with dengue.
The following week four more workers presented similarly, two requiring hospital admission. In the second week, four more. Nine cases in a fortnight.
The impact on the build arrived on three levels simultaneously.
First, direct manpower. The nine workers missed 74 days between them, and because dengue leaves prolonged fatigue, those who returned worked below capacity for days afterwards.
Second, fear spreading through the workforce. Eleven workers resigned and went home within the month - and in a tight construction labour market, replacements take about three weeks to find.
Third, the local health authority visited the site following the case notifications and issued instructions to improve camp conditions and mosquito breeding site control within a deadline - meaning extra work and time diverted from the build.
Together, the project fell 12 days behind programme. Because the contract carries daily delay penalties, the cost showed up very clearly in the monthly report.
Prasert says what changed his thinking was not the penalty. It was walking into one of the shared bedrooms at eight in the evening and seeing six men sleeping in a room with two torn window screens, a container of standing water under the laundry area five metres away, and one of them coughing.
He says: I can pay a penalty. I could not explain it to his family if something happened.
The damage nobody puts on the invoice
Construction worker camps have characteristics that make them a risk point for mosquito-borne disease and respiratory transmission at the same time.
1. A construction site breeds mosquitoes by design
Building work unintentionally creates a dozen kinds of water-holding container: settling ponds, mixing tanks, pile holes, formwork channels, old tyres, paint drums, stacked pipe, and truck tyre ruts that pool.
Aedes mosquitoes, the dengue vector, lay eggs in relatively clean standing water - exactly what rainwater in these containers provides.
Thailand's Department of Disease Control reports every year that the rainy season is the dengue peak, and construction sites are explicitly identified among the high-risk settings.
2. Dense accommodation with limited ventilation
Shared bedrooms holding six to eight people mean shared air all night in an enclosed space - conditions strongly favourable to respiratory transmission.
When one worker has influenza or tuberculosis, spread within the room is rapid. And because workers are also on the same crews during the day, the transmission path is shorter still.
Twelve shared bathrooms for 210 people, plus a shared laundry yard, are the most heavily used shared contact points in the camp.
3. Delay costs multiplied by daily penalties
In a construction contract, delay does not mean simply finishing late. It means a daily penalty accruing until handover.
More awkwardly, construction is sequential. When one crew is short, the next crew cannot start, so a delay propagates through the whole programme.
Prasert calculated that the 12 days lost cost several times what a full year of preventive measures would have.
4. A duty of care to people far from home
Many construction workers come from other provinces or neighbouring countries, far from family and with limited support networks when they fall ill.
Many hesitate to report symptoms for fear of losing daily wages, which delays detection and allows transmission before anyone knows.
For a contractor this is not only labour law and safety compliance. It is a basic responsibility to people who came to work for you.
Why the usual fixes keep failing
After the outbreak, Prasert's team did everything a contractor normally does, and found it helped - but left a gap they could not close.
- Walking the site and tipping out standing water is essential and genuinely effective, but on a site that changes daily, new containers appear daily too. A weekly survey cannot keep up.
- Larvicide granules handle larvae in containers you can treat, but do nothing about adult mosquitoes flying in from surrounding land - and adults are what actually bite people.
- Hiring municipal or private thermal fogging crews works occasionally, requires advance booking, and thermal fogging cannot be used in occupied accommodation. Everyone has to be evacuated and wait.
- Repairing window screens is very necessary, but screens in temporary buildings fail quickly under heavy use, and repairing all 34 rooms takes time and budget that usually sits low on the priority list.
- Handing out repellent helps during the day, but most people do not apply it before sleeping - and the heaviest biting period is early evening around the accommodation.
- Routine cleaning of shared bathrooms and the canteen reaches only visible surfaces, while the 34 shared bedrooms are almost never disinfected at all because they are the workers' private space.
What the professionals reach for — Airofog U260
What Prasert needed was one tool that could do two jobs: control adult mosquitoes across the camp area, and disinfect the shared bedrooms and bathrooms - performed in-house every week, without waiting for an external crew.
ULV - Ultra Low Volume - fogging does both, because the micron-scale droplets suspended in the air are what adult mosquitoes encounter and what settles onto surfaces, depending on the product selected for each task.
The Airofog U260 is a German-built ULV fogger producing 15-30 micron droplets - the range area mosquito control actually requires: small enough to remain airborne long enough for mosquitoes to fly through, but not so small that it disperses immediately on the breeze.
A key advantage of ULV over conventional thermal fogging in a worker camp is that ULV creates no dense smoke and uses no heat. It can be used in and around occupied accommodation more safely, requires much less waiting time, and does not have neighbours calling to ask whether the site is on fire.
10 reasons the Airofog U260 actually solves this
1One machine covers both mosquito control and disinfection
A worker camp has two problems at once: adult mosquitoes around the buildings and respiratory pathogens in the shared bedrooms. One machine that changes chemistry to handle both means the contractor invests once and trains one team.
2Safer than thermal fogging in and around occupied accommodation
Thermal foggers use heat and produce dense smoke, a serious constraint in an occupied camp surrounded by combustible material. The U260's cold ULV output creates no dense smoke and is far more flexible around living quarters.
3It covers all 34 shared bedrooms in a single round
Shared bedrooms are the space that never gets disinfected in most camps. With the U260's speed, a two-person team can treat all 34 rooms in about an hour and a half during the day while the workers are on site.
415-30 micron droplets suit area mosquito control
Droplet size decides the outcome in mosquito work. Too large and the droplets fall before a mosquito can encounter them; too small and they disperse on the wind. The U260's 15-30 micron output sits in the range area control requires.
5You control the schedule, with no waiting for a contractor
Waiting for a municipal or private crew means waiting in a queue, and in the rainy season when everyone wants one, that queue can run weeks. Owning the machine means treating immediately after the first reported case - which is the moment that matters most.
63.4 kg covers the whole site and the camp's upper floor
Worker camps are two-storey buildings with narrow stairs, and site ground is uneven. A machine that is too heavy means the assigned worker does not finish the round. At 3.4 kg the problem disappears.
7A 5-litre tank covers a lot of ground per refill
Sites involve long walks between areas, and the refill point is usually the single site office. The round 5-litre tank significantly reduces the number of return trips.
8Six nozzle settings for outdoor and indoor work
Perimeter mosquito work needs a heavier output; disinfecting bedrooms and bathrooms needs a lighter, faster-drying one. Six settings mean one machine serves both tasks.
9Documentation for health inspectors and the client
When the health authority visits or the project owner asks for a measures report, the Airofog U260 carries certification from Thailand's Department of Medical Sciences, Department of Health and the Faculty of Medicine at Mahidol University, plus WHO, TUV Rheinland and IPARC.
10It moves to the next project with you
Unlike site improvements, which stay behind, a fogger is an asset that travels with the team. Contractors running back-to-back projects reuse the same machine, so the cost per project keeps falling.
Before vs after the Airofog U260
Prasert says the number he took to the board is the last row, because in contracting everything converts into days, and days convert into money immediately.
A practical 7-step rollout plan
Contractors who get this right make it part of the weekly safety routine rather than something done once people are already ill.
Step 1: Put standing water checks on the daily safety checklist
Add water-holding container checks to the daily safety walk you already do, listing the recurring spots - settling ponds, mixing tanks, tyres, formwork. A site changes daily, so a weekly survey is not enough.
Step 2: Separate the mosquito task from the disinfection task
Set perimeter and camp-surrounds mosquito passes at dusk twice a week in the rainy season, and a bedroom and bathroom disinfection pass once a week during the day, with the appropriate product for each.
Step 3: Treat bedrooms while the workers are on site
The best window is between 9am and 3pm while the crews are working. Give advance notice and ask residents to tidy belongings and bedding beforehand.
Step 4: Always pair fogging with screen repairs
Fogging reduces the mosquitoes present, but torn screens let new ones straight back in. Inspect and repair screens in every room monthly, and log it alongside the fogging record.
Step 5: Communicate in the languages your workers actually use
Many camps have workers of several nationalities. Post notices in the languages spoken, explaining when treatment happens, what to prepare, and why reporting a fever matters - with an explicit assurance that reporting does not affect pay.
Step 6: Keep records ready for the health authority
Log date, area, chemical and dilution, operator, and reported case numbers, filed with your project safety documentation so it can be produced at inspection.
Step 7: Review monthly with your safety officer
Bring sick-day figures to the monthly safety meeting, because that number connects directly to programme progress.
Airofog U260 full specification
For worker camp use, the two most important specifications are the 15-30 micron droplet size, suited to area mosquito control, and the 3.4 kg weight, which makes covering the whole site and the camp's upper floor realistic.
From a real user
“I have been in construction for twenty years and I always treated mosquitoes as the municipality's problem. When it happened on my own site, I understood it is the contractor's problem, because the breeding sites are on my land.”
“What I like is that it is not a thermal fogger. We once hired a smoke fogging crew and had to evacuate the camp for half a day, and the neighbours rang to ask if there was a fire. This one produces a cold fog with no dense smoke, and it is far quicker.”
“We now treat around the camp twice a week in the rainy season and the bedrooms once a week. Last rainy season we had no dengue cases on site at all - and we have moved the machine on to the new project.”
— Project manager, high-rise construction, Greater Bangkok (name withheld)
The breeding sites are on your land, which makes controlling them your job too.
See the Airofog U260 price and details - click here
Free consultation: 065-556-6294 | LINE @whd268
The World Health Disinfection team is happy to advise you before you decide, at no cost, and can prepare a quotation and the documents your procurement process needs.
Frequently asked questions
How is this different from a thermal fogger?
A thermal fogger uses heat to create dense smoke, with limitations on visibility, fire safety, and a long evacuation period. The Airofog U260 is a cold ULV system producing 15-30 micron droplets with no heat and no dense smoke, so it can be used in and around accommodation far more flexibly and with much less waiting.
Can bedrooms be treated while workers are inside?
No. Treat during the day while the crews are on site, with advance notice and belongings tidied. Rooms can typically be reoccupied about 30 minutes after the pass, depending on the product and ventilation.
How long do 34 shared bedrooms take?
In practice a two-person team takes about an hour and a half for all the bedrooms plus the shared bathrooms and laundry yard, which fits into the daytime window.
Do you use different products for mosquitoes and for disinfection?
Yes. Mosquito control uses a properly registered insecticide product; accommodation disinfection uses a disinfectant. Flush the tank and system thoroughly when changing between them. The team can advise on the correct procedure and suitable products.
Does the operator need special qualifications?
Basic operation is learned in half a day, but for insect control work the operator should be trained in safe use of insecticide products and wear the full personal protective equipment specified on the product label.
Is it worthwhile on a small project with a few dozen workers?
Yes, because delay costs are charged daily regardless of project size, and the machine moves on to the next project, so the cost per project keeps falling.
Read next / related links
Read next / related links
- All ULV disinfection foggers
- Chemgene HLD4H disinfectant
- Professional disinfection service
- Certificates and test reports
Authoritative references
Related search terms: worker camp mosquito control, construction site disinfection, ULV fogger, Airofog U260, dengue prevention on site, labour accommodation hygiene, cold fogging machine, site safety equipment
See full details and pricing for the Airofog U260 ULV fogger from Germany - click here
