Electronics Factory with a Class 100,000 Cleanroom: 58 Staff Ill, Four Days of Stopped Lines, and Missed Shipments to a Japanese Customer
Last updated: 6 Sep 2026 | 16 Views |
COVID-19 disinfection sprayer 2026 for factories, cleanrooms and staff facilities
Electronics Factory with a Class 100,000 Cleanroom: 58 Staff Ill, Four Days of Stopped Lines, and Missed Shipments to a Japanese Customer
Why the best-filtered room in the factory still cannot stop what moves between people.
A cleanroom is designed to keep dust off the product, not to keep infection away from people. Two hundred and forty staff in cleanroom suits stand close together in a room filtered to 0.5 microns — that recirculates the same air all shift. This is what happened at one factory in an industrial estate.
A cleanroom has the best air filtration in any factory, but that system was designed around one question — how to keep dust off the product — not around how to stop what one person exhales from reaching another.
Most plant managers follow their measures strictly: screening at the gate, equipment wiped, floors cleaned on schedule, cleanroom garments laundered to standard. All correct, and all of it surface work and dust control — while the canteen and the changing room, where two hundred and forty people gather at once, have never had their air managed at all.
What follows is the whole story: the first shift, the four days of stopped lines and the missed shipments, and the change that stopped it. At the centre of it is the AIROFOG U260 ULV cold fogger, a German-engineered machine producing 15-30 micron droplets.
The story
The cleanest factory in the estate
Wanna is production manager at an electronics assembly plant in an industrial estate, with two hundred and forty production staff per shift across two shifts, and a Class 100,000 cleanroom for the main assembly line.
The plant passes its Japanese customer's audit every year and has always scored highly on cleanliness. The cleanroom's filtration handles particles down to 0.5 microns, floors are cleaned every two hours, and everyone wears a full cleanroom suit and mask in the production area.
But staff are not in the cleanroom all day. They change in a sixty-square-metre changing room that eighty people enter at once at shift change, eat in a canteen where two hundred people sit at midday, and ride to work together on staff buses morning and evening.
In all three of those areas nobody wears a mask, there is no special filtration, and there is no air management of any kind.
Eleven days, 58 people, and the lines stopped
It began with two morning-shift workers who came in unwell. Both rode the same staff bus and habitually ate at the same canteen table.
Day four: fourteen absences. Day seven: thirty-one. Day eleven: fifty-eight out of two hundred and forty.
When Wanna plotted the data, the ill workers were not clustered by production line inside the cleanroom. They clustered by staff bus and by canteen table — the two places where masks come off.
Down twenty-four per cent of the workforce, two main lines could not run at all. The plant stopped those lines for four days to concentrate people on the line with the most urgent orders.
Missed shipments and a special customer audit
Four days of stopped lines meant two lots shipped late. The Japanese customer, an automotive component maker, had to adjust its own production plan.
In this industry, a late shipment does not end with a penalty. It triggers a special audit: the customer sent a team to review the process and required a written recurrence-prevention plan within thirty days.
Wanna says writing that plan was what made the problem clearest. The plant had hundreds of pages documenting dust control in the cleanroom, and not one page about air management in the canteen, the changing room or the staff buses.
The total cost of the incident — overtime to catch up, air freight instead of sea for the late lots, and the audit process itself — came to about 1,300,000 baht.
What the food plant next door had been doing for years
Wanna spoke to the manager of a food processing plant in the same estate and found they had been fogging their changing rooms, canteen and staff rest areas at every shift change for years.
Their reason was that food safety standards require management of areas where people contact food, which meant they already had fogging equipment — and they simply extended it to the staff areas, because it was the same machine.
That was the difference. The electronics plant had invested enormously in dust control inside the production area, and nothing at all in the places where people take their masks off together. The food plant had both, because a standard required it.
What the plant needed was a machine that could fog a two-hundred-seat canteen, a sixty-square-metre changing room and the staff buses, during shift changes, without disrupting the lines or damaging equipment.
What it actually costs
Down 24 per cent and the lines cannot run at all
An electronics line needs every station staffed to run. Losing twenty-four per cent of the workforce does not mean producing twenty-four per cent less — it means some lines cannot run at all.
A late shipment triggers a special customer audit
In component manufacturing, missing a shipment brings a customer audit team and a written recurrence-prevention plan requirement — a burden far heavier than any penalty.
Hundreds of pages on dust, not one on the air people breathe
Writing the recurrence-prevention plan revealed that the plant had no documentation at all about air management in the canteen, changing room or staff buses — the places the problem actually happened.
Catching up costs several times normal production
Overtime, air freight instead of sea freight, and the audit process together came to about 1,300,000 baht, none of which existed anywhere in the production budget.
Why the usual fixes fail
The cleanroom filtration system
Cleanroom filtration handles very fine particles and does its job superbly. But its job is keeping dust off the product, and it exists only in the production area — not in the canteen, the changing room or the staff buses.
Temperature screening at the gate
Gate screening catches only people who already have a fever, not those just beginning to feel unwell — and in a plant where pay or bonuses are tied to attendance, some people will take a fever reducer before arriving.
Requiring masks at all times
Staff already wear masks in production as standard. But they must remove them to eat in the canteen, to change in the changing room, and many take them off on a long bus ride. The places where you cannot enforce it are exactly where the problem happened.
Staggering lunch breaks
Staggering does genuinely reduce canteen crowding, but in a sealed room with no air exchange the second sitting still gets the first sitting's air — and staggering complicates the line schedule as well.
Deep cleaning at the annual shutdown
An annual shutdown clean makes the plant spotless for that period, and the first shift back puts everything in place again. It is dust and grime management, not air management during use.
What the areas outside the cleanroom actually need
The requirement is not finer filtration in the production area. It is a treatment aimed at the volume of air in the places where people take their masks off together: the canteen, the changing room and the staff buses.
That is exactly what ULV cold fogging is designed for. ULV, ultra-low volume, means the machine breaks disinfectant into droplets fine enough that the output behaves more like fog than spray. The mist stays airborne long enough to fill the room, then settles evenly on every surface.
The machine Wanna's plant chose is the AIROFOG U260: a German-engineered ULV cold fogger with an 800-watt motor and an adjustable nozzle producing 15-30 micron droplets, running on water plus the disinfectant the plant has approved.
10 reasons the AIROFOG U260 solves it
1. It treats the places masks actually come off, which is where the problem is
The plant's own data showed the ill workers clustered by staff bus and canteen table, not by production line. Fogging those three areas addresses the cause instead of adding measures to a room that was already safe.
2. 15-30 micron droplets cover a 200-seat canteen
A canteen has tables, chairs, counters and a ceiling that table-wiping never reaches. Droplets in this range fill the room's volume and settle across every surface in one pass.
3. It runs during shift changes without stopping the lines
The canteen is empty between sittings, the changing room is empty once shift change is done, and the staff buses stand idle between runs. All three have their own empty windows already — the lines never stop for a minute.
4. An 800-watt motor covers the canteen and changing room
One machine covers a two-hundred-seat canteen, a sixty-square-metre changing room, the bathrooms, the first aid room and every staff bus. The plant does not need multiple units.
5. The adjustable nozzle is safe in areas with electrical equipment
Changing rooms have lockers and air showers; canteens have chillers and food warmers. A drier nozzle setting lets you fog these spaces without damaging any of it.
6. It runs on disinfectant the plant has already approved
The U260 is a delivery system, not a chemical lock-in. The plant can immediately use the product that already passed its own safety and environmental approval process.
7. Floors dry fast, so shift start times are unaffected
Cold fogging at this droplet size leaves a very thin, fast-drying film. The changing room and canteen are ready on the original schedule, and floors are not slippery for people moving quickly.
8. Shift leaders and the facilities team can run it
No contractor every shift. The plant's facilities team fills and fogs itself, learning it in an afternoon, and it happens every shift rather than occasionally.
9. It is the same class of equipment hospitals use
The U260 was designed for COVID-19 disinfection and is used in hospital and laboratory settings. For a plant submitting documentation for customer audit, that is provenance a Japanese customer accepts.
10. It becomes a recurrence-prevention plan you can actually submit
A plant that fogs every shift has an auditable per-area, per-shift log — documentation that goes straight into a recurrence-prevention plan, and exactly what a customer audit team looks for.
Before and after
Before
- Heavy investment in cleanroom filtration, and nothing outside the production area
- A 200-seat canteen, a 60 sqm changing room and staff buses with no air management at all
- 58 of 240 staff ill within 11 days
- Ill workers clustered by staff bus and canteen table, not by production line
- Lines stopped for 4 days, 2 lots shipped late, and a special audit by the Japanese customer
- Total cost around 1,300,000 baht in overtime, air freight and audit process
After
- ULV fogging of the canteen, changing room and bathrooms at every shift change
- Every staff bus fogged between the morning and evening runs
- Not one minute of production line time lost
- No further simultaneous illness cluster in the following year
- A per-area, per-shift disinfection log used as documentation in the recurrence-prevention plan
- Passed the customer's next special audit with no findings on this point
How we get you started, in 3 steps
1. Find the places where people take their masks off together
The canteen and how many people per sitting, the changing room and how many at shift change, the staff buses and how many per run, the first aid room, and the meeting rooms. Those five are what to treat first. Send us the plant layout and we will identify them.
2. Install the machine and train the facilities team
We deliver the U260 with the nozzle set dry enough for areas with lockers, chillers and electrical equipment, the correct dilution for your approved disinfectant, and a route that finishes inside your real shift change window. Training takes an afternoon.
3. Fit it into the shift change procedure and document it
The routine that works is boring and repeatable: fog the canteen after every sitting, the changing room after every shift change, and the buses between runs — logging the time each time. Once it is on the shift change checklist it becomes documentation you can hand to a customer.
What a customer says
“Writing the recurrence-prevention plan for our Japanese customer was what showed me the gap. We had hundreds of pages on dust control in the cleanroom and not one page about the air in the canteen or the staff buses — which is exactly where the ill workers clustered. We now fog those three areas every shift, with a log every time, and we passed the next audit with no findings on this point.”
Wanna — Production manager, electronics factory, industrial estate, Thailand
Why the cleanroom does not help with this
A cleanroom is classified by particle count per volume of air. Class 100,000 means no more than one hundred thousand particles of 0.5 microns or larger per cubic foot — a standard designed to protect the product from dust.
That system does its job extremely well. But its job is to make the air clean enough for the product, not safe enough for people breathing together for eight hours — and in many systems most of the air is recirculated rather than fully replaced.
More importantly, staff are not in the cleanroom the whole time. They spend two to three hours a day in the changing room, the canteen, the bathrooms and the staff bus, and none of those areas has any special filtration at all.
This is why the cleanest factory in an estate can still have this problem. Not because the system is poor, but because the system was designed to answer a different question from the one that actually arose.
What 15 to 30 microns actually means in practice
Droplet size is the specification that decides whether a machine solves this problem or merely makes things wet. Below roughly 10 microns, droplets are so light they can drift away before doing useful work. Above about 50 microns they behave like spray: they fall fast and leave floors wet enough to be slippery.
The 15-30 micron band is the working range. Droplets stay airborne long enough to fill a two-hundred-seat canteen's volume and reach the ceiling and vents, then settle as a thin, even, fast-drying film. Areas are ready on the original schedule.
It is also why an adjustable nozzle matters more than tank size. A changing room with air showers and powered lockers needs a drier setting than a tiled canteen, and a staff bus with fabric seats drier still.
For a factory the practical test is simple: after a pass the floor should be walkable within minutes and not slippery, lockers and air showers should show no water, and the canteen ceiling corners should genuinely have been treated.
Frequently asked questions
Do we need to fog inside the cleanroom too?
Generally not. Staff already wear masks and full suits in the production area, and introducing a solution into a cleanroom requires assessment of the effect on the product. We recommend starting with the canteen, changing room and staff buses, which is where the problem actually occurs.
How long does a 200-seat canteen take?
Only a few minutes to fog, plus a closed-room period depending on the solution used — which fits between sittings or after the canteen closes.
Do the production lines have to stop?
No. The canteen, changing room and staff buses all have their own empty windows in the normal shift schedule. All fogging happens in those windows.
Will lockers, air showers and chillers be damaged?
No, with the nozzle set dry enough and equipment switched off during the pass. We build this into a checklist for the facilities team at installation.
Can it be used on the staff buses too?
Yes, and it should be. Data from many plants shows the staff bus is where ill workers cluster most tightly, and fogging one vehicle takes only a few minutes.
What disinfectant works with the U260?
The machine runs on water plus the solution you choose. It is not tied to one brand, so most plants use the product that already passed their own safety and environmental approval. We work out the correct dilution.
How often should a factory fog?
The canteen after every sitting, the changing room after every shift change, and the staff buses between the morning and evening runs. Consistency matters far more than intensity.
Can the fogging log really be submitted for customer audit?
Yes. We provide a per-area, per-shift log format at installation, in a documentation style industrial customer audit teams accept.
The problem is not in the room you already invested in — it is in the room you never looked at
Wanna's plant took about 1,300,000 baht of damage, stopped its lines for four days and faced a special customer audit — all from areas that had never appeared in any of the plant's control plans.
ULV fogging every shift costs less than a few hours of overtime and stops the lines for exactly zero minutes. It treats where the problem actually happens, and produces documentation you can hand to a customer.
If you run a factory, a plant in an industrial estate, a processing facility or any workplace with a canteen and staff buses, send us the layout and we will help you find what to treat first.
See the AIROFOG U260 ULV cold fogger, specifications, droplet range and price
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