What Is a ULV Cold Fogger and How Is It Different From a Thermal Fogging Machine? A Plain-Language Guide for Everyone in Your Agency

In the same office, one person says "thermal fogging," another says "ULV spraying," and the executive just calls it "mosquito spraying." This guide explains the ULV cold fogger and the thermal fogging machine in simple language, so everyone from executives and procurement officers to teachers, nurses and village health volunteers understands the same thing and knows when to use which mosquito sprayer or mosquito fogger. We use the AIROFOG U240, a German-made ULV unit, as the example.

1-Minute Summary

• What ULV means: Ultra Low Volume. A small amount of liquid is broken into fine droplets that float in the air, without heat. That is why it is often called "cold fogging."
• What thermal fogging means: The machine uses heat to turn the liquid into a thick, clearly visible white fog. It suits outdoor and semi-open areas.
• Key differences: whether heat is used, how visible the fog is, and whether the job is indoors or outdoors.
• What they share: Both are space sprays aimed at adult mosquitoes that are flying or resting. Neither kills larvae, and both must go together with the "3 Keeps, Prevent 3 Diseases" approach as part of wider vector control.
• Example ULV unit: AIROFOG U240 from Germany, 15-30 micron droplets, water-based and oil-based chemicals, fire- and UV-resistant body, 5 L tank, 3.1 kg.
• 3 next steps: Call 065-556-6294 or LINE @whd268 for a quotation and specification, request a demonstration or training, then budget and buy according to regulations.

One Meeting, Three Different Understandings (Illustrative Scenario)

Maleerat is a public health officer who has just transferred to a town municipality in northern Thailand. In her first week, two pupils at a municipal school fall ill with dengue. The principal calls to ask for "the smoke machine to fog every classroom," because parents in the school LINE group are already asking what the school has done.

At an urgent municipal meeting, the head of education believes "the more smoke the better." The procurement officer asks, "The ULV machine a supplier offered last year, that's just a thermal fogger, right?" The deputy mayor worries that children will breathe in smoke in the classroom and that the rooms will smell for days.

Maleerat realises that nobody is careless. Everyone is simply using the same words for different things. Some think thermal fog and ULV mist are identical. Some think ULV means spraying without chemicals. Some believe one spraying keeps mosquitoes away for the whole term. When understanding differs, decisions about equipment, timing and communication with parents all become risky.

She proposes that before anyone decides on machines or budgets, the team should share the same basic understanding. This article is the kind of briefing an agency can use to do that, with no science background required.

Why Misunderstanding Fogging Equipment Matters

Health

The Aedes mosquito carries dengue, chikungunya and Zika. The Aedes aegypti mosquito likes to rest in dark, sheltered places indoors: under desks, behind cupboards and curtains, and in corners. Dengue brings high fever, headache and body aches, and some cases become severe. Schoolchildren, older adults, hospital patients and pregnant women need particular protection. If the wrong type of machine is used indoors, the chemical may never reach resting mosquitoes, and the risk stays exactly where it was.

Budget

Buying a machine that does not match the agency's main task, for example an outdoor unit for mostly indoor work, leads to extra purchases later or more chemical than necessary.

Image and trust

Parents and residents do not see technical details; they see results. Sticky residue on desks, a strong lingering smell, or mosquitoes still flying after spraying all erode trust in the agency.

Complaints

A photo of thick fog inside a school building can be shared with questions about children's safety. Even if procedures were followed, an agency that cannot explain what it used, why, and how it was safe will face complaints.

Staff workload

Staff who do not understand the difference between machines end up experimenting, spraying repeatedly, or cleaning residue afterwards, all of which adds work for no benefit.

Key Terms, One Line Each

How a ULV Cold Fogger Works

Picture a plant-misting spray bottle. Squeeze hard and you get big drops that fall straight to the floor. Make the drops small enough and they float in the air much longer. A ULV cold fogger is designed to do this in a controlled way: it breaks a small volume of liquid into small, consistent droplets without using heat.

Droplet size matters because space spraying depends on droplets touching mosquitoes that are flying or resting:

• Too large: droplets fall quickly onto floors, desks and surfaces, miss flying mosquitoes, leave residue and waste chemical.
• Right size: droplets hang long enough to spread through the room and reach sheltered corners where mosquitoes rest.
• Too small: droplets may drift away on air currents before reaching the target.

Good ULV machines therefore state their droplet range clearly. The AIROFOG U240, for example, produces droplets of roughly 15-30 microns, the range its manufacturer specifies for precise insect control work. Real results still depend on the chemical, the output rate and correct adjustment according to the manual.

A common misunderstanding is that "ULV uses no chemicals." In fact ULV uses insecticide products too, but in a smaller amount per area and with more even distribution. Users must still choose properly registered products, mix according to the label, and wear personal protective equipment every time.

How a Thermal Fogging Machine Works

A thermal fogger uses heat from combustion inside the machine to vaporise the liquid, which then condenses into a fine white fog that is easy to see. Thermal fog penetrates shrubs, the space under raised houses, drains and cluttered areas well, and residents can clearly see that spraying has happened. That is why local agencies know it well for community and outdoor work.

Points to watch: parts become hot during operation, flammable materials must be avoided, thick fog can reduce road visibility, and any use in enclosed spaces must strictly follow the manual and precautions. For these reasons, many agencies choose ULV for classrooms, offices and wards.

An example thermal fogger in the WHD range is the AIROFOG AT35, with a 100% stainless steel body, lightweight design, and compatibility with water-based and oil-based chemicals.

Side by Side: ULV vs Thermal Fogging

The simple conclusion: neither is better in every case. Thermal fogging excels outdoors; ULV excels indoors and where precision matters. Agencies that look after both communities and buildings, such as municipalities with roads and their own schools, often keep both types for different jobs.

5 Common Myths in Agencies

1. "More smoke means better results." Reality: effectiveness depends on droplets reaching mosquitoes, correct chemical use and timing, not on visible smoke.
2. "ULV uses no chemicals." Reality: ULV uses insecticides too, just in smaller amounts with better distribution.
3. "One spraying clears mosquitoes for a month." Reality: space sprays act briefly; new mosquitoes emerge from remaining larvae, so breeding sites must be removed as well.
4. "Any time of day is fine." Reality: spray when mosquitoes are active, generally early morning and early evening. Indoors, spray when buildings are empty and wait before re-entry as the label advises.
5. "All machines are the same." Reality: droplet size, body materials and after-sales service vary widely and affect both results and service life.

Why the Usual Indoor Approach Falls Short

• Using an outdoor machine indoors: thick fog and lingering smell, long closures, and worried building users.
• Worn nozzles and large droplets: chemical lands on desks and floors as sticky residue, while mosquitoes under desks and behind cupboards survive.
• Wrong timing: spraying at midday when mosquitoes are hidden where droplets cannot reach.
• Cheap, non-standard machines: no stated droplet size, fragile bodies, hard-to-find parts.
• No after-sales support: a mid-term breakdown with long repair waits during a case cluster.
• No explanation to parents or users: unnecessary worry and complaints.

What Each Person in the Agency Should Know

Mosquito spraying is not only the fogging team's business. Each role needs a different piece of the picture. In short:

When everyone knows their part, a single spraying achieves its full effect, wastes no trip and causes no unnecessary worry. Executives can even attach this table to a work assignment order during an outbreak, so every division knows what is expected of it from day one.

The Indoor Solution: AIROFOG U240 ULV Cold Fogger

Once you understand that indoor work needs well-sized droplets, no heat and good control, the AIROFOG U240 ULV cold fogger from World Health Disinfection Co., Ltd. (WHD) is an example that fits. According to its product page:

WHD also holds ISO and GMP systems, performs 100% quality checks before delivery, and provides technicians, spare parts and full after-sales service, with equipment that meets Thai government equipment standards. This makes the U240 a good fit for schools, child development centers, offices and clinics run by public agencies.

Other options in the same group include the AIROFOG U260 with an 800 W motor and adjustable nozzle, and the cordless AIROFOG AIROSTAR for places without power outlets.

10 Reasons the AIROFOG U240 Makes a Good Agency ULV Unit

1. 15-30 micron droplets: sized to hang in rooms and reach resting corners.
2. No heat: better suited to indoor work than machines with a hot combustion chamber.
3. Only 3.1 kg: trained teachers, staff or volunteers can carry it without strain.
4. 5 L tank: fewer refills, continuous work through a building.
5. Water-based and oil-based chemicals: flexible for different areas and situations.
6. Fire- and UV-resistant body: less risk of damage in use and storage.
7. Made in Germany: clear origin information for procurement files.
8. Less surface residue when well adjusted: rooms return to use sooner, within label re-entry times.
9. Multi-purpose: beyond Aedes, supports control of other insects covered by the product label, such as flies and cockroaches indoors.
10. WHD technicians and parts: see details and request a quotation on the AIROFOG U240 product page.

Before and After a Shared Understanding

Procurement Tips: A ULV Specification Everyone Can Understand

1. Name the type in the item title

Write "ULV cold fogger" rather than just "mosquito sprayer," so bidders do not mix in other machine types.

2. Ask for droplet range and chemical compatibility

Require the droplet range in microns and compatible chemical types, backed by manufacturer documents. Write it so several models can bid, keeping competition fair.

3. Include tank capacity, weight and materials

These determine how easy the machine is for staff and how long it will last.

4. Specify after-sales and training

Ask for warranty, service channels, parts and operator training covering adjustment, label-based mixing and cleaning.

5. Budget for what goes with it

Plan for registered chemicals, personal protective equipment and maintenance under the relevant budget lines.

6. Attach a short explainer to the memo

Use the comparison table in this article so executives and council members see why this type is needed. Follow your agency's procurement regulations throughout.

Safe Indoor ULV Spraying: An Overview

1. Schedule spraying when the building is empty, such as after school or at weekends, and notify people in advance.
2. Store or cover food, drinking water and learning materials, and remove pets.
3. Switch off fans and air conditioning during spraying, as the product advises.
4. Mix according to the label and wear a mask, gloves and eye protection.
5. Start at the far end of the room and work back towards the door, focusing on under desks, behind cupboards and dark corners.
6. Keep the room closed for the time on the label, then ventilate before re-entry.
7. Clean the machine according to the manual and log the treated areas.
8. In the same week, survey and remove standing water around the building with teachers and pupils.

Explaining It to Parents and Residents

Because ULV mist is hard to see, people may assume nothing was done. A short, honest message prevents that. Here is a sample notice a school or municipality can adapt for its LINE group or notice board:

Notice what the message does: it says what was done and why, explains why the mist is hard to see, sets expectations honestly, and gives every family a practical role. That is often the difference between a complaint and a thank-you.

Example Field Perspective

"Once we handed out a one-page comparison of ULV and thermal fogging at the meeting, everyone was on the same page within ten minutes. The executives saw for themselves why classrooms should use ULV while community work still uses thermal fog. Teachers are happier because desks are no longer sticky, and we can tell parents exactly what we sprayed, when, and how it was kept safe."

This is a composite example based on the typical work of local public health and school staff, not a statement by any specific person or agency.

3 Next Steps

1. Call or LINE for a quotation and specification: Call 065-556-6294 or LINE @whd268 for AIROFOG U240 details and advice on whether your work needs ULV, thermal fogging, or both.
2. Request a demonstration or training: Let teachers, staff and volunteers see the difference with their own eyes.
3. Budget and buy according to regulations: Attach the comparison table to your proposal memo.

Frequently Asked Questions

Q: Can a ULV sprayer and a thermal fogger replace each other?
A: Sometimes, partly. But each has its own strengths: thermal fog for outdoors, ULV for indoors and precision work. Matching the machine to the job gives better results.

Q: ULV mist is hard to see. Does it really work?
A: ULV droplets are small and not heat-generated, so they do not form thick white smoke. Being less visible does not mean less effective. Droplet size, correct chemical and thorough coverage of resting sites are what count.

Q: Is ULV safer than thermal fogging?
A: Both use insecticides. Safety depends on registered products, label-based mixing, spraying unoccupied spaces and wearing protection. ULV's indoor advantage is that it uses no heat and a small volume of chemical.

Q: Which chemicals can the AIROFOG U240 use?
A: Its product page lists both water-based and oil-based chemicals. Choose properly registered products and follow the label every time.

Q: How often should we spray?
A: It depends on the disease situation and local public health advice. Space sprays act briefly, so plan them alongside regular larval surveys and removal.

Q: Which type should a small agency buy first?
A: Look at the main task. For mostly buildings such as schools or child development centers, ULV is usually the better fit; for mostly communities, a thermal fogger often is. The WHD team can advise based on your actual area.

Q: Can ULV machines be used for disinfection?
A: Many ULV machines can apply disinfectant products when the product label allows fogging use. Check the label and ask the supplier before use.

Now Everyone Understands, Choose the Right Machine

AIROFOG U240 ULV cold fogger from Germany, 15-30 micron droplets, for indoor spraying in public agencies.

View AIROFOG U240 Products and Prices - Click Here

Call 065-556-6294 | LINE @whd268

Email worldhealthdisinfection@gmail.com

Visit the Government Mosquito Control Equipment Center

World Health Disinfection Co., Ltd., 88 268 Kanlapaphruek Road, Bang Khae, Bangkok 10160

Related Links

• WHD Mosquito and Insect Control Equipment Center for Government Buyers
• AIROFOG AT35 Thermal Fogging Machine
• AIROFOG U260 ULV Cold Fogger
• Department of Disease Control, Ministry of Public Health (Thailand)
• World Health Organization: Dengue and severe dengue fact sheet