Measurement Concept & PM Classification

This section explains how AirWatch measures particulate matter (PM2.5 / PM10) and how the displayed load levels are defined and interpreted.

Introduction

Have you ever wondered why the PM2.5/PM10 display in our dashboard does not work 1:1 with legal limits – or why you rarely see “limit exceeded” despite visible welding fumes?

That is exactly the intention.

Our system monitors indoor air: it measures the air at typical locations in the workshop or hall – i.e., where air circulates, where pollution is distributed, and where ventilation/extraction should be effective. It is not a personal measurement system directly on the welder, nor is it a compliance measuring device for the legally compliant assessment of an individual workplace.

That is why we deliberately use exposure levels (guideline values) instead of “limit values.” The goal is not to replace a legal assessment, but to give you a reliable tool to:

• Detect pollution in the hall at an early stage

• Control ventilation/extraction as needed

• Make improvements measurable (before/after, shift comparison)

and all this in a practical way, without being permanently on “red alert.”

In short: We optimize control and transparency in the hall – not the legal assessment of personal exposure.

The Problem

Many customers initially compare the AirWatch PM2.5/PM10 values to legal workplace limit values. That comparison is understandable — but it mixes two different measurement concepts.

Legal workplace limits are defined for personal exposure. In practice, this means they must be measured on the worker, in the breathing zone, using personal sampling equipment and regulated procedures (often based on time-weighted averages). Depending on the regulation, assessments may also require measurements very close to the emission source under defined conditions.

AirWatch is not used that way.

AirWatch is a stationary ambient monitoring device. It is typically placed near work areas or distributed across the hall to measure general hall air conditions, not the exposure of a specific person.

Because of that:

• A high AirWatch reading can be a strong indicator that overall conditions are poor and that exposure at certain workstations could also be elevated.

• But it does not prove that a legal workplace limit has been exceeded - because the legally relevant value depends on what a person actually inhales (distance to the source, duration, airflow, work position, PPE, etc.).

On top of that, workplace limits and evaluation methods are country-specific and depend on local regulations.

For legal compliance checks, dedicated personal measurement solutions exist that are designed and certified for that purpose.

AirWatch is built for a different job: continuous ambient monitoring to detect rising load early, optimize ventilation/extraction, and make improvements measurable — without turning the dashboard into a “legal compliance” statement.

The Solution

Instead of displaying legal limit values, AirWatch uses clearly defined operational load levels for ambient hall air.

These levels are intentionally designed to:

• reflect realistic industrial conditions

• provide early indication of rising particulate load

• support stable and demand-based ventilation/extraction control

• make trends and improvements measurable over time

This approach avoids misleading compliance interpretations while still delivering actionable insight.

In simple terms:

AirWatch does not determine whether a legal workplace limit has been exceeded — it provides continuous transparency about hall air conditions and enables operational optimization.

Details

Dashboard

Values in the dashboard are not intended to check legal limit values in the workplace.

It is deliberately designed as a guide for room or hall air – i.e. for assessing air quality, extraction efficiency, trends, and control logic (e.g., automatically increasing ventilation/extraction), not for occupational health or legal assessments of individual persons.

Why no “limit values”?

In welding and industrial halls, there are two completely different worlds of “values” – and these are often confused in practice:

A) Ambient/environmental guideline values (e.g., WHO) These guideline values are intended for the general population and long-term 24/7 exposure and are therefore very strict. They are not designed as an assessment standard for production halls.

B) Occupational exposure limits (OEL/AGW) These limits refer to personal exposure in the breathing zone (i.e., what a person actually inhales) – typically as an 8-hour time-weighted average and with personal measurement on the employee.

Our measurement in the product is not close to the person and not in the breathing zone. It would therefore be technically incorrect (and communicatively risky) to derive statements such as “limit value complied with/exceeded” from our values.

What our sensor actually measures (measurement context)

Our devices measure stationary hall/room air (ambient) – typically near work areas or distributed throughout the hall for overall monitoring.

This does not answer the question: “Is a single workstation legally within a limit value?”

Rather, it answers this question: “How high is the general fine dust pollution in the hall – and how effective is ventilation/extraction?”

Important: In practice, values directly at the source / in the breathing zone are often significantly higher than values in the room air – simply due to dilution, air flow, and distance.

What the ranges are intended for (purpose of the scale)

Our areas are exposure levels – not limit values. They are intended to:

• Create transparency (What is happening in the hall right now?)

• Make trends visible (before/after, shift comparison, week comparison)

• Evaluate the effectiveness of extraction (extraction off/on/optimized)

• Provide stable thresholds for automation (control ventilation/extraction as needed)

• Consciously avoid making “legal/illegal” statements

In short: Operational optimization instead of legal limit value testing.

Scale is not WHO-compliant

In industrial environments (especially welding halls), ambient particle values often remain permanently above typical environmental guidelines. A scale that is strictly optimized for environmental values would often lead to a permanent “red” status during operation – without this being helpful.

Our scale is therefore chosen so that it:

• reflects real industrial processes (no permanent alarm)

• still responds appropriately to changes (when conditions actually worsen/improve)

• is suitable for control logic (no frantic switching at every short peak)

What the display explicitly does NOT mean

The display does not replace:

• occupational health measurements (close to people / breathing zone)

• the evaluation of individual workplaces

• the legal classification according to OEL/AGW/legal limits

It means:

• Orientation regarding hall air pollution

• Comparability and traceability

• Optimization of extraction and ventilation measures

Practical relevance: Control of ventilation & energy efficiency

A key use case is demand-based control:

• Only increase extraction/ventilation when pollution levels rise

• Step operation depending on level (e.g., “increased” vs. “very high”)

• Reduce again during quiet phases → Save energy, reduce running times, protect equipment

Note on communication (deliberately chosen): We use terms such as “load” / ‘level’ / “guideline values” instead of “limit value” or “healthy/unhealthy” because the product is conceptually a monitoring and optimization tool for indoor air – not a compliance measurement system for personal exposure.