MAC Indicators
MAC indicator
(ang. Maximal Allowable Concentration) is the highest permissible concentration of a given substance. The definition of the indicator refers to the maximum time of exposure to a factor harmful to health during professional activity. In an amount that will not have negative effects on his health and the health of his future generations.
In more understandable language – it is a weighted average, determined on the basis of a 40-hour work week, with 8 hours a day, for a healthy “model” man. The MAC indicator therefore indicates how much of a hazardous substance you can absorb daily without fear of losing your health during 8 hours of work.
MAC-C indicator
(ang. Maximal Allowable Ceiling Concentration) otherwise the highest permissible ceiling concentration. That is, such a value of the concentration of a toxic chemical compound that due to a threat to the health or life of an employee can NEVER be exceeded.
MAC-TGG or MAC-TGW or MAC-STEL indicator
(ang. Maximal Allowable Concentration Short Therm Exposure Limit) otherwise the highest allowable momentary concentration. This is the maximum time of exposure to a toxic chemical compound in its maximum dose defined by the MAC index. In other words, if you are exposed to a toxic substance that has a specific MAC-TGG/TGW/STEL index, you cannot work with that substance longer that day than the MAC-TGG/TGW/STEL index. Even if the dose of the toxic substance is lower than the dose defined by the MAC index.
The MAC, MAC-C and TGG indicator values are given in [mg/m3] (milligrams per cubic meter). The MAC-TGW indicator is additionally given in minutes.
An additional designation for MAC indicators is the letter S, which means that a given hazardous substance easily penetrates the skin – and additional protection (clothing, gloves) should be used.
Since there are many of these abbreviations and they are all used interchangeably, we will present them in a table – it will be easier to understand:
| Name | Abbreviation GHS | Abbreviation NL | Description | Measurement |
|---|---|---|---|---|
| Maximum allowable concentration | TLV-TWA | MAC-TGG | Weighted average concentration of a chemical in the air for 8 hours per day / 40 hours per week or for a designated time period e.g. 6 hours. | mg/m³ |
| Maximum allowable momentary concentration | TLV-STEL | MAC-TGW | The highest permissible concentration of a substance for a short period (e.g. 15 minutes) – cannot be exceeded even for a moment.
|
mg/m³ + (min) |
| Maximum so-called ceiling concentration | C | MAC-C | A concentration that must never be exceeded, even for a moment – it may be immediately dangerous to your health. | mg/m³ |
| MAC general | – | MAC | Generic index used in the Netherlands, means concentration limit of a substance – may refer to MAC-TGG or MAC-TGW depending on the context. When used alone it means the weighted average concentration of a chemical in the air over 8 hours per day / 40 hours per week. | mg/m³ |
| S (skin) – extra letter | S | S | Means that the substance easily penetrates the skin, which should be taken into account when assessing risk. Requires the use of special personal protective equipment. | – |
