Dust class H

What does dust class H mean?

Filters and extraction systems are both classified in dust classes. Consider the preferred degree of separation, which has to be achieved, and the type of dusts, which has to be removed. Filters of class H are particularly effective and work for very small particles like hazardous dusts. The dust classes are divided into three groups, which are L, M and H. For the filter dust classes, L defines coarse-grained, M slightly finer and H the finest dust, while the dust classes regulate the use of the systems:

Dust classes of filter and extraction systems

Usable for


L – slightly hazardous dusts

Common house dust, sand, gypsum, lime, as well as allergenic substances such as mite and pollen


M – medium hazardous dusts

Wood dust, paint particles and various metal dusts

Small companies, for more control and transparency

H – highly hazardous dusts

Suitable for highly dangerous and carcinogenic substances such as mold spores, lead dust, mineral fibers

Companies with hazardous substances, extremely well filtration, highest security

Systems of dust class H must be maintained and checked regularly once a year by the operator in order to not exceed the legally prescribed occupational exposure limits (German Arbeitsplatzgrenzwerte = AGW). In case of additional hazardous dusts, the protection of the employees is based on the measurement of the air velocity in detection elements, hoses and pipes as well as a dust-reduced (Class M) or dust-free (Class H) filter disposal.

Safety vacuum cleaners that comply with dust class H can only draw in asbestos dusts. In Germany, these cleaners must additionally fulfill the requirements of TRGS 519 No. 7.2 par. 6. Special vacuum cleaners are used, which have been particularly approved for explosive and flammable dusts, in accordance with the ATEX directives. Classes L and M may be used for non-carcinogenic dusts with AGW values > 1.0 mg / m³ or flammable dusts for applications in ATEX zone 22.

Since 1998, the international standard DIN EN 60335-2-69 has been used as the base of evaluation for dust-removing machines (SBM) in industrial uses. It defines the intended suitability of the devices and classifies them according to the different testing basics. With the new Hazardous Substances Ordinance, the values of the "Maximum Workplace Concentration" (MAK) were replaced by the AGW limits. DIN EN 60335-2-69 differentiates between dry, unhealthy and flammable dusts and assesses their classifications. The guidelines for ventilation and air conditioning systems (RLT) of July 2011 apply to a system certification.

Dust concentration

EN 60335-2-69, IEC 335-2-69

AGW limit
from 2005

MAK limit
until 2005

Dust class

max transmittance

AGW > 1mg/m³

MAK > 1mg/m³



Dusts and wood dust
AGW > 0,1 mg/m³

Dusts and wood dust
MAK > 0,1 mg/m³



Carcinogenic dusts
AGW < 0,1 mg/m³

Carcinogenic dusts
MAK < 0,1 mg/m³



Highly carcinogenic dusts
AGW < 0,1 mg/m³

Highly carcinogenic dusts
MAK < 0,1 mg/m³



Table of valid norms

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