Information on limit values of gases, particles and pollutants in the air we breathe.

Limit values are controversially discussed. For many they are too low, for others too high. However, it is important to know them and even understand the background - e.g. why much higher limit values are often permitted in the workplace than at home or outdoors. We have compiled this information on limit values for gases, particles and pollutants in the air we breathe for you here in an overview.

Limits in view

Where are legal limits for pollutants in the air - find out here. For your health and well-being!

Here you will get an overview of the often complex definition of the limit values of air pollutants such as particulates, nitrogen dioxide, VOC, formaldehyde or ozone, which are specified by the Federal Environment Agency or the WHO. A distinction is made between limit values for specific pollutants outdoors, indoors and at work. In fact, it is often difficult to keep track and find out when action is required. The air analyzer air-Q helps you by monitoring the limit values for you.  
 particulates PM10 PM2.5 PM1 icon
particulates (PM₁ - PM₂,₅ - PM₁₀)
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Limit values
Designationning PM 1 PM 2.5 PM 10
EnvironmentFEDERAL DAyrichtvalue  -            15 µg/m³  -           
EnvironmentFEDERAL DAybordervalue  -             -            50 µg/m³
EnvironmentFEDERAL OFFICE Yearbordervalue  -            25 µg/m³ 40 µg/m³


The Federal Environment Agency specifies a daily limit value of 50 μg/m³ for particulates particles PM10, which may only be exceeded on 35 days a year. In general, a maximum annual mean value of 40 μg/m³ applies. For the smaller particles PM2.5, there are only non-binding target values of 25 μg/m³ set by the EU and WHO. For even smaller particles - although infinitely more dangerous - there are currently no limit values.

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Measure nitrogen dioxide with air-Q icon
Nitrogen dioxide (NO₂)
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Limit values
Designationning EU outdoor airlimit values Workplacelimit values Interiorguidelines
Longtimevalues 40 µg/m³ - 40 µg/m³
Short-termvalues Immissionlimit value 1h-Mean value 200 µg/m³,
AlarmThreshold 3h-Mean value 400 µg/m³
- Beforecarevalue 1h-Mean value 80 µg/m³,
Dangersvalue 1h-Mean value 250 µg/m³
Worklayer - 950 µg/m³ -


The EU specifies a limit value of 200 µg/m³ as the maximum limit for the mean value of an hour. This limit may not be exceeded more than 18 times per year. If a value of 400 μg/m³ is exceeded within three hours, immediate action must be taken. The Federal Environment Agency specifies guideline values for indoor areas - 80 µg/m³ as an hourly average and 40 µg/m³ as an annual average. The short-term alarm value is 250 µg/m³.

The occupational exposure limit (OEL) of NO₂ is set at 950 µg/m³ with numerous exceptions. However, this high value applies in particular to workers who are exposed to increased nitrogen dioxide pollution at their workplace, i.e. who do not work in offices. The Federal Environment Agency recommends - also indoors - setting the maximum weekly mean value at 40 µg/m³.

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Carbon dioxide icon
Carbon dioxide (CO₂)
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Limit values
Designationning Carbon dioxide limits
Recommendation Federal Environment Agency 1,000 ppm
DIN-1946-2 Limit value for good air quality 1,500 ppm
MAK-Value for workplaces 5,000 ppm


The Federal Environment Agency recommends ventilating as soon as a value of 1,000 ppm carbon dioxide is exceeded. The maximum workplace concentration (MAK value) specifies a limit of 5,000 ppm. DIN-1946-2, which is no longer valid, stipulated a limit of 1,500 ppm. In children's rooms, bedrooms and fully occupied classrooms or meeting rooms, values of over 5,000 ppm can be measured quickly.

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Carbon Monoxide Detector Measure icon
Carbon monoxide (CO)
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Limit values
Designationning Carbon monoxide limits
EnvironmentFEDERAL OFFICE 24h-Leitvalue 4 mg/m³ (3.2 ppm)
EnvironmentFEDERAL OFFICE 8h-Leitvalue 10 mg/m³ (8 ppm)
WHO Recommendationling 1h value 25 mg/m³ (20 ppm)
MAK value 35 mg/m³ (28 ppm)
EnvironmentFEDERAL OFFICE LEADvalue 15min 100 mg/m³ (80 ppm)
WHO Recommendationling 15min value 85 mg/m³ (68 ppm)


The Federal Environment Agency specifies a 24-hour average value of 4 mg/m³ for carbon monoxide. The maximum workplace concentration (MAK value) of carbon monoxide is given as 35 mg/m³ - the MAK values do not apply to pregnant women or people with pre-existing conditions. The WHO recommends that values above 25 mg/m³ should not be inhaled for more than one hour, and values up to 85 mg/m³ for a maximum of 15 minutes. The Federal Environment Agency is somewhat less strict here with 100 mg/m³.

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Measure oxygen O₂ icon
Oxygen (O₂)
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Limit values
Designationning Oxygen limits
DGUV Rule 113-004 for work in silos and confined spaces 17 %


There are no legal limits for oxygen in Germany. DGUV Rule 113-004 of the German Social Accident Insurance for Occupational Safety specifies a value of 17 % oxygen. The amount of oxygen still present in exhaled air is 16 %.

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Measure ozone icon
Ozone (O₃)
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Limit values
Designationning Limit values ozone
Environmentfederalamt maximum 8h value 120 µg/m³
EnvironmentfederalOffice Informationsthreshold (1h averageworth) 180 µg/m³
Environmentfederalamt Alarmvalue (1h averageworth) 240 µg/m³


The Federal Environment Agency sets a maximum 8-hour value for ozone of 120 µg/m³ (60 ppb), which may be exceeded on a maximum of 25 days per calendar year. However, the UBA recommends that this value should not be exceeded at all. From a value of 180 µg/m³, the population must be informed, and from 240 µg/m³, an ozone alarm must be triggered.

There is currently no occupational exposure limit value (OEL, formerly MAK). Since no OEL has yet been established for ozone, the previous TLV of 200 µg/m³ is considered a non-binding guideline. For offices, the limit values of the Federal Environment Agency apply.

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Measure Sulphur Dioxide Limit Values Air Pollutant Icon
Sulphur dioxide (SO₂)
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Limit values
Designationning Sulphur dioxide limit values
1h-Limit value 350 µg/m³
Daylimit value 125 µg/m³
Annual/WinterLimit value 20 µg/m³


The EU has set the following sulphur dioxide limits: The one-hour limit value is 350 µg/m³, the daily limit value is 125 µg/m³. Furthermore, an alarm threshold of 500 µg/m³ applies to sulphur dioxide. A concentration of 2.5 mg/m³ (1,000 µg/m³ or 1 ppm) is set as the occupational exposure limit value (OEL) for sulphur dioxide.

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Radon Concentration Radiation Protection Icon
Radon (Rn)
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Limit values
Designationning Radon limits
EU-wide Euratom standard 300 Bq/m³ per yearthroughcut
Planningguideline value for new buildings 200 Bq/m³ per yearthroughcut
WHO recommendation 100 Bq/m³


The German Radiation Protection Act sets the reference value for radon concentrations. The limit value of 300 becquerels per cubic metre (Bq/m³) applies indoors - this means 300 decays per second per cubic metre of air. Upon request, the landlord or employer must be able to prove these values. The German Radiation Protection Commission (SSK) recommends ventilating from 250 Bq/m³ and permanently reducing the value below 100 Bq/m³ - as does the World Health Organisation WHO. At more than 1,000 Bq/m³, remediation should take place to protect against radon.

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Absolute Humidity Icon
Absolute humidity (φ)
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Limit values
Designationning Absolute humidity limits
General recommendation Minimum value 6.9 g/m³
General recommendation Maximum value 10.4 g/m³


There are no fixed limit values for absolute humidity. Recommended values are between 6.9 and 10.4 g/m³, which are the limits of too dry and too humid air at room temperature. At lower or higher temperatures, however, these values can quickly become uncomfortable.

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Measure relative humidity icon
Relative humidity (ρ)
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Limit values
Designationning Relative humidity limits
General recommendation Minimum value 40 %
General recommendation Maximum value 60 %


There are no legally specified limit values for relative humidity. Values between 40 and 60% are recommended. This is the limit for room temperature between air that is too dry (dry throat and eyes) and air that is too humid (mould!).

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Methane Greenhouse Gas Air Quality Measure Icon
Methane (CH₄)
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Limit values
Designationning Limit values methane
Lower explosionlimit (LEL) 29 g/m³ (corresponds to 4.4 vol.-%)


Since methane is non-toxic to humans, no limit values have been set for this gas. However, the high flammability of methane poses a significant risk. The lower explosion limit (LEL) is considered to be a methane content of 29 g/m³ - which corresponds to 4.4 vol.-% (volume percent). Above this level, flame propagation in the gas mixture occurs completely independently in the event of ignition (explosion).

Methane is also known as a dangerous climate gas and thus a contributor to man-made climate change. In recent years, the methane content in the atmosphere has been rising rapidly.

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Formaldehyde Pollutant Air component air-Q
Formaldehyde (CH₂O)
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Limit values
Designationning Limit values formaldehyde
Federal Institute for Risk Assessment (BfR) 0.1 ppm (corresponds to 124 µg/m³)
WHO recommendation 0.08 ppm (corresponds to approx. 100 µg/m³)
MAK value (maximum workplace concentration) 0.3 ppm (corresponds to 370 µg/m³)


The Federal Institute for Risk Assessment (BfR) sets a maximum formaldehyde concentration of 0.1 ppm (parts per million). The World Health Organisation (WHO) recommends a maximum of 0.08 ppm as the formaldehyde limit value. In the workplace, the MAK value of 0.3 ppm applies.

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✓ Measurable with the air-Q formaldehyde special, air-Q science or the formaldehyde single sensor. Formaldehyde is also detected via the VOC sensor in every air-Q, but cannot be specifically measured in the air-Q light, air-Q basic and air-Q pro.

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Air pressure (p)
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Limit values
Designationning Air pressure limits
No limit values defined -


There are no relevant limit values for air pressure in normal environments. High deviations from the normal pressure of 1 hPa can also occur at workplaces. Exemptions are required below 0.73 and above 3.6 hPa. Even at deviations of 0.1 hPa from normal air pressure, significant health restrictions are to be expected and certain groups of workers may no longer be employed.

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Noise Measure Sound Level Meter Icon
Noise (Lp)
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Limit values
Designationning Bordervalues noise
Federal ImmissionprotectionTA Noise Act - Indoor Daytime 35 dB
Nighttime 25 dB
Federal ImmissionprotectionTA Lärm - Spa Areas During the day 45 dB
At night 35 dB
Federal ImmissionprotectionTA Lärm - Pure residential areas During the day 50 dB
At night 35 dB
Federal ImmissionprotectionTA Lärm - Mixed areas Daytime 60 dB
Nighttime 45 dB
WHO recommendation Wind turbines near residential areas During the day 45 dB


In the official TA Lärm (Technical Instructions on Noise Protection), maximum limits are set for indoor areas (25 dB at night, 35 dB during the day). Outdoors, different limits apply to different areas - in pure residential areas, for example, 50 dB during the day and 35 dB at night. The WHO has made a number of recommendations for specific noise sources and areas. In the immediate vicinity of wind turbines, the WHO recommends a maximum noise level of 45 dB, traffic noise should be below 53 dB during the day and 45 dB at night - always measured outside. The Noise Vibration Occupational Health and Safety Ordinance (LärmVibrationsArbSchV) applies to protection against the effects of noise at the workplace. It specifies various limit values depending on the type of activity, duration and specific location of noise exposure. For example, there are no special limit values for offices.

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Noise Maximum Value Measure Sound Level Meter Icon
Noise maximum value (Lp_max)
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Limit values
Designationning Bordervalues noise
Federal ImmissionprotectionTA Noise Act - Indoor Daytime 35 dB
Nighttime 25 dB
Federal ImmissionprotectionTA Lärm - Spa Areas During the day 45 dB
At night 35 dB
Federal ImmissionprotectionTA Lärm - Pure residential areas During the day 50 dB
At night 35 dB
Federal ImmissionprotectionTA Lärm - Mixed areas Daytime 60 dB
Nighttime 45 dB
WHO recommendation Wind turbines near residential areas During the day 45 dB


In the official TA Lärm (Technical Instructions on Noise Protection), maximum limits are set for indoor areas (25 dB at night, 35 dB during the day). Outdoors, different limits apply to different areas - in pure residential areas, for example, 50 dB during the day and 35 dB at night. The WHO has made a number of recommendations for specific noise sources and areas. In the immediate vicinity of wind turbines, the WHO recommends a maximum noise level of 45 dB, traffic noise should be below 53 dB during the day and 45 dB at night - always measured outside. The Noise Vibration Occupational Health and Safety Ordinance (LärmVibrationsArbSchV) applies to protection against the effects of noise at the workplace. It specifies various limit values depending on the type of activity, duration and specific location of noise exposure. For example, there are no special limit values for offices.

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Measure room temperature icon
Air temperature (T)
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Limit values
Designationning Bordervalues roomtemperature
Environmentbundesamt Recommendationslung - living space 21 °C to 23 °C
Environmentbundesamt Recommendationslung - offices 21 °C to 22 °C
Environmentbundesamt Recommendationslung - childrenroom 21 °C to 23 °C
Environmentbundesamt Recommendationslung - bedroom 16 °C to 18 °C
Highestvalue according to worksitesDirective (ASR) - Offices 26 °C


The Federal Environment Agency makes recommendations for room air temperatures depending on use (e.g. living rooms 21 to 23 °C, children's rooms and bathrooms 23 °C, bedrooms 16 to 18 °C). For offices, a room temperature between 21 and 22 °C is recommended. According to the Workplace Directive (ASR), the maximum temperature in workrooms must not exceed 26 °C, otherwise the employer is obliged to take measures.

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VOC - Measure Volatile Organic Compounds Icon
Volatile Organic Compounds (VOC)
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Limit values
Designationning Limit values VOC
Federal Environment Agency - hygienically safe <1 mg/m³ – von 150 bis 400 ppb (parts per billion)
Federal Environment Agency - hygienically conspicuous 1 to 3 mg/m³ - 400 to 1200 ppb
Federal Environment Agency - hygienically questionable 3 to 10 mg/m³ - 1200 to 4000 ppb
Federal Environment Agency - hygienically unacceptable >10 mg/m³ - over 4000 ppb


The Federal Environment Agency gives recommendations for the occurrence of Volatile Organic Compounds (VOCs) ranging from hygienically harmless (below 1 mg/m³ - below 150 ppb) to hygienically conspicuous (between 1 and 3 mg/m³ - 150 to 1300 ppb) and hygienically questionable (between 3 and 10 mg/m³ - 1300 to 4000 ppb) to hygienically unacceptable (above 10 mg/m³ - above 1500 to 4000 ppb). Many legally relevant sources mention mg/m³ as the unit. However, what is measured is a mixture of many substances with different molecular masses (also referred to as TVOC), whose volume fraction in the air is expressed in ppb (parts per billion) or ppm (parts per million). In Germany, legal limits for VOCs have so far only been set for workplaces with particularly high levels of production-related pollution.

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Dew point
Dew point (Td)
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Limit values
Designationning Limit values dew point
General recommendation Minimum value 9 °C
General recommendation Maximum value 15 °C
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Nitrous oxide (N₂O) icon
Nitrous oxide (laughing gas) (N₂O)
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Limit values
Designationning Limit values nitrous oxide (N₂O)
Worksplatzlimit value (AGW) (MAK of the DFG) 100 ppm (180 mg/m³)
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Hydrogen sulphide (H₂S)
Hydrogen sulfide (H₂S)
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Limit values
Designationning Sulphur limit valueshydrogen
Workplacelimit value (AGW) 5 ppm (corresponds to approx. 7 mg/m³)
MAK value (maximum workplaceconcentration) 10 ppm (corresponds to approx. 14 mg/m³)
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Ammonia - Ammonium
Ammonia (NH₃)
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Limit values
Designationning Limit values ammonia
Recommendation Environmentbundesamt for outdoor air <700 µg/m³ (1 ppm)
Limit value according to animal protectionLivestockOrdinance (TierSchNutztV) 14,000 µg/m³ (20 ppm)
Workplacelimit value (AGW) 14,000 µg/m³ (20 ppm)
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Measure hydrogen
Hydrogen (H₂)
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Limit values

As the gas has no direct effect on human health, no limit values have been set.

Designationning Limit values hydrogen
Lower inflammationborder 4%
Upper inflammationborder 76%
Lower explosionborder 18%
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Chlorine Gas (Cl₂) Measure Icon
Chlorine / chlorine gas (Cl₂)
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Limit values
Designationning Chlorine (Cl₂) limits
Odorthreshold 0.02 ppm - 1 ppm
Workplacelimit value (AGW) 0.5 ppm (= 1.5 mg/m³ air)
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