Tech

DAS: all you need to know about the waves emitted by our smartphones

When designing their smartphones, manufacturers must respect a wave emission threshold in order to limit the risks to our health. This limit is indicated by the SAR. But what is it ? How do we measure it? How to limit the emissions of the waves? We explain everything to you in this complete file.

Credits: Unsplash/Robin Worrall

Who has never had a debate on the impact of smartphone waves on our health? Perhaps you have heard of DAS without really knowing what it is exactly? While the arrival of 5G is giving rise to preposterous and even conspiracy theories, a clarification is in order.

DAS, what is it? Are the waves really dangerous for our health? If so, from when? How to limit their emission? We answer all these questions in this complete file.

DAS, what is it?

DAS (or SAR in Anglo-Saxon countries) means Specific Absorption Rate. This is “an index indicating the power of a flow of energy conveyed by radiofrequency waves absorbed by the user of a radioelectric device – mobile phone, tablets, connected watch for example” (Wikipedia). He is measured in Watts per kilogram (W/kg) and must be indicated by the manufacturers.

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Formerly mandatory for smartphones only, this mention must (from July 1, 2020) appear on all products intended to be used near the human body such as tablets, watches or connected bracelets.

Three types of DAS

There are three types of SAR intended to measure the emission of waves on different parts of the human body. Also, the limit differs according to the country exposure areas. In Europe, the values ​​to be respected in order to market a product are as follows:

  • the DAS member corresponds to a connected device that is held in the hand, worn on the wrist or stored in the pocket. The emission limit is set at 4 W/kg per 10 grams of human tissue.
  • the SAR trunk responds to the case where the smartphone is stored in the pocket of a coat or in a handbag.
  • the SAR head corresponds to a telephone conversation with the smartphone glued to the ear. The limit is set at 2 W/kg per 10 grams of human tissue.

In France, the legislation obliges manufacturers to provide an accessory allowing conversation without carrying the telephone to the ear. Logically, they provide inexpensive wired headphones.

In France, it is the ANFR (National Frequency Agency) which checks the conformity of the devices marketed. Please note that these are checks and not preliminary studies. The agency therefore picks a few models from those on the market and analyzes them. Many smartphones therefore slip through the cracks. Should we be worried about it? No. Because manufacturers have every interest in displaying a correct SAR at the risk of seeing their product withdrawn from the market in the event that it exceeds the imposed limits.

To establish these emission limits, experiments were first conducted on rats. From 4 W/kg (on the whole body of the guinea pigs), the scientists observed a heating of their tissues. They then imagined a laboratory test protocol on a mannequin covered with a fiberglass shell filled with a liquid simulating human tissue. Using this tool, scientists can calculate emissions at the head, right hand, left hand and when worn on the body. This test protocol is adjusted for each frequency band of each type of network (2G, 3G, 4G and 5G).

das test
Credits: Environmental Health Trust

Thanks to these tests and the results obtained on rats, the International Commission on Non-Ionizing Radiation Protection (ICNIRP) has limited the SAR to 2 W/kg. The ANFR seeks to obtain the maximum SAR of each device studied. Also, its test protocol simulates extreme conditions: isolated laboratory, network difficult to capture, device glued for 6 minutes in several positions, constant wave emission.

In reality, the maximum SAR displayed on the boxes of your smartphones therefore corresponds to the results obtained in these extreme conditions. The actual SAR is therefore much lower especially since a smartphone only emits waves 50% of the time during a voice call and 10% when you use the internet.

If the SAR values ​​vary from one smartphone to another, it is above all because of the choice and arrangement of the components. A low SAR does not mean that your smartphone emits fewer waves than a model with a higher SAR. If its antennas are of better quality, the smartphone with the higher SAR may very well emit fewer waves than its competitor.

To know the SAR of your smartphone, tablet or connected object, several methods exist. Legislation obliges manufacturers to communicate this information on advertising content, in physical stores or on packaging. You can also find this information on the official brand website or on the small notice inside the storage box.

openbars handles
ANSES offers the Openbarres application to find out the SAR of your smartphone

ANFR also offers the application Openbars, available on Android. For years, Apple prevented the deployment of the app on the App Store. Indeed, the apple brand refused to authorize the ANFR to collect certain data, which are essential to the operation of Open Barres.

After years of negotiation, the ANFR announced in December 2022 the arrival of the Open Barres app on the App Store. It was time. Now that that is said, here are the different features offered by this totally free tool:

  • Visualize the location of telecom sites close to your position, with the operators and systems installed there
  • Have weekly updated data on the deployment of 5G networks open to the public in mainland France, without the need to use a 5G phone
  • Get to know the “good behavior to reduce exposure to radiofrequency waves emitted by mobile phones” published by the Ministry responsible for Health, the Ministry responsible for the Environment, ANSES and ANFR, and adapt the use of your mobile phone to these recommendations

Of the harmfulness of the waves

For a long time, the question of exposure to waves was debated. Are they really harmful to our health? If the scientists themselves recognized that they lacked perspective to decide, some studies suggested that prolonged exposure to waves could have an impact.

Since the end of 2019, it is officially recognized that excessively intense and/or prolonged exposure to waves can have harmful effects on our health. The National Agency for Food, Environmental and Occupational Health and Safety (ANSES) recognized on October 21, 2019 that a SAR level above 2 W/kg could have biological effects on brain activity.

The World Health Organization has classified exposure to electromagnetic waves as carcinogenic. Be careful, this does not mean that the waves of smartphones have increased the number of cancers. On the contrary, most research indicates that a causal link between smartphone use and head cancer does not exist. For twenty years now at least half of the population has been using mobile phones. If this increased the risk of cancer, we would have seen a 30% increase in cases of gliomas, which is not the case, can we read on the latest WHO report.

What are anti-radiation products worth?

Faced with fears surrounding electromagnetic waves, many manufacturers have rushed into the niche of anti-wave accessories. Some are not lacking in audacity. On the internet, you can find anti-radiation patches, promising to reduce by at least 60% our exposure to the waves compared to the maximum SAR. By the way, these patches would improve the network quality of our smartphones. The main problem is that we do not know the quantity of waves emitted in real time. The indicated SAR is a maximum value, so we saw above that a smartphone can very well emit much less waves than that displayed on the official documentation. It is therefore impossible to draw any conclusions.

Anti-radiation hulls can have the opposite effect. Indeed, they are designed to reduce the signal and therefore the capture of the network. By degrading the network performance of the smartphone, the shells force it to use the antennas more and therefore to emit more waves to capture the signal. And we are not even talking about the impact on the battery which may melt like snow in the sun.

anti-wave underpants
Credits: Spartan

Finally, while some studies suggested that smartphones could make men less fertile, some brands have embarked on the great adventure of anti-radiation underwear. Others have extended their ranges to t-shirts, caps or hats, with (of course) sometimes indecent prices. Alerted by the phenomenon, ANSES looked into the subject in 2018. The conclusion of the study is without appeal :

The use of a clothing accessory (cap, headband, etc.) slightly and very locally reduces a person’s exposure to electromagnetic fields. Due to the many openings, this type of product is not sufficient to effectively reduce the overall exposure of the person and may increase the value of the exposure at the periphery of the device.

In summary, the SAR remains the only reliable indicator concerning the emission of waves by our electronic devices. And if you have read this file correctly, it should no longer hold any secrets for you.

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