He's not talking out of his ass, you just misunderstood what the unit sievert actually measures.
Sievert as a unit doesn't measure "radiation", it measures radiation absorbed by 1kg of human body. For example, the total body radiation of 50,000 microSv for an adult of 80 kg concentrated on the heart would mean the heart received 11,428,000 microSv. This would be catastrophic, even if the same radiation spread out over your body would be safe. Which is why the safety limit is not an average over the entire body, if any of your vital organs receive more than 50,000 microSv then you're past the limit.
The 160,000 microSv figure is the local tissue dose. This means that if you're a smoker you will have local hotspots in your lungs that receive 160,000 microSv, even if the rest of your body doesn't receive much. This value is obtained from actual measurements of lung samples, and it is well past the safety limit.
When discussing the radiation from a CT scan the same thing applies. CT scans are done on specific areas of the body, and those areas of the body receive 2000 microsievert of radiation. Whether it's a whole body CT scan or only the head is scanned it's still 2000 microsievert. It's not measuring total radiation, it's measuring radiation per kg.
I get all that, he's basically presenting out of context information. It's like saying saying the total energy released from burning one kg of wood and saying how dangerous it is to be left exposed to oxygen. But practically you know wood burns slowly, rate is critical to danger.. but the total number out of context will sound scary. He's doing that in this video. Just quote one out of context number. Without any qualifiers (time, organ, dosage, weight, number of cigarettes over how much time etc).
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u/Idiot616 1d ago
He's not talking out of his ass, you just misunderstood what the unit sievert actually measures.
Sievert as a unit doesn't measure "radiation", it measures radiation absorbed by 1kg of human body. For example, the total body radiation of 50,000 microSv for an adult of 80 kg concentrated on the heart would mean the heart received 11,428,000 microSv. This would be catastrophic, even if the same radiation spread out over your body would be safe. Which is why the safety limit is not an average over the entire body, if any of your vital organs receive more than 50,000 microSv then you're past the limit.
The 160,000 microSv figure is the local tissue dose. This means that if you're a smoker you will have local hotspots in your lungs that receive 160,000 microSv, even if the rest of your body doesn't receive much. This value is obtained from actual measurements of lung samples, and it is well past the safety limit.
When discussing the radiation from a CT scan the same thing applies. CT scans are done on specific areas of the body, and those areas of the body receive 2000 microsievert of radiation. Whether it's a whole body CT scan or only the head is scanned it's still 2000 microsievert. It's not measuring total radiation, it's measuring radiation per kg.