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Recognize that a whiff of most toxins, even in high concentration, will probably not kill you. You need a sufficient concentration in your blood - which means you have to actually get a certain number of HCN molecules to penetrate across the mucosa of the lung and into the blood stream. Typical breathing volume is about 500 mL (tidal volume), about 1/40th of a mole, so a single normal breath of 100 ppm HCN would contain 2.5 µmol of HCN.

According to the CDC, humans can tolerate inhalation of 50 ppm HCN for half an hour "without immediate or delayed effects", while 100 ppm for more than half an hour may be fatal.

The Mayo clinic reports that blood cyanide levels over 2 µg / ml are toxic; if you have 5 liters of blood, that corresponds to 10 mg. The molar mass of HCN is 27, meaning that 10 mg is 370 µmol. At 2.5 µmol / breath, you should be able to take 148 breaths; at 6 breaths per minute, that would be about 25 minutes.

All these numbers are quite consistent, and it tells you that you can tolerate a whiff of cyanide without ill effects. But it's a good idea, once you smell it, to open the windows, turn on the extractor fans, and get yourself to some fresh air.

Recognize that a whiff of most toxins, even in high concentration, will probably not kill you. You need a sufficient concentration in your blood - which means you have to actually get a certain number of HCN molecules to penetrate across the mucosa of the lung and into the blood stream. Typical breathing volume is about 500 mL (tidal volume), about 1/40th of a mole, so a single normal breath of 100 ppm HCN would contain 2.5 µmol of HCN.

According to the CDC, humans can tolerate inhalation of 50 ppm HCN for half an hour "without immediate or delayed effects", while 100 ppm for more than half an hour may be fatal.

The Mayo clinic reports that cyanide levels over 2 µg / ml are toxic; if you have 5 liters of blood, that corresponds to 10 mg. The molar mass of HCN is 27, meaning that 10 mg is 370 µmol. At 2.5 µmol / breath, you should be able to take 148 breaths; at 6 breaths per minute, that would be about 25 minutes.

All these numbers are quite consistent, and it tells you that you can tolerate a whiff of cyanide without ill effects. But it's a good idea, once you smell it, to open the windows, turn on the extractor fans, and get yourself to some fresh air.

Recognize that a whiff of most toxins, even in high concentration, will probably not kill you. You need a sufficient concentration in your blood - which means you have to actually get a certain number of HCN molecules to penetrate across the mucosa of the lung and into the blood stream. Typical breathing volume is about 500 mL (tidal volume), about 1/40th of a mole, so a single normal breath of 100 ppm HCN would contain 2.5 µmol of HCN.

According to the CDC, humans can tolerate inhalation of 50 ppm HCN for half an hour "without immediate or delayed effects", while 100 ppm for more than half an hour may be fatal.

The Mayo clinic reports that blood cyanide levels over 2 µg / ml are toxic; if you have 5 liters of blood, that corresponds to 10 mg. The molar mass of HCN is 27, meaning that 10 mg is 370 µmol. At 2.5 µmol / breath, you should be able to take 148 breaths; at 6 breaths per minute, that would be about 25 minutes.

All these numbers are quite consistent, and it tells you that you can tolerate a whiff of cyanide without ill effects. But it's a good idea, once you smell it, to open the windows, turn on the extractor fans, and get yourself to some fresh air.

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Recognize that a whiff of most toxins, even in high concentration, will probably not kill you. You need a sufficient concentration in your blood - which means you have to actually get a certain number of HCN molecules to penetrate across the mucosa of the lung and into the blood stream. Typical breathing volume is about 500 mL (tidal volume), about 1/40th of a mole, so a single normal breath of 100 ppm HCN would contain 2.5 µmol of HCN.

According to the CDC, humans can tolerate inhalation of 50 ppm HCN for half an hour "without immediate or delayed effects", while 100 ppm for more than half an hour may be fatal.

The Mayo clinic reports that cyanide levels over 2 µg / ml are toxic; if you have 5 liters of blood, that corresponds to 10 mg. The molar mass of HCN is 27, meaning that 10 mg is 370 µmol. At 2.5 µmol / breath, you should be able to take 148 breaths; at 6 breaths per minute, that would be about 25 minutes.

All these numbers are quite consistent, and it tells you that you can tolerate a whiff of cyanide without ill effects. But it's a good idea, once you smell it, to open the windows, turn on the extractor fans, and get yourself to some fresh air.