Hello everybody my name is Zohir Chowdhury, and I will talk about natural source of ionizing
radiation and as an example we'll talk about rhythm before we can start our discussion on radon
we must understand the radioactive half-life what is half-life radioactive half-life is the time it
takes half the radioactive atoms present to decay so for example in here we have 16 atoms from here
from 16 you have 8 so half of them are gone in the next radioactive half-life from 8 you go to 4 in
the next one from 4 to 2 and this is an another example of radioactive half-life it starts off
at 100 after one half-life it is half of 150 and then in the second half-life is half of the second
which is 25 and then for the third half-life is half of this 12.5 and so forth so as you can see
it takes multiple half lights for a radioactive product to start at let's say 100% to go down to
something close to zero with that knowledge we can start approaching this star this topic about radom
so what is radon radon is a colorless odorless gas that is produced naturally by the decay of
natural radioactive materials in the earth radon seeps into home through uranium containing soil
and in water from wells those are major sources of freedom and radon gas further decays into
short-lived daughter products they're attached to particles and can be deposited in the deep lung
so essentially radon daughter products they have very short half-lives as we'll see later when this
decayed they cause radiation exposure to nearby lung tissues it is estimated that five to twenty
thousand lung cancer death are caused by radon alone in the u.s. so that's a very large cause
of lung cancer that in the US and in the indoor air that comes from the soil is to be less than
1% however for houses with low end or pressure and poorly seal foundation they may draw as much
as 20% of the air from the soil as you can see as you can see in here radioactive isotopes from
the soil once it decays into radon radon is a gas which slowly seeps up from the soil into the air
and as it seeps up it can find cracks and pipes and progressively go into the basement or other
tight spaces in our home and accumulate there the uranium radioactive decay chain is shown in here
so from in the top you can see uranium 238 and which is undergoing alpha decay diagonally beta
decay horizontally in this reverse section alpha beta alpha beta and alpha so as it goes to alpha
decay uranium is becoming thorium then to beta decay is becoming protective and then again to
uranium 234 and this process continues until it reaches radon or RN in here this process of
radioactive decay is also shown in here with the name of all of these radioactive isotopes and the
specific type of radiation that dominates with the half-life of that process and zooming in into
radon radioactive decay so once it reaches radon within a few within a very short time it becomes
polonium and then lad and then bismuth and then polonium and then begin lad in fact from radon
to lad if you can take a look in here there's multiple radioactive decay products and in in
here it takes three minutes 27 minutes 20 minutes less than a second and then finally 20 years and
as all of this multiple radioactive decay happens alpha alpha beta and are released including some
gamma as well so the problem would reason as we can see that once radon accumulates in our inner
inner in a basement and we go to the basement within a very short period of time that radon
can cause significant exposure to our lung tissue because of the very fast half-life of its tartar
products this map in the shows different zones within the US and in California zoomed in where
radon exposure can be the highest in red moderate in orange and then low in yellow in fact most of
California seems to have moderate to low except Santa Barbara County and in the u.s. is mostly in
the Midwest where high exposure of radon in the soil can happen it is said that a 1,000 square
foot house with 4 picoCuries per liter of radon has nearly 2-million grade on atoms decaying in
at every minute so the health effects from radon it's similar to the alpha and beta health effects
that we mentioned earlier it poses significant internal damage with alpha beta opposes both
external damage as well as internal damage and because of rayon is a gas it quickly goes inside
our lung and is the number two leading cause of lung cancer after environmental tobacco smoke
in fact almost 21,000 lung cancer deaths have been reported from radon every year in the US
so quick concept check which of the following factors affect an individual's exposure to
radiation D all of the above why I loved above because as we just learn geographical location
it's because of the natural exposure occupational depending on whether in your occupation you may
have radiation exposure needs to be understood as well as medical history whether you have
had significant x-rays or other types of radio radiation therapy so all of the is the answer
another quick concept check true/false radon is a natural source of radiation true alright thank you