A "greenhouse" gas or "greenhouse" effect really has nothing to do with a literal greenhouse.

A molecule can only absorb IR if its vibrational modes cause a change in its dipole moment. No matter how you configure the two nitrogens of N2, it will always have zero dipole. Therefore, N2 is not a greenhouse gas, but if you bend a CO2 molecule, it will have a net dipole.

This means it will absorb IR photons of certain wavelengths and become excited where the wavelengths are associated with vibrational modes of the molecules.

Once a greenhouse gas has absorbed an IR photon it could: transfer the photon's energy to another gas molecule during a collision, relax and re-emit the photon, or lose the energy by combination of collision and emisssion which will result in emission of a photon with a different wavelength than the original photon.

As greenhouse gas concentration increases, re-emitted photons are more likely to be absorbed by another molecule, providing resistance to the energy leaving the earth.

https://www.mdpi.com/1999-4915/11/3/226

https://pubmed.ncbi.nlm.nih.gov/32092482/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7939543/

They have done studies which indicate different individuals are more/less susceptible to certain viruses based on genetics. For example, some studies have indicated that blood type makes people more or less susceptible. As an example, type O might be less susceptible to Covid, but more susceptible to norovirus.

I think it would be interesting if this turned out to be true for something like blood type where individuals may express one type, but may also carry genes for other types.

Having different genes in the gene pool would allow some members of the group to survive a certain pathogen because they were less susceptible because they expressed that gene(s) while carrying the gene(s) which would allow for less susceptibility to other viruses. This would allow the survivors to repopulate with the full gene package.

The immune system attempts to clear asbestos from the lungs (but isn't able to very well) and in doing so creates a lot of damage. The process the body uses releases a lot of reactive oxygen species (which damage DNA).

Asbestos is present in the natural environment and in industrial uses and as a result we all have asbestos fibers in our lungs which cause damage, but a little damage is not enough to cause problems. It's those who have regular high exposure over many years in the occupational setting who will develop problems.

conventional thermonuclear is like fission-fusion-fission

a neutron bomb is more like fission-fusion

Instead of using the high speed fusion neutrons to induce more fission, you just let them escape.

>However, there's also a chance that a virus can be exhaled immediately after getting breathed in.

Right, If exhaled immediately after breathing it in, it never deposited in your respiratory system to begin with.

Particles in the 0.3 micron diameter range are very evasive. They can follow stream lines around obstacles and they are too big to be influenced by diffusion (random motion of air molecules) so air molecules cannot "bump" them into a surface.

A droplet nuclei carrying virions in this size range could be inhaled and exhaled right back out. This size range is what an N95 is designed to filter out 95% of the time. For particles larger or smaller than 0.3 microns, an N95 filters more than 95%.

There is a statistical distribution for all of these time periods and a lot could depend on things like the infectious dose you received, your immune system's abilities, the particular strain of the virus, how susceptible your cells are to infection with the virus (e.g. do your cells have a high concentration of the receptor the virus is looking for to gain access to your cells?), etc.

I said "Shortly after reaching peak concentration, you begin feeling symptoms", but this is not correct.

Typically peak concentration would hit shortly *after* feeling symptoms rather than before. However, you will be highly infectious a up to several hours before feeling symptoms for influenza.

The high probability zone of being being contagious before symptoms is somewhere around 36-48 hours after exposure for influenza, but someone below mentioned that it could be much shorter for influenza B.

This is just where most people will be contagious. It's possible you would be contagious 24 hours after exposure or not until 72 hours or more.

No, they are not immediately contagious. It could take days to become contagious.

Initially the virus multiplies unchecked and it reaches a peak concentration. This is when you are most contagious. Shortly after reaching peak concentration, you begin feeling symptoms as the immune system has realized it is under attack. Normally by the time you feel symptoms the concentration of the virus in your body has already begun to decrease thanks to the immune response.

This is true of influenza and many other viruses. The time it takes between you getting infected and symptom onset is called the incubation period and it's normally more than 24 hours for influenza.

For Covid-19 the average incubation period is several days, but you could be spreading the virus for 24 hours or a little longer before you first feel symptoms.

You feel fine, but you are highly contagious. Because you feel fine you are likely to be near people and talking to them in close proximity. This is where the virus shines. As you speak, microscopic spit balls filled with virions are floating through the air and those nearby are breathing them in.

Emergency rooms will normally see an spike in influenza this time of year in the US. A few days after friends and family congregated closely together for Thanksgiving.

Edit: Peak concentration is typically reached *shortly after feeling symptoms* rather than shortly before as stated above.

One reason could be that aerobic exercise causes damage due to the formation of reactive oxygen species (ROS) which damage DNA and other cellular structures.

The body compensates by upregulating repair enzymes which are then maintained at a higher concentration (even when are you not exercising). Since way more time is spent not exercising than exercising, the net effect is more protection from oxidative stress.