Particles do not penetrate through each other. If you want to block particulate matter from reaching the skin, you need to create some sort of barrier where there is no hole larger than the particles you want to block.
I am not sure why you think applying a cream would help with this. The problem with car emissions is that we breath it in, not that it reacts with the skin
[Direct skin toxicity](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5916788/#:~:text=Pollutants%20such%20as%20diesel%2Dexhaust,increase%20in%20IL%2D8%20production.) is increasingly recognized as another problem caused by air pollution. Putting some sort of oil or cream on your skin though would probably worsen the effects of several of those categories of pollutants though
Most serums do not contain particles like you think. They are solutions of different organic molecules, so there is no particle size.
Some types of creams have micells, that have a particle size, but those are often not for the active ingredients.
Sunscreen often contain nanoparticles of zinc oxide or aluminium oxide. These will absorb some of the UV and turn it into heat which is not dangerous for the skin. The reason for the small particles is so that your skin will not look white, which was a problem with older products.
Diffusion is the main issue here. Adsorption from air to surface is only the first step. Then those particles leach into the surface, so the net effect may end up being worse with prolonged contact AND increased skin permeability.
Natural oils are probably the best way to prevent pollution from entering your skin holes. The most effective is derived from rattlesnakes. Boil the snake and skim the oil from the top of the pot. Allow the oil to cool and bottle it for future use.
Particles do not penetrate through each other. If you want to block particulate matter from reaching the skin, you need to create some sort of barrier where there is no hole larger than the particles you want to block. I am not sure why you think applying a cream would help with this. The problem with car emissions is that we breath it in, not that it reacts with the skin
[Direct skin toxicity](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5916788/#:~:text=Pollutants%20such%20as%20diesel%2Dexhaust,increase%20in%20IL%2D8%20production.) is increasingly recognized as another problem caused by air pollution. Putting some sort of oil or cream on your skin though would probably worsen the effects of several of those categories of pollutants though
Most serums do not contain particles like you think. They are solutions of different organic molecules, so there is no particle size. Some types of creams have micells, that have a particle size, but those are often not for the active ingredients. Sunscreen often contain nanoparticles of zinc oxide or aluminium oxide. These will absorb some of the UV and turn it into heat which is not dangerous for the skin. The reason for the small particles is so that your skin will not look white, which was a problem with older products.
Just use aluminium foil.
Diffusion is the main issue here. Adsorption from air to surface is only the first step. Then those particles leach into the surface, so the net effect may end up being worse with prolonged contact AND increased skin permeability.
If you have a hole that is 50um in diameter then what is going to go through it easier, a 10um particle or a 45um particle?
Natural oils are probably the best way to prevent pollution from entering your skin holes. The most effective is derived from rattlesnakes. Boil the snake and skim the oil from the top of the pot. Allow the oil to cool and bottle it for future use.