Humans are capable of holding their breath for 30 seconds. So no respiratory problems will be faced by the people other than the patients in the hospital who need oxygen supply. For other people this event would even end before one realises. But this won't be the same case with other things around the world. 

Oxygen acts as the binding agent for concrete to stand still and strong.Make sure to stay away from the concrete structures because they will turn into dust without oxygen. Without oxygen no concrete can stand still and will collapse. So we can expect failed dams and floods at the same time collapsed buildings.

Any kind of metal which is not maintained well has a chance of being fused. This happens due to the result of no oxidation layer within metals. The oxidation layer prevents metals from getting fused. So be ready to say bye to the unused cycles and other metals that you have in your store room and garage.

If you have an idea of going to the beaches, better now you should drop it down. Because people who are already there would have experienced severe skin burns. This would have happened due to the no protection layer to the earth, which means “no ozone layer”. Sun produces the UV Rays(Ultra Violet Rays) along with the light and heat, and the ozone layer is the only protection layer that protects the earth from UV Rays. And no oxygen means no ozone layer so we can expect a lot of skin burnt people running towards the shelter to protect themselves from the rays. And now it is better for everyone to have a shelter to protect themselves.

No oxygen means, the drop down of 21% of the air pressure. This is a sudden and extreme drop down of pressure for which our ears are not capable of adapting to it. Our inner ear will burst due to this massive and inconvenient air pressure, which results in loss of hearing for sometime.

You can’t see any of the machines running due to combustion. Any kind of machine which depends on combustion will stop. This happens due to the no oxygen presence for the combustion process. So you can’t even find any candles lit and match sticks creating flames. You can also expect suddenly failed vehicles in the roads causing traffic jams other than electric vehicles. Also you can notice planes crashing and falling down if one flies above in the sky near your area. 

If you are experiencing mornings now, please be ready to face the almost black sky at the day-time itself, for 5 seconds. You don’t have to be surprised to see that black sky because there is no oxygen. Before the light rays of the sun reaches the surface of the earth, the light bounces off many particles on its way present in the air. As for the 5 seconds there is no oxygen, there would be less particles to bounce off, so we can see a dark sky, in fact almost black. 

The most dangerous part is the earth’s crust crumbling. The crust of the earth would crumble completely. This happens due to no presence of 45% of the oxygen of the earth’s crust. Without oxygen on the surface there would not be much thing left to withstand still. So the earth’s crust crumbles and continues to crumble until there’s nothing left to crumble down. And finally we all on the planet can also expect a free fall.