Chapter 27: 1st upgrade

　　 "Cough cough cough!" Chen Xin was awake.
　　 Today is the third day that Chen Xin entered the shelter. After two days of adaptation and adjustment, Chen Xin feels that he has adapted to life in the shelter.
　　 It’s just that I don’t know why today, the whole refuge is filled with the smell of choking smoke, which makes Chen Xin directly awake from his sleep.
　　 Coughing and covering his mouth and nose, Chen Xin got up from the bed and turned on the light in the room.
　　 He tremblingly put on his clothes, but he still felt dizzy, and even his breathing was not smooth.
　　 Chen Xin knew that this was not because he hadn't woken up yet, but because there were harmful gases in the choking smoke in the air. He inhaled a lot of smoke in his sleep, which affected his breathing.
　　 If it wasn't for him to be woken up and continue to sleep like this, it is most likely that he died due to lack of oxygen or harmful gas poisoning in his sleep.
　　 Chen Xin, who reacted, hurriedly found the gas mask and an oxygen cylinder from the cabinet on the side. After taking a few breaths of oxygen, he put on the gas mask.
　　 After taking a few breaths of oxygen, Chen Xin finally eased over. Only then did he have spare time to think about what happened.
　　 There should be no fire in the refuge, because he has not used any open flame at all, and even used an induction cooker to boil water in the past two days.
　　 But at this moment, Chen Xin didn't think too much. He ran to the garage and picked up the small fire extinguisher placed in the trunk of the car. Only then did he check the various places in the shelter.
　　 However, what made Chen Xin very strange was that the refuge did not catch fire, and there was no place to smoke.
　　 Where does the choking smoke in the air come from? Obviously, the choking gas smelled after something burned. Chen Xin absolutely didn't believe it if nothing burned.
　　 But when Chen Xin started to check again, he finally found that the smoke was coming in from the ventilator of the refuge, and the smell of smoke had entered the refuge from outside.
　　 This discovery made Chen Xin react, it was a fire outside!
　　 In two days, has the fire caused by the meteorite impact finally burned here?
　　 But this discovery made Chen Xin feel extremely helpless, because even if he knew the reason, he couldn't solve the problem.
That is a big fire that has spread to the entire world. Most of the vegetation will be ignited. Although Chen Xin has not gone out, he believes that the mountain where his refuge is located should have already been burned, otherwise he will not be let go. Take refuge in all such strong smoke.
　　 Please know that the ventilation system of the shelter is specially designed, so that smoke and toxic and harmful gases will be filtered under normal circumstances.
　　 But the current situation... Obviously, the external smoke concentration has exceeded the limit of filtration and tolerance of the ventilation system.
　　 Chen Xin feels helpless and desperate, is he about to be so smoked to death?
　　 Although he prepared gas masks and oxygen cylinders, there is a limit to how long these things can be used.
In this environment where the smoke is gradually dense, even if the quality of the gas mask bought by Chen Xin is good enough, it can only last a few hours at most. The filter element on it must be replaced to ensure the filtering effect, and the oxygen cylinder can only be used. Two hours.
　　 Although according to Chen Xin's estimation, the outside mountain fire will not last long and will be extinguished due to the drop in temperature caused by the sky being obscured by dust clouds, but this time will still last for several days or even more than a week.
　　 Originally, Chen Xin thought that his refuge ventilation system was enough to ensure his survival for such a long time, but now the reality has given him a merciless slap.
Obviously, the ventilation system that was previously thought to be able to withstand the attack of the mountain fire is obviously not resistant. If Chen Xin can't figure out a solution, after the gas mask and oxygen cylinder fail, he is likely to be smoked to death in the fire scene. Like people, was smoked to death in this refuge.
　　 escape? This is obviously impossible.
　　 The smoke came into the refuge, and it was conceivable that the outside was surrounded by wildfires. Even if Chen Xin opened the door of the refuge and ran out, it would only change from bacon to roast duck in the oven.
　　 And even if he can run out, where can he go?
　　 The fire is not his mountain top, but the super fire all over the world.
　　 At this moment, more than 90% of the vegetation on the Blue Star has been ignited by the heat released by the impact of the meteorite. Flames are burning everywhere on the Blue Star, and there is nowhere to escape.
　　 There may be no flames on the sea, but how does Chen Xin run from the inland to the coast?
　　 Now all the transportation systems have been shut down due to the impact of the meteorite. The country may have secret routes, but how can this kind of thing be opened to ordinary people like Chen Xin?
　　 And you can use this secret line, Chen Xin ran a hammer and stayed in the country's secret bunker.
　　 As for the official refuge, that is indeed an option.
　　 There is only a core issue here, and that is how should Chen Xin let the closed official shelter open the door for him under the circumstances of the fire. UU reading www.uukANAshu.com
You should know that even Chen Xin’s own refuge door is a 12 cm thick solid metal explosion-proof door, let alone knocking with your hand, you just hit it with a hammer on the outside, you may not hear it inside, let alone for safety reasons, Chen Two new doors were installed.
　　 One can imagine what the gate of the official refuge should be like.
　　 So Chen Xin hadn't considered the option of escape from the beginning.
　　 If I just don’t escape, what should I do to survive?
　　 The ventilation system has now reached its limit. Unless I change to a stronger new ventilation system, I will end up being smoked to death in this self-made refuge!
and many more! Chen Xin suddenly felt aroused and thought of an important point he had overlooked.
　　 He can indeed change to a stronger ventilation system, because he has a system!
　　 Chen Xin, who thought of the system, hurriedly called out the system interface, and then directed his sight to the ventilation duct of his refuge.
　　 As expected, the ventilation duct in the line of sight lit up, and an upgrade plan was given.
　　"Natural ventilation system"
　　"Upgrade plan 1: Upgrade filter material, improve air filtration level, increase forced mechanical ventilation function, upgrade required survival point 100"
　　 "Upgrade plan 2: Upgrade pipe material, increase insulation level, increase temperature adjustment function, upgrade required survival point 100"
　　 Chen Xin didn't even think about it, so he directly chose the first upgrade plan.
　　 With his confirmation, the grid-like light appeared again in the realization as it was when the system was started for the first time, but this time the light only covered the ventilation duct.
　　 Soon, the brilliance dissipated, and the ventilation ducts of the Chenxin Refuge had been renewed and the upgrade was completed.