"Cough, cough, cough!" Chen Xin was jolted awake by the suffocating smoke.
It was the third day since Chen Xin had entered the shelter, and after two days of adaptation and adjustment, he felt that he had grown accustomed to life in the shelter.
But today, for some unknown reason, the entire shelter was filled with a choking smokiness, which woke Chen Xin from his sleep.
While coughing and covering his mouth and nose, Chen Xin got up from the bed and turned on the room's light.
He trembled as he dressed, yet he still felt a bit dizzy, even his breathing was labored.
Chen Xin knew it wasn't because he was still groggy from sleep, but rather the air was filled with harmful gases mixed in the choking smoke, which affected his breathing as he had inhaled quite a bit of smoke in his sleep.
If he hadn't been woken up by the smoke, continuing to sleep would likely lead to death from oxygen deprivation or poisoning by the toxic gases.
Realizing the situation, Chen Xin quickly found a gas mask and an oxygen tank from the cabinet, taking several gulps of oxygen before putting on the gas mask.
The oxygen helped Chen Xin recover, giving him the clarity to think about what could have happened.
The shelter shouldn't be on fire, as he hadn't used any open flames; he had even been using an induction cooker to boil water these past two days.
But at this moment, Chen Xin didn't dwell on it, running to the garage to grab the small fire extinguisher from the car's trunk before checking the shelter's various areas.
To his surprise, the shelter wasn't on fire, nor was there any place visibly smoking.
Where did this choking smoke come from? This acrid smell must be from something burning, Chen Xin couldn't believe otherwise.
Upon rechecking, Chen Xin finally discovered that the smoke was coming from the ventilation system, entering the shelter from outside.
This realization hit Chen Xin — it was a fire outside!
Had the wildfire, sparked by the meteor impact, reached here after two days?
This realization made Chen Xin feel particularly helpless, knowing the cause didn't solve the problem.
It was a global conflagration, most vegetation would burn, and though Chen Xin hadn't ventured outside, he was confident the mountain where his shelter was located had caught fire; otherwise, his shelter wouldn't have such a dense smoke smell.
It's worth noting that the shelter's ventilation system was specially designed so smoke and toxic gases would be filtered under normal circumstances.
But the current situation... clearly, the external smoke concentration had surpassed the filtration and bearing limits of the ventilation system.
Chen Xin felt helpless and desperate; was he to die from smoke inhalation?
Though he had prepared a gas mask and oxygen tank, their usage time was limited.
In this environment of increasing smoke density, even with a high-quality gas mask, Chen Xin could only last a few hours before needing to replace the filter to maintain effectiveness, and the oxygen tank could last only two hours.
Although Chen Xin estimated the wildfire outside wouldn't burn for long due to the temperature drop caused by the dust clouds obscuring the sky, it would still last for several days, even over a week.
Originally, Chen Xin believed the shelter's ventilation system could guarantee his survival during this period, yet reality had dealt him a harsh blow.
The ventilation system he thought could withstand the wildfire evidently couldn't. If Chen Xin couldn't devise a solution, he'd likely die from smoke inhalation in the shelter, akin to those who perished in fire.
Escape? That was clearly impossible.
The smoke had reached the shelter, indicating the area was surrounded by wildfire; even if Chen Xin opened the shelter door and ran out, he'd merely go from smoked meat to roast duck.
And even if he could escape, where would he go?
This wildfire wasn't confined to one mountain; it was a global inferno.
At this moment, over 90% of Blue Planet's vegetation had caught fire from the heat released by the meteor impact, and flames raged everywhere on the surface, leaving no place to escape.
The sea might be fire-free, but how could Chen Xin travel from inland to the coast?
All transportation systems had ceased operation following the meteor impact; the state might have secret routes, but such things wouldn't be accessible to an ordinary person like Chen Xin.
And if he could use such secret routes, Chen Xin wouldn't need to run anywhere, just stay in the state's secret shelter.
The official shelter was indeed an option.
But there was a critical issue — how would Chen Xin get the official shelter, already sealed, to open its doors for him amidst a global inferno?
Even the door to Chen Xin's own shelter was a 12 cm thick solid metal blast door. Never mind knocking — even hammering from outside might not be heard inside, especially since Chen Xin had installed two doors for safety.
Thus, one can imagine the state of the official shelter's door.
So, from the start, Chen Xin hadn't considered escape.
But if not escape, what could he do to survive?
The ventilation system had reached its limit; unless he replaced it with a stronger system, the outcome would be death by smoke inhalation in his meticulously crafted shelter!
Wait! Suddenly, Chen Xin snapped to attention, realizing a key factor he had overlooked.
He could indeed upgrade to a stronger ventilation system because he had the system!
Recalling the system, Chen Xin hastily summoned its interface and focused on the shelter's ventilation ducts.
Sure enough, the ventilation ducts lit up within his sight, providing an upgrade plan.
"Natural Ventilation Air System"
"Upgrade Plan One: Upgrade filter media, enhance air filtration level, add forced mechanical ventilation function, upgrade cost: 100 survival points"
"Upgrade Plan Two: Upgrade duct material, enhance insulation level, add temperature regulation function, upgrade cost: 100 survival points"
Without a second thought, Chen Xin chose the first upgrade plan.
Upon confirmation, a grid-like light, reminiscent of the system's initial activation, enveloped the ventilation ducts.
Quickly, the light faded, and the ventilation system in Chen Xin's shelter was completely renewed, upgrade complete.