The most important use of the ideal gas law in daily life is in estimating the amount of ventilation a building needs for human use; another use is in estimating cabin pressurization in airplanes. In any closed environment with many people inside, the amount of air that gets through the walls may be insufficient. The amount of oxygen in a given volume is determined by this law.
The ideal gas laws give the relationships between pressure, temperature and volume for any mix of ideal gases. Unfortunately, only the noble gases such as helium and neon are actually close to ideal, but the ideal gas law is still a close enough approximation for many purposes.
In any environment where the intake of oxygen and the release of carbon dioxide is likely to be insufficient for the number of people inside, some type of ventilation must be installed. This ventilation must be lesser or greater depending on the number of people and their level of activity. In sealed environments such as an airplane at cruising altitude, air must be pumped in at a greater pressure than the outside pressure. The ideal gas laws, combined with information about the average pressure and percent of oxygen in the air, tell how much oxygen needs to be brought in to keep the air fresh and sufficiently oxygenated.