Strep throat Strep throat is a throat infection causing symptoms including a red sore throat with white patches. Hay fever Hay fever, an allergic reaction to outdoor pollens and molds, causes nasal congestion, itchy eyes, and more.
Air Density is the mass per unit volume of the air. For example, the standard air density at sea level is 1.225 kg/m 3 (0.076474 pounds/ft 3). Relative Density is the ratio of the actual air density to the standard sea level density, expressed as a percentage.
Less air density means less lift. The air density at sea level is 1.225 kg per cubic meter (Source). However, as you go higher above sea level, air density begins to decrease. This is why people sometimes have difficulty breathing at higher altitudes in mountainous regions.