N1VUX is my FCC-issued ham radio callsign.
«... so much [so] that they are at risk of deep vein thrombosis[.] The proportion of oxygen in the air breathed in on board an aircraft in flight falls from 21 per cent to as little as 15 per cent. As well as contributing to a dangerous thickening of the blood that can cause DVT, a drop in blood oxygen can impair mental performance, give passengers headaches and make them tired. People with heart disease are more likely to suffer angina and those with unhealthy lungs have a greater risk of becoming ill.»
«"The blood becomes thicker due to ankle swelling and people are often dehydrated because they don't drink enough and because of the dry air.