Altitudes

In high altitudes, people find it hard to breathe.

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Contrails are long, narrow, ice-crystal clouds that form behind jet planes flying at high altitudes in below-freezing temperatures. They result from the condensation of water vapor remaining in jet exhaust.

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Unlike its presence at high altitude where ozone acts as Earth's sunscreen from harmful ultraviolet radiation, at low altitudes, ozone is a health hazard contributing to respiratory problems like asthma and bronchitis.

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Boil water at least one minute before drinking it. At high altitudes, you should boil it longer.

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