"Do not scrub or scratch the skin", Guam authorities advise, adding that the hair should be washed with shampoo or soap, while conditioner should not be used as it would bind radioactive material to the hair.
Japan was on Saturday deploying its Patriot missile defence system after North Korea threatened to fire ballistic missiles over the country towards the US Pacific territory of Guam, reports said.
"We are with you a thousand percent", Mr Trump said, according to video of the call posted on Mr Calvo's Facebook page.
Amid escalating tensions, Trump tweeted Friday: "Military solutions are now fully in place, locked and loaded, should North Korea act unwisely".
Washington wants to stop Pyongyang from developing nuclear missiles that could hit the United States.
While experts estimate the consequences and economic impact of an imminent us vs North Korea war, some Guamanians are stockpiling essentials to survive while taking shelter if Pyongyang makes good on its promise to strike the island.
North Korea Tensions Hit Global Stock Markets
In currency markets, the Canadian dollar was trading at an average price of 78.71 cents United States , down 0.20 of a USA cent. As a result, the yield on the benchmark ten-year note, which moves opposite of its price, dipped by 2.3 basis points to 2.189%.
Guam, an island half the size of Hong Kong and some 7,000 km from the United States mainland, is a target because of its naval base and air force base, from which two B-1B supersonic bombers were deployed close to the Korean peninsula on Tuesday.
The fact sheet, first reported Friday by the Pacific Daily News, explains that brick or concrete structures are the safest places to shelter from nuclear fallout, and that those with thick walls and roofs best absorb radioactive particles.
It said if an attack warning came, residents should seek shelter and stay there for at least 24 hours.
Those who can't get indoors or behind some type of protections should simply lie down and cover their heads.
After a missile attack is over, Guam residents are advised to keep listening for official information from authorities to know what to do next.