Sizzling heat wave creates health hazard in southwestern US

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(AP Photo/Matt York) (AP Photo/Matt York)
PHOENIX (AP) -

The southwestern U.S. is about to feel the wrath of a punishing heat wave that includes a forecast of 120 degrees (48.8 Celsius) in Phoenix - a temperature not seen in the desert city in more than 20 years.

The broiling temperatures will also be felt in Las Vegas and Southern California, creating a public health hazard. Rising temps are being closely watched by everyone from airline pilots and emergency room doctors to power grid managers and mountain cities unaccustomed to heat waves.

[SPECIAL SECTION: Extreme heat]

Even cities accustomed to dealing with 110-degree (43-Celsius) days are grappling with the new problems that arise from 120 degrees (48.8 Celsius).

Here is a look at five things related to the heat wave:

HITTING 120 IS RARE

The heat wave, which is expected to peak Tuesday, is forecast to be the hottest weather in Phoenix in decades.

Wunderground Weather Historian Christopher C. Burt said Phoenix temperatures rose to 120 degrees and above only three times in recorded history - twice in 1990 and once in 1995.

Burt said the city has hit 118 degrees 11 times, most recently last summer.

It could be worse: Death Valley could see 124 degrees on Tuesday.

AIRLINES WATCHING THE HEAT

When the temperature soars, it's harder for airplanes to take off.

American Airlines pilot Shane Coffey said extreme heat creates changes in the air density that make it harder for airplanes to take off, meaning pilots have to use more thrust or impose weight restrictions such as flying with less cargo.

Air density on a 90-degree (32-Celsius) day in Denver at more than 5,000 feet elevation is similar to a 120-degree (48.9-Celsius) day in Phoenix at 1,100 feet above sea level, he said.

In 1990, amid a similar heat wave, flights were cancelled at the Phoenix airport because there was too much uncertainty about how the heat would affect aviation performance. Now, airlines have a better understanding, but the heat is still a concern - primarily for smaller, regional jets.

Airlines will be closely monitoring the heat this week and some flights could be affected.

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110 vs. 120

Residents of Phoenix and Las Vegas deal with 110-degree (43-Celsius) days fairly often in the summer - but how much more strain does 120 degrees (48.9 Celsius) put on the body?

Dr. Moneesh Bhow, medical director for Banner University Medical Center Emergency department, said the body's internal cooling mechanisms are ineffective when temps reach above 110 degrees.

One of the ways the body cools itself is by radiating heat through the skin into the air, but that system reverses when external temperatures climb to 110 or higher.

"When that happens we have to rely on our second mechanism, which is sweating," Bhow said. Sweat makes your skin feel cooler and some heat is removed as it evaporates.

He noted staying hydrated is crucial to perspiring and staying cool.

The state Department of Health Services says nearly 2,000 people visit Arizona emergency rooms every year because of heat-related illnesses.

Bhow said patients can present with a variety of illnesses - ranging from a simple heat rash to a severe heat stroke.

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HEAT DEATHS

The heat is a serious public health hazard in places such as Phoenix and Las Vegas where temperatures routinely exceed 110 degrees (43 Celsius) in the summer months.

The county that is home to Phoenix had 130 heat-related deaths in 2016, the highest number in more than a decade. It wasn't immediately clear what caused the uptick.

Kate Goodin, epidemiology and data services program manager at the Maricopa County Department of Public Health, said heat-related deaths span the entire Phoenix metro area, but underlying social and economic factors also have an impact.

Homeless people comprised one-third of heat-related deaths in 2016, according to county records. Most of the others involved people with non-functioning air conditioners.

"People who are economically disadvantaged have a harder time paying for increased electricity bills or keeping their water on throughout the entire year and those factors can predispose you to heat-related illness," Goodin said.

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TOO HOT IN THE MOUNTAINS

People typically flee for cooler mountain climates when it gets hot, but going north won't provide much of an escape this time.

Flagstaff is expected to spend most of the week with highs above 90 degrees (32 Celsius), which is so rare many residents don't have air conditioning.

"Extremely high temperatures are a little unusual for northern Arizona," said Coconino County's Deputy Chief Health Officer Mike Oxtoby.

Residents without air conditioners are advised to "pull shades over the windows and use cross-ventilation and fans to cool rooms."

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BURN WARNING

Surgeons at the major burn center serving Arizona are urging people to be aware of the danger of severe burns caused by excessive heat blanketing the southwestern United States.

Dr. Kevin Foster of the Arizona Burn Center in Phoenix issued the warning Monday.

He says second and third degree burns from hot asphalt and concrete, playground equipment, car and truck interiors and scalding water from outdoor hoses are common when temperatures exceed 100 degrees.

Temperatures in parts of Arizona, Nevada, and California are expected to top 115 degrees this week.

Foster says young children are particularly vulnerable because their skin is more sensitive.

The warning also applies to pets.

First aid for burns involves pouring cool water over the area for several minutes and seeking medical attention.

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LAS VEGAS

Tourists hitting the Las Vegas Strip will feel the sizzle Monday as temperatures could top 114 degrees.

Meteorologist Ashley Allen with The National Weather Service in Las Vegas says the city's airport is forecast to hit 114 on Monday, but temperatures on the Strip could reach somewhere between 115 and 120 degrees.

Allen says the Las Vegas Strip's tall, close buildings and long stretches of concrete cause the area to heat quickly and cool slowly. She says it's hard to predict exactly how hot the Strip will get because the Weather Service does not get official readings there.

The Las Vegas-area is forecast on Tuesday to tie a record high of 117 degrees, last recorded in 2013.

An excessive heat warning is in effect as temperatures are expected to stay above 110 degrees into the weekend.

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GRAND CANYON

The National Park Service is warning visitors to Arizona not to hike into the Grand Canyon because of excessive heat.

Temperatures below the rim of the canyon are expected to reach as high as 117 degrees this week. Temperatures on the rim are expected to be in the low to high 90s.

If hikers do decide to go ahead with their planned trips, the Park Service says they should take extra precautions to avoid being overcome by the excessive heat. That includes hiking only before 10 a.m. and after 4 p.m. to avoid strenuous exertion during the hottest part of the day. Drinking extra water and sports drinks will help prevent dehydration that can trigger a health crisis like a heat stroke.

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