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There’s a deadly heatwave sweeping through Japan right now.

By the latest count, more than 30 people have died this month from heat exhaustion or strokes due to temperatures as high as 105.26 ºF (40.7 ºC). Another 10,000 people have been hospitalized. In an attempt to prevent further death and injury, the Japanese government has stepped up its efforts to warn people of extreme heat.

In addition to launching school campaigns, a new smartphone app, and English-language resources, it has made a crucial information visualization update designed to benefit the oft-neglected color-blind population.

The Ministry of Environment’s Wet Bulb Globe Temperature (WBGT) index, which gives citizens a daily color-coded predictor of their location’s temperatures, currently marks heat stroke danger zones with the color red, and safe zones with the colors blue and green. But this can cause confusion for people who have color vision impairments. For instance, for those who have trouble seeing the color red, the index and color scale appear like a mess of mustard and brown hues.

An estimated 3 million Japanese—5% of men and 2% of women—have some form of colorblindness or shikikaku ijo. Japan’s Ministry of Environment announced on Wednesday (July 18) its plans introduce new colors to its heat map index next year, specifically for the purpose of making sure these people are getting the right information, at-a-glance.

Ministry of the Environment Government of Japan. How the current Heat Index looks to a person with perfect color vision.

Quartz How people with red-green colorblindness (deuteranopia) sees the index, generated with Adobe Illustrator’s Color Blind Proof Setup Mode.

The Ministry tells Quartz (via the Japan Foreign Press Center) that color updates will be revealed to the public in March and take effect when the 2019 WBGT index goes live next April. Because tens of thousands of people already refer to this year’s map, it would be risky to change it now.

As Tokyo prepares to host the 2020 Olympics and Paralympics, The Ministry of Environment is not the only Japanese institution evaluating the accessibility features of their physical and online infrastructure. The Japan Ministry of Economy, Trade and Industry recently updated the Japanese Industrial Standards with new color standards for making safety signs. The new standards are designed “to support people whose color visions vary, as well as overseas visitors in Japan.”

Ministry of Economy, Trade Color rules: Japan Industrial Standard, April 2018.

Japan’s acuity with color blindness

See 74?: The Ishihara Test

It may have taken the Environment Ministry 12 years to tweak its heatwave index for accessibility, but Japan has long been particularly attuned to colorblindness. Until 2003, public school students in Japan were tested for colorblindness as part of their routine eye exam. In 1916, army doctor Shinobu Ishihara invented the most widely used color perception diagnostic called the “Ishihara test.” The system of dots with subtle tonal gradations originally included hiragana characters, instead of numbers.

A controversy regarding colorblindness even rocked the Japanese imperial family. In 1920, Yamagata Aritomo, then an army field marshal, opposed then crown prince Hirohito‘s engagement to Kuninomiya Nagako (later Empress Kōjun) because she had relatives who were known to be colorblind. Yamagata, who would later become prime minister, said that Princess Nagako family’s color vision impairment could taint the imperial family’s lineage. Though he failed to foil the marriage, Yamagata’s color-blind discrimination case had a lingering effect in how Japanese see people with color deficiencies.

“Discrimination against people with color vision deficiency was strong back then (in the 20th century),” explains ophthalmologist Kaoru Nakamura, to Japan Times. “Marriages were annulled, job applications were rejected and people were turned away from almost every college science course in the country.” Indeed a 1986 survey found that majority of national universities barred colorblind applicants from enrolling in dentistry, education, and engineering.

Color tools for designers

The government’s heat map designers aren’t totally to blame for the oversight. They were likely following a long-held convention in heat-map design that is based on color associations: using red-orange to symbolize heat and blue-green to symbolize cool weather. “The challenge was to find new heat map colors that would be legible to the most common type of color blindness (deuteranopia), but still retain the intuitive warmer-as-it-gets-watched-more analogy,” designer Joe Ringenberg explains on the Wistia blog.

Ringenberg proposes a new spectrum that communicates to people with all types of color vision acuity.

Wistia Designing for all.

The most popular professional drawing tool, Adobe Illustrator, even has a built-in colorblindness inspector. The Color Blind Proof Setup Mode, implemented in 2009, allows graphic designers to preview their work in the same way a red-green colorblind individual would see it.

Quartz Color Blind Proof Setup Mode in Adobe Illustrator

There are many tools (here, here and here), browser plug-ins, and useful tutorials to help designers better serve the world’s 300 million users with color vision impairments, but perhaps the issue would be best addressed by making colorblind-accessible design a standard—like the Japanese are doing—instead of an afterthought.