The Yellow Whistle is more than a dollar’s worth of molded plastic.

It’s a safety device for Asian Americans, who have been attacked on city streets from Philadelphia to San Francisco.

It’s a symbol of hope, the color of spring daffodils — and a reminder that yellow has been the hue of American xenophobia, used to raise the false threat of “Yellow Peril.” And it’s a call for people to join and sound an alarm against rising anti-Asian violence.

“It’s an easy way for people to get involved, to have something to hold on to,” said Alix Webb, executive director of Asian Americans United, among the local organizations that are distributing whistles. “It’s a very hard moment, but it’s also a moment to build on.”

AAU civic-engagement coordinator Wei Chen likes the functionality and symbolism. “Whistle-blowing is getting attention, attention from the public to the needs of the Asian community and the immigrant community.”

The Yellow Whistle project wasn’t supposed to get this big. The founders — including the Lansdale mother of an adopted Chinese daughter — expected to hand out a few thousand. Six weeks later, they’ve distributed nearly 200,000 nationwide and plan to give away at least 200,000 more.

“This whole ‘othering’ of Asian Americans is something that needs a collective response,” said Anne Martin Montgomery, a community activist whose daughter has been harangued on the subway while attending school in New York.

Anyone can have a whistle. In fact, the more people who wear one in solidarity, the better, organizers said.

The Philadelphia Chinatown Development Corp. has been giving out whistles, along with the Korean American Association of Greater Philadelphia, SEAMAAC, Penn Asian Senior Services, the Pottstown NAACP, and Pennsylvania Hospital.

Each whistle comes attached to a coiled wrist cord, not a lanyard. That’s deliberate, because a lanyard could wrap around the neck if grabbed by an assailant.

And assaults against Asian Americans are continuing to increase.

Hate incidents increased 194% in the first quarter of 2021 compared with the same period a year ago in 22 big U.S. cities and counties, according to new data from the Center for the Study of Hate & Extremism at California State University, San Bernardino. The total number of incidents filed to police increased from 36 to 106, though many or most go unreported to authorities.

People have been kicked, punched, and harassed by shouts of “Go back to China!” Some have been severely injured and hospitalized.

Stop AAPI Hate, a coalition of nonprofits, organizers, and educators that operates an online, multilanguage reporting center, was notified of 6,603 incidents from March 2020 through March 2021, including a huge surge in that final month. Verbal harassment accounted for 65%, and 13% were physical attacks.

In Philadelphia, the official figure tripled between 2019 and 2020, from eight to 28. Two 17-year-old Indonesian girls were pushed, slapped, and punched on the City Hall subway platform in March, and Chinatown saw two assaults in three days in April.

Former President Donald Trump stoked pandemic hatred — the fatal shooting of six Asian women in Atlanta came on the one-year anniversary of his first “China virus” tweet. But as society reopens, some Asian Americans are more worried, not less, as their return to jobs, schools, and transportation systems increases their exposure.

Last month, volunteer safety ambassadors took to Philadelphia Chinatown streets, hoping their night patrols would deter hate crimes and offer residents a greater sense of safety. Dozens of people signed up for free self-defense classes taught by the Philadelphia Wing Chun Kung Fu School.

The Yellow Whistle campaign sprang from a horrific March 29 incident captured on a security camera in New York City. As a 65-year-old Filipino immigrant walked near Times Square, a man kicked her in the stomach and then, as she fell, kicked her in the head again and again, shouting, “You don’t belong here!”

“All of us were very upset,” said Agnes Hsu-Tang, an archaeologist and distinguished consulting scholar to the Penn Museum.

A friend texted her: “Enough is enough. We have to do something.”

They considered different ideas. Personal-alarm systems could be complicated for seniors. Laws made it hard to buy pepper-spray canisters in bulk.

Hsu-Tang, known in the Chinese-language press as “China’s Laura Croft,” thought about her work in central-Asia deserts, particularly the Taklamakan desert in China. She always carries a whistle. It’s a way to signal if she gets lost or cut off from the group.

For this crisis, she thought, a whistle would be perfect. It doesn’t need batteries. It has no language barrier. It can’t be turned against the victim, like pepper spray. And if an assailant tears at the wrist coil, it comes off.

“I said we should make it a yellow whistle,” said her husband, Oscar Tang, a financier who is cochair of the New York Philharmonic. “To reappropriate it, against anti-Asian hate and the violence.”

Hsu-Tang grew up in Taiwan, immigrating with her family to Washington, D.C. Tang was 11 when his parents sent him to the United States, having fled from Shanghai to Hong Kong in late 1948 as Mao’s communists took over China.

Every Yellow Whistle is stamped “We belong,” a response to racist views of Asians as never being fully American.

“We belong as much as anybody,” Tang said. “This is a defining moment for Asian Americans to begin to stand up.”

The project founders tell people: Always keep the whistle on your wrist. If you’re in danger, blow the whistle. If you hear a whistle, call 911. Share social-media messages with the #theyellowwhistle hashtag, but don’t share your whistle — the coronavirus still circulates.

So far, founders say, they haven’t had any reports of someone using the whistle to signal an attack.

Organizations that want deliveries of whistles can place requests on the website www.theyellowwhistle.org.

The first Yellow Whistles went to groups that serve the elderly in New York Chinatown, and then to more than a hundred organizations across the country: neighborhood watches, legal services, colleges, libraries, hospitals, historical societies, civic groups, and adoption programs. The orders haven’t stopped coming.

“We’re literally and symbolically whistle-blowing on racism,” Hsu-Tang said. “We want to make sure they hear it.”