Women stood in line at a Mexico City subway entrance recently, but not to buy tickets. They were receiving whistles from authorities in an effort to combat rampant sexual harassment.
Some 15,000 plastic whistles were being handed out this week by the city as part of its "Live Safe" campaign in a capital where many women complain about men pawing them in public, or worse.
The metro, with 5.5 million passengers packed tightly in trains, is ground zero for many of these cases, despite the existence of subway cars reserved for women only.
The whistles aim to "end silence (about sexual assaults) through noise. It's an issue for everyone for women to live in peace in public transport," said Patricia Mercado, a top city government official.
Mayor Miguel Angel Mancera was mocked on social media when he announced his plan in May, with the hashtag #ElPitoDeMancera (#Mancera's Whistle) on Twitter.
Critics said it left security in the hands of women, but Mancera defended his measure, and said the criticism helped to put a spotlight on the problem of sexual assaults. Angelica Hernandez, a 30-year-old psychologist wearing a blue skirt and sweater, eagerly waited in line to get one of the whistles at the crime-riddled Pantitlan metro station.
She recalled being in a packed metro car one day when she was touched on her "private parts".
"I would hope that the authorities would show up" when someone uses the whistle, Hernandez said, complaining that the "authorities often don't act" before she entered the crowded station.
Remedios Ramirez, a 35-year-old metro station cleaner, said "nobody pays attention" when women call for help in public spaces.
"But if I make noise with the whistle, maybe I would get more attention and I would get help," Ramirez said.
Some 1,800 acts of public sexual abuse were reported in the capital last year, with a quarter of them taking place in the subway, according to an official survey. But the figure could be much higher as such cases often go unreported.
The city government said that three-quarters of investigations of sexual assault were related to subway incidents between January and March.
"It has to do with the way societies are structured in which it is established that women have less value," said Margarita Argott, coordinator of transport safety at the city government's Women's Institute. The capital has implemented other measures in the past to make women feel safer.
Metro officers were deployed in April and given pink vests as part of efforts to protect women.
Above ground, a fleet of pink taxis driven by women roams the streets.
Maria Consuelo Mejia, director of the Catholics for the Right to Decide group, spoke of a "grave" problem of sexual harassment in the city.
"In what world are we living when we have to separate women from men (in subway cars) so that they're not attacked?" she asked.
"The (whistle) alone is useless. But it is useful as a complementary measure that creates awareness about this issue."