New York is a city of restaurants. More than five million people go out for a meal at least once a week. And there are around 24,000 eateries in the five boroughs, all of which, in theory, should have a letter grade in the window or posted on the door indicating some level of cleanliness and health. These days, that grade is almost always an A.

If you’ve ever wondered how those grades get handed out, it’s not all backroom dealing. For the past five years, New York City’s health department has had another tool at its disposal: Yelp. That’s right. If the city sees that two or more people, within a month, have posted a nasty review with words like “sick,” or “vomiting,” or “diarrhea,” they’ll open an investigation into that restaurant. And sometimes, that leads to a health code violation.

Since 2012, the department has investigated approximately 28,000 complaints of “suspected foodborne illness” in the city. Of those complaints, over 8,000 of them came from Yelp. And since November 2016, it’s been scraping Twitter, too.

The fact is, while the city’s health department relies on calls or online submissions to its public hotline, more and more the department is scraping Yelp for information about public health issues, like food poisoning.

Read the full article on Yelp by Sam Bloch at The New Food Economy