Hazard

We mentioned last week how robotaxi provider Cruise was having a no-good, very bad week, after one of their driverless taxis picked a fight with a semi, and it was revealed that amorous San Franciscans were taking advantage of the privacy afforded by not having a driver in the front seat. It appears that we weren’t the only ones to notice all the bad news, since California’s Department of Motor Vehicles issued an order to the company to cut its robotaxi fleet in half. The regulatory move comes after a recent Cruise collision with a fire truck, which injured a passenger in the taxi. Curiously, the DMV order stipulates that Cruise can only operate 50 vehicles during the day, while allowing 150 vehicles at night. We’d have thought the opposite would make more sense, since driving at night is generally more difficult than during daylight hours. But perhaps the logic is that the streets are less crowded at night, whereas daytime is a more target-rich environment.

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A few years back, there were some studies on the chemical and particle emissions coming out of the hotends of 3D printers. Although they galvanized a lot of people in the community, the science wasn’t entirely conclusive — one paper made it sound like you needed a hazmat suit for 3D printing, and the other suggested that cooking a meal in a kitchen was worse for you. That’s because they were measuring different things.

This new research paper on the emissions of 3D printers covers all the bases. They examined a variety of different materials printed in different printers. They also measured both chemical emissions and Ultrafine Particles (UFP) which can be hazardous even when the material itself is not.

We read the paper (PDF) so that you don’t have to. Here’s our takeaways:

There was no significant variation across brands of 3D printers. (Duh?)
ABS and similar materials outgas styrene at levels you should probably be worrying about if you’re running your printer for a few hours a day in an unventilated office.
PLA emitted significantly less overall, and most of it was a non-hazardous chemical, lactide. PLA doesn’t look like a problem.
All of the materials resulted in increased UFP exposure. These levels are above normal household background levels, but lower than certain “microclimates” which (if you follow the references) include principals’ offices with carpet, automobiles, restaurants, and rooms with burning candles or running hair dryers. In short, the UFP exposure doesn’t look like it’s going to be a big deal unless you’re sitting right next to the printer and running it continually.

So what would we do? It now looks like it’s prudent to print ABS only in a well-ventilated room. Or enclose the printer in a box and vent whatever you can outside — which can also help prevent breezes cooling the piece down unevenly and adding to ABS’s warping problems. Or just stick to PLA. It looks essentially harmless.

Thanks [Jim Scheitel] for the tip!