<human>: Is "In 1999, a study of the effect of washing on the formaldehyde levels found that after 6 months after washing, 7 of 27 shirts had levels in excess of 75 ppm, which is a safe limit for direct skin exposure." a good answer to the question "How many months of washing did a 1999 study look at?"
OPTIONS:
- yes
- no
<bot>: yes