Anytime I see this cited, I summarily dismiss the entirety of the article in question.
Why? Because you know what produces formaldehyde? Humans do.
So does a leaf blower produce less formaldehyde than the mouth breather in the break room at work? More than a Taylor Swift concert? Can't tell without numbers... If you're just gonna say that leaf blowers should be banned because formaldehyde, are you also suggesting genocide?