Two still working. One continuously since 2009 purchase.
These were amazing bulbs! No Question.
They did improve the air quality too for a long time, but
no where as long as the bulbs have lasted due to the element
likely getting clogged pulling in and circulating the air
while attracting particles in the air.
Thanks for asking. Im surprised any one remembered I tested them.
Of the four bulb pack I bought, the two that went down were
replaced with more current LED Bulbs that draw a trickle of power
while providing a very nice color of white light.
If the ZEVOTEK Bulbs returned as an LED w/Air Purifier... hmmmmmm
Who knows what that could generate in sales making people happy.
Cheers, Friend