The source for unknown chemical odors in laboratories is often unmaintained cup sink drains.

If sink traps are allowed to dry out, the relatively negative pressure of the laboratory draws air backwards through the drains. This air can be contaminated with chemical vapors from materials flushed down other sinks.

To avoid this, periodically run a few cups of water into sink drains or else if a sink will not be used, install a rubber stopper into the sink drain.

A few cups of water will also stop odors from coming back through floor drains. Please do not activate the safety showers to fill the drain traps under them.