Dark Room Usage

Establishing Dark Room Expectations across WashU Medical Campus

Issued: February 2026

Definitions:

Dark Room

A research or technology space designed to limit ambient light to support light-sensitive equipment, experiments, or imaging workflows.

Light-Sensitive Research Area

A space where exposure to ambient light could compromise active experiments, imaging, or data integrity OR where lighting levels may be adjusted by user preference to enhance image fidelity and reduce eye strain.

Occupancy Indicator

A manually operated slider or sign mounted at the room entrance indicating whether the space is occupied or unoccupied.

Curtain System

Blackout curtains or similar physical barriers used to control light exposure within dark rooms.

Purpose:

This document establishes standardized naming conventions, signage, and behavioral expectations for the use of dark rooms across WashU Medicine. The goals of these guidelines are to:

  • Protect light‑sensitive research and equipment
  • Reduce unintentional research disruption
  • Minimize interpersonal risks associated with uncoordinated entry
  • Promote consistent, campus‑wide expectations for shared sensitive spaces

Scope

These guidelines apply to all microscopy rooms, imaging suites, and other designated dark rooms across the WashU Medicine campus, regardless of department or funding source. All users are expected to comply with posted signage and occupancy controls.

Dark Room Requirements:

Occupancy Indicator Requirement

Each dark room must be equipped with a manual occupancy indicator mounted at eye level outside the room entrance.

Standard Indicator States:

  • UNOCCUPIED / SAFE TO ENTER
  • OCCUPIED / DO NOT ENTER

Users are responsible for updating the occupancy indicator upon entering and exiting the space. Failure to use the indicator undermines shared safety and research integrity.

Entry and Use Expectations
  • Users must check the occupancy indicator before entering any dark room.
  • Entry into a Single‑Occupant Dark Room is prohibited while marked occupied.
  • In Multi‑Occupant Dark Rooms, users must announce entry and coordinate with existing occupants prior to opening doors or moving curtains.
  • Uncoordinated entry may disrupt research and create safety or interpersonal concerns.
Curtain Management

To prevent inappropriate dark room conditions and reduce misuse:

All curtains must be fully OPEN when:

  • No equipment is running and
  • No researcher is physically present in the room
  • Curtains may only be closed during active research or imaging activities.

This requirement applies to all dark rooms without exception.

Quick-Use Guidelines (Posted at Each Location)

Each dark room must display a brief, visible summary of expectations near the entrance, including:

  • Check the occupancy indicator before entering
  • Do not enter occupied areas as designed by occupancy indicator
  • Coordinate entry in subdivided light sensitive research areas per provided room plan
  • Open assigned space curtains when the room is unoccupied and no equipment is running
  • If all curtains are open, signifying the room/space is vacant, reset the occupancy indicator to “Unoccupied” when leaving

Additional Information and Governance

This guideline is maintained as an evergreen document and may be updated as space configurations, technologies, or campus needs evolve.

Questions, concerns, or requests for clarification should be directed to the appropriate building operations or facilities management team.

Last Updated: January 2026