Longevity of Viral Viability on Common Indoor Surfaces

Problem Statement

This experiment measures how long a virus remains infectious on everyday indoor materials under normal indoor temperature and humidity. It tests surface persistence directly, without assuming transmission pathways or behavioral implications.

Hidden Assumption Being Tested

Viruses deposited on typical indoor surfaces lose infectivity within a short time window (often assumed to be less than 24 hours).

What Might Be True Instead

Some viruses may remain infectious on certain indoor surfaces for 24 hours or longer under standard indoor conditions.

Minimal Experimental Setup

• Surfaces: stainless steel, polypropylene plastic, glass, painted wood, cotton fabric
• Coupon size: 2 × 2 cm
• Virus: standardized non-pathogenic BSL-2 surrogate
• Environment: 22 °C ±2 °C, 45% ±5% RH
• Time points: 0, 1, 4, 8, 24, 48, 72 hours
• Replicates: triplicate per surface per time point

Measurement Method

Virus is eluted from surfaces using standardized buffer and quantified using plaque assay or TCID₅₀. Results are reported as infectious titer.

Binary Kill Condition

• Pass: No detectable infectious virus on all surfaces at or before 24 hours.
• Fail: Infectious virus detected on any surface at 24 hours or later.

Controls & Confounders

• Positive control: viral stock viability
• Negative control: uninoculated surfaces
• Confounders: drying time, inoculum volume, surface cleanliness

Safety & Ethics

Conducted in certified BSL-2 laboratories. No human or animal testing.

Why This Matters

Persistence beyond assumed timelines would invalidate common surface hygiene assumptions and affect cleaning interval guidance in shared spaces.