Numbers in public health often tell a story more clearly than any argument. The number 96.6% is one of those numbers.

It comes from the US CDC's Traveler-based Genomic Surveillance (TGS) program, which ran from September 2021 through August 2024 and represents the most comprehensive published dataset on aviation wastewater surveillance in existence [1]. Specifically, it is the positivity rate for SARS-CoV-2 found in airport triturator samples — and understanding what a triturator is, and why pooling works this way, explains why aircraft wastewater surveillance is structurally superior to individual passenger screening.

What is a triturator, and why does it matter?

When an aircraft lands and taxis to its gate, a ground service vehicle connects to the aircraft's lavatory service port to empty the waste holding tank. At some major airports — JFK, Washington Dulles, and others in the TGS network — the waste from multiple aircraft is directed into a shared airport collection system that feeds through a triturator: a large industrial machine that grinds and mixes the pooled waste from many flights before it enters the sewage system.

From a surveillance standpoint, this is enormously valuable. A single triturator sample is not the wastewater of one aircraft — it is the wastewater of an entire airport's inbound traffic for a period of time. If SARS-CoV-2 is present on any of those flights, it ends up concentrated in that pooled sample. The probability of detection rises accordingly.

The TGS program found that 96.6% of triturator samples tested positive for SARS-CoV-2 [1]. Even individual aircraft samples — a much smaller pool — tested positive at rates above 80%. These are not close calls or borderline detections. They are clear, consistent signals.

Why individual swabs cannot match this

The clinical alternative — asking passengers to provide nasal swabs — has fundamental limitations that wastewater does not share.

Compliance is incomplete. Passengers who feel well, or who are traveling for business and wish to avoid delays, frequently decline voluntary testing. The TGS program found that enrolling travelers in nasal swab programs was logistically intensive, requiring dedicated staff and consent processes that created friction in the passenger flow.

Timing is wrong. Many infectious travelers are pre-symptomatic at the point of travel — they feel fine, their nasal swab viral load may be at its early-growth phase and below the detection threshold, yet they will be shedding more substantially within 48 hours. Wastewater captures what the nose may miss.

Scale is impossible. To screen 30,000 inbound passengers per day at a major hub like Suvarnabhumi using clinical swabs would require a workforce and laboratory capacity that no airport could sustain. Wastewater samples the equivalent population with a single collection event per aircraft.

The statistical equivalent. A 2024 study published in Frontiers in Environmental Health found that wastewater from 86 flights arriving in Israel detected SARS-CoV-2 in over 90% of samples even when the clinical infection prevalence among passengers was only 1.8% to 3.4% [2]. The wastewater was catching signal even when very few passengers were infected — because even a small number of infected individuals shedding into a pooled holding tank creates a detectable signal.

What the TGS program actually found

Beyond the headline positivity rates, the TGS report documents a number of findings worth understanding:

The program successfully transitioned from nasal swabs only (September 2021 to February 2023) to include aviation wastewater (February 2023 onward), and the wastewater data complemented the clinical data in important ways. Wastewater consistently detected respiratory viruses — including SARS-CoV-2, influenza A and B, RSV — as well as gastrointestinal viruses including norovirus, year-round, regardless of seasonal patterns.

The multi-pathogen detection is significant. It means the infrastructure, once built for COVID-19, becomes a standing platform for any pathogen of concern. When the next novel respiratory virus emerges from an international source, the same collection equipment, the same laboratory pipeline, and the same data reporting systems can detect it — without building anything new.

96.6% is not a measure of one virus at one airport. It is a measure of what becomes possible when you stop asking individuals to cooperate and start asking their biology to tell the truth.

Implications for airport design in Thailand

The TGS finding that triturator samples outperform individual aircraft samples has direct design implications for any new aircraft wastewater program. At Suvarnabhumi, which handles over 60 million passengers annually, a well-designed surveillance system would combine both levels:

  • Aircraft-level sampling on high-priority routes (specific origin countries of concern), using direct lavatory port connections to identify which incoming flight corridors carry risk.
  • Triturator-level sampling for ambient, continuous surveillance of the entire airport's inbound load — providing a daily population-level readout even when no individual aircraft is specifically flagged.

This two-tier architecture mirrors what TGS implemented and provides both sensitivity (triturator always positive) and specificity (aircraft-level identifies the source).