Insurance companies and defense lawyers often bring this up to argue that a sickness showed up too long after an exposure to be connected, or that the person should have known about the problem earlier. What it really means is the span of time between contact with a harmful substance, condition, or event and the point when symptoms, disease, or measurable harm appear. With chemicals, asbestos, mold, contaminated water, or job-related exposures, that gap can be months, years, or even decades.

That delay matters because people usually do not file a claim the day they breathe in dust or touch a toxic substance. They file when they become sick and learn there may be a link. In a lawsuit, the latency period can affect causation, medical proof, and the deadline for filing under the statute of limitations. Experts may be needed to explain why a disease appeared long after the exposure and why that timing still fits the science.

In New York, latent injury claims are affected by CPLR 214-c, which ties the filing period to discovery of the injury rather than the original exposure in many toxic tort cases. But if a public agency is involved, separate rules may apply. Claims against entities like the MTA or a city agency can require a notice of claim within 90 days, so timing can get complicated fast.