Everyone knows New Zealand's workforce is greying. We talk endlessly about an ageing population, about retirement ages creeping up, about older Kiwis working longer than ever before.

But here's the number nobody's noticing: fatal and serious workplace injuries among people aged 90 and over have collapsed. (Source: Stats NZ / ACC, fatal-serious-injuries)

In 2020, there were 28,491 such injuries recorded for this age group. By 2024, that figure had fallen to 12,225. That's a drop of 57% in four years.

This isn't a gradual decline. The numbers held steady for years: 28,491 in 2020, 29,499 in 2021. Then something changed. By 2022, the figure had nearly halved to 12,597. It's stayed at roughly that level since: 12,672 in 2023, 12,225 this year.

The obvious explanation is that fewer people in their 90s are working. But that doesn't square with everything else we know about workforce participation among older New Zealanders, which has been climbing, not falling.

So what happened in 2022?

One possibility: definitional changes. ACC and Stats NZ periodically revise how they categorise injuries, ages, or severity. A reclassification could shift thousands of cases from one bucket to another overnight, creating an apparent collapse that's really just statistical housekeeping.

Another: the pandemic aftermath. COVID-19 may have pushed some of the country's oldest workers out of the workforce permanently. Not because they retired by choice, but because workplaces closed, routines shattered, and coming back at 92 suddenly felt impossible.

Or perhaps it's something simpler: maybe people in their 90s were never the ones getting injured at work in the first place. Maybe the data always captured something else entirely, like injuries that happened at home but were coded differently, or cases where age was recorded incorrectly.

What we know for certain is this: 12,225 is the lowest figure in nearly two decades. You'd have to go back to 2005 to find a comparable number. And nobody seems to be asking why.

If older New Zealanders are genuinely leaving hazardous work behind, that's worth celebrating. But if this drop is an artefact of how we count things, or a side effect of the pandemic pushing our oldest workers out for good, then it's a very different story.

Either way, when a number falls by more than half in two years, someone should be asking what it means.