Labor economist says subtle heat effects on workers cost the economy trillions of dollars a year

The only dose-response figure in Park's account concerns students. He examined more than four million New York City public school test scores and found that a student sitting an exam on a 90 degree day was roughly 10% less likely to pass the subject than on a 70 degree day ^[8]. Put a hundred students who would have passed in 70 degree weather into a 90 degree room, and about ninety pass ^[12]. Park said the subtle hazards he studies do trillions of dollars of damage every year ^[7]. That figure comes without a breakdown ^[16].

For an operator, the useful detail is the temperature. Park said nobody is going to write about a 92 or 93 degree day, but that there are many more of these days ^[5]. A policy that activates on a heat advisory is keyed to the days that do get written about. He also said both hot and cold temperatures can negatively affect worker productivity ^[13], so a summer-only plan covers only one side of that.

Park described more people falling off ladders, more workers getting hit by cranes, and more workers dropping big pieces of machinery on someone else ^[9]. Those are coded as ordinary industrial accidents. He also said accidents appear to rise on hot days indoors, and on the reason, he said: "We're not sure." ^[10]

An employer that scoped heat risk by job title, outdoor crews first, drew a line the injury pattern Park describes does not follow, and drew it without knowing what the indoor pathway is ^[10].

This is one economist in a university interview, with no per-degree injury estimate and no firm-level cost, and a shift roster cannot be rebuilt on that. What survives is narrower: on Park's evidence the risk is not confined to advisory days ^[5][6], and it is not confined to outdoor work ^[10]. Both propositions are testable against data most employers already hold, since incident dates and site temperatures both exist.

The decade question here is capital. Air conditioning, shade, where work physically happens: Park tied exam outcomes partly to whether a student's home and school have air conditioning ^[15], and buildings are slow and expensive to change. The quarter question is smaller and comes due in June. Which crane picks, roof work and ladder jobs land on the warm afternoons, and whether a supervisor has any authority to move them. Park said fewer people are aware of these effects than of the headline disasters ^[11].