Great question. Short answer from the Red Cross and Mayo Clinic: (1) Contact 911 first (2) Begin immediate cooling by any method including removing them from th

Great question. Short answer from the Red Cross and Mayo Clinic: (1) Contact 911 first (2) Begin immediate cooling by any method including removing them from the hot environment, removing their clothing, and applying cold water immersion or cold water on skin with fanning and (3) transfer to hospital while continuing to cool Details: The American Red Cross in their current guidelines available at https://cpr.heart.org/en/resuscitation-science/first-aid-guidelines/first-aid https://cpr.heart.org/en/resuscitation-science/first-aid-gui... and https://doi.org/10.1161/CIR.0000000000000900 https://doi.org/10.1161/CIR.0000000000000900 advise that “For adults and children with exertional hyperthermia or heat stroke, first aid providers should move the individual from the hot environment, remove excess clothing, limit exertion, and activate emergency services. For adults with exertional hyperthermia or heatstroke, it is reasonable to initiate immediate active cooling by using whole-body (neck down) cool- to cold-water immersion techniques (1°C–26°C [33.8°F–78.8°F]), when safe, until a core body temperature of <39°C (102.2°F) is reached or neurological symptoms resolve. For children with exertional hyperthermia or heatstroke, it may be reasonable to initiate immediate active cooling by using whole-body (neck down) cool- to cold-water immersion techniques (1°C–26°C [33.8°F–78.8°F]), when safe, until a core body temperature of <39°C (102.2°F) is reached or neurological symptoms resolve.” From this we can conclude you might reasonably cool those suffering from heat stroke yourself within the generally-accepted first aid standards or scope of practice (in fact, the Red Cross/AHA use the language should for their active cooling recommendations in some summaries). You would want to have a way of checking the patient’s temperature to cease cooling interventions when it reaches 102.2°F (other sources advise stopping if the patient begins to shiver). This recommendation was added in 2020, the most recent guideline update. The fancy interventions that paramedics and advanced prehospital clinicians can administer include IV fluid replacement, anticonvulsants, and intubation (cf. https://emcrit.org/ibcc/hyperthermia/ https://emcrit.org/ibcc/hyperthermia/) and the ambulance has a/c and potentially other cooling devices. Also there is a possibility for cardiac failure https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8843991/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8843991/ so all providers should be prepared to initiate CPR and EMS has tools for cardiac monitoring and support/resuscitation.