Question

ozone - depleting chemicals
in the mid - 1900s, ozone - depleting chemicals like cfcs, hcfcs, and halons were widely used worldwide. they were considered revolutionary for applications such as air conditioning and refrigeration. these compounds, present in appliances and fire extinguishers, had long - term effects. however, as these products aged or were discarded, the chemicals were released into the atmosphere. millions of people unknowingly contributed to this release by repairing or disposing of appliances. the substantial environmental impact led to global initiatives to regulate and ultimately phase - out these substances.
in the mid - 1900s where were ozone depleting chemicals used?
worldwide
only in hot climates
only in the us

Explanation:

The text says "Ozone - depleting chemicals like CFCs, HCFCs, and Halons were widely used worldwide". There is no indication that they were only used in hot climates or only in the US. The word "widely" implies a large - scale, global (worldwide) usage.

Answer:

worldwide