Sievert Nuclear Regulatory Commission permits the use of the units curie, rad, and rem alongside SI units, the European Union European units of measurement directives required that their use for "public health ... purposes" be phased out by 31 December 1985. An older unit for the dose equivalent is the rem, still often used in the United States. One sievert is equal to 100 rem: Sievert The sievert (symbol: Sv) is a derived unit of ionizing radiation dose in the International System of Units (SI) and is a measure of the health effect of low levels of ionizing radiation on the
Samut Prakan radiation accident symbol. Although the symbol was displayed on the teletherapy head, none of those handling the device were aware of its meaning, nor were there written warnings in Thai. Together with the International Organization for Standardization (ISO), the IAEA developed a new symbol that would serve as an intuitive warning for large sources of ionizing radiation. The new symbol was published in 2007 as ISO 21482, and is intended to accompany the trefoil on internal components of devices containing dangerous sources to prevent persons from unknowingly disassembling them. In Thailand, however, substantial efforts to prevent further such occurrences had not materialized