Abstract
SIR—The Tempa.Dot single-use thermometer has been in use in the UK for over 10 years and in the USA for nearly 30 years. Over the last 7 years it has been marketed by 3M Health Care Limited. Its use in the NHS followed the European Union Directive to reduce the medical use of mercury. It also has the advantages of lack of cross-infection risk and more rapid recordings. A sensor matrix at the tip of the thermometer consists of 50 temperature-indicating dots, each with a melting point separation of 0.1 °C. At any given temperature within the range 35.5–40.4 °C, all dots with a melting point at or below that temperature change colour from beige to bright blue. Temperature readings are indicated by the number on the thermometer that corresponds with the row of the last blue dot plus 0.1 °C for every blue dot in that row greater than one. Tempa.Dot complies with European published standard EN-12470- 02(P2). This requires the mean accuracy to be within 0.1 °C for each dot