Variation of Microwave Leakage Exposure Levels Close to a Microwave Oven with Load, Container Type and Time.

Abstract

Nowadays people are living in a rush world and most people seek efficient methods to complete their day to day work with less time. Microwave ovens are the best option to cook foods as well as for reheating precooked foods. Microwave ovens use radio frequency (RF) electromagnetic waves around the frequency 2.4 GHz for cooking and reheating food by dielectric heating or high frequency heating. Many scientific reports have been confirmed that eating microwave food is not a risk, because radio waves cannot ionize foods. But the problem is exposing to the leakage microwave radiation when operating the oven. Authorized bodies such as International Commission on Non-Ionizing Radiation Protection (ICNIRP) as well as Federal Communications Commission (FCC) have been published limitations for exposure to these RF waves. The limited plane wave power density for a microwave oven is 50 W/m2 at any point 5 cm away from the oven. Over exposure to these RF waves with high plane wave power densities may lead to health effects such as cataracts in the eyes, infertility, and brain tumors. In this study, leakage microwave plane wave power densities were evaluated by using spectran HF6065 spectrum analyzer under three situations with newly brought microwave oven. In the first study variation of RF levels at 40 cm from the front glass of the microwave oven with the load (water) were evaluated, In the second study RF levels around the microwave oven for same load kept in plastic and ceramic containers were evaluated separately and, in the third study, time variation of the power density at a distance 40 cm in front of the microwave oven for a duration of 180 s was evaluated. Results in the first study show that negative correlation (r=-0.6136) between the load and leakage microwave emission around the oven as well as maximum average plane wave power density of (512.78 ± 0.01) mW/m2

with no load inside the oven and maximum average plane wave power density with the load is 195.06 ± 0.01 mW/m2 with 100 ± 1 g of load kept in a plastic container with mass 68 g. For the second study considerably low RF levels were recorded when using the ceramic container than plastic container. Results for the third study show that microwave emission around the oven is fluctuating rapidly with time and it can be varied between 0.01 mW/m2 and 108.48 mW/m2 . Evaluated maximum RF plane wave power density among all three studies was (677.84 ± 0.01 mW/m2 ) and this value is 1.35 % of maximum permissible leakage level for a microwave oven as well as it is found that frequency of the microwave radiation is also varying when it is operating. However, authors would like to request not to stay close to a microwave oven when it is operating, especially children and pregnant women because they are more sensitive for non-ionizing RF radiations.