Human Exposure to Electromagnetic Fields

From Extremely Low Frequency (ELF) to Radiofrequency

Patrick Staebler

• Publisher: Wiley-ISTE
• Year: 2017
• Print ISBN:
  9781786301215
• eBook ISBN:
  9781119384526
• Edition: 1
• Topic: Scienze fisiche
• Subtopic: Elettromagnetismo

Everyone, whether they like it or not, is exposed to electromagnetic fields, most of the time, at very low levels. In this case, they are inconsequential, but they can cause adverse health effects when they become intense enough. This topic is complex and sensitive.

Covering frequencies from 0 Hz to 300 GHz, Human Exposure to Electromagnetic Fields provides an overview of this vast topic. After a reminder of the concepts of electromagnetic fields, the author presents some examples of sources of radiation in daily life and in the industrial or medical sectors. The biophysical and biological effects of these fields on the human body are detailed and the exposure limits are recalled. The exposure assessment and the implementation of the appropriate regulation within companies are also covered.

Technically and practically, this book is aimed at people with a scientific background, risk prevention actors, health physicians, especially occupational doctors, and equipment designers.

1
Concepts of Electromagnetic Fields

Electromagnetic fields are produced from natural and artificial sources. We distinguish between electric, magnetic and electromagnetic fields. Whether static or variable in time, they each have physical properties that produce specific interactions with biological organisms: plant, animal and human.

To provide a better understanding of the interaction mechanisms, the concepts of electromagnetism and the associated terminology are presented in this chapter [FEY 15].

1.1. Concepts of fields

1.1.1. Introduction

In physics, a field can be defined as an area of influence. We are immersed in the Earth’s gravitational field (the area within which the Earth attracts objects) and in electromagnetic fields (areas within which we can pick up television broadcasts and mobile phone signals, for example).

Gravity acts between two bodies that have a mass, while an electric field acts on positive or negative electric charges (electric charge is a fundamental property of matter, along with mass). These interactions are due to forces whose intensity is proportional to the mass of the objects or to the value of the electric charges. They decrease with the square of the distance that separates them and cancel each other out ad infinitum. The expression of these forces is identical. Their intensity in Newton (N) is given, respectively, by the law of gravitation and by Coulomb’s law (in classical physics):

• – law of gravitation between two masses m₁ and m₂:

[1.1a]

• – Coulomb’s law between two electric charges q₁ and q₂:

[1.1b]

where d is the distance in meters between the two objects, G is the universal gravitational constant, and:

Coulomb’s constant (N·m²·C^–2), and “c” is the speed of light (≈ 3 × 10⁺⁸ m·s^–1). ε_o is a constant that will be introduced later on. If we refer to the Earth, F_G1/2 represents the weight and [1.1a] becomes simply P = m·g with g = 9.81 m·s^–2.

Unlike the gravitational force, which always attracts objects, the electric force attracts opposite charges and repels them if they have the same sign. The force is directed according to the straight line between the two masses or charges.

Thus, the field is the area where forces can exert themselves remotely, without there necessarily being any propagation of matter or energy. Unlike electric fields, the Earth’s gravity has the advantage of being directly perceived by living organisms.

The concept of the field enables us to introduce physical (vectorial)¹ quantities, values associated with a unit, to quantify these phenomena and put them into an equation for the purposes of analysis and prediction.

The physical quantity associated with electric charges is the electric field.

1.1.2. Electric fields

The electric field is introduced into Coulomb’s law [1.1b] as follows:

[1.2]

E_1/2 is the electric field created by the charge q₁ in the place of q₂ (the symbol E is reserved for the quantity that is the electric field). An electric field appears as soon as there is an electric charge. Generally, knowledge of E makes it possible to calculate the force exerted on any charge.

In practice, an electric field is created by an inequality of charges between two distinct points. This inequality may be due to a difference in potential or volt...

Table of contents

• Cover
• Table of Contents
• Dedication
• Title
• Copyright
• Preface
• Acknowledgments
• 1 Concepts of Electromagnetic Fields
• 2 Sources of Electromagnetic Fields
• 3 Biophysical Mechanisms
• 4 Biological Effects of Electromagnetic Fields
• 5 Exposure Limits for Electromagnetic Fields
• 6 Exposure Indices
• 7 Applications of Exposure Indices
• 8 Exposure Assessment
• 9 Implementation of Directive 2013/35/EU
• Appendix 1: Equipment and Workplaces Classification
• Appendix 2: Weighting Filters
• Glossary
• Bibliography
• Index
• End User License Agreement