## 1 Introduction  
The authors have been conducting research for the purpose of quantitatively grasping the actual conditions of radiofrequency (RF) electromagnetic field (EMF) exposure levels in daily life and investigating the optimal way of risk communication using monitoring data since 2019 [1; 2; 3; 4; 5]. Studies on monitoring RF EMF exposure levels have also been conducted in other countries, especially those of the European Union [6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22]. In our spot measurement, we measured the RF EMF exposure level from mobile phone base stations and broadcast transmission stations in Tokyo suburbs and regional cities and compared them with past measurement results [1; 2; 3]. It was confirmed that the RF EMF exposure levels from mobile phone base stations are about three times higher than those obtained from past measurements in both urban and suburban areas. However, they are sufficiently low compared with the Japanese radio wave radiation protection guidelines [23], with a median value of approximately 1/10,000 or less [1]. Additional spot measurements in dwellings have confirmed that owing to the widespread use of wireless local area networks (W-LANs), the RF EMF exposure levels from W-LANs are approximately 50% of the exposure levels from mobile phone base stations [4]. Measurements of RF EMF exposure levels in a wide area were also carried out in Japan and overseas by installing measuring instruments in a car [24; 25; 26; 27; 28; 29; 30]. Unlike spot measurements, the main advantage of measurements with a moving car is that RF EMF levels can be easily measured in a wide area. It has been reported [24; 25; 26; 27] that the transmitted power from mobile phone terminals was measured in a car. In particular, in [24; 26], the authors used a head phantom, which simulates the electric properties of a human head, to measure RF EMF levels in a situation similar to that during voice calls. In [25; 28; 29; 30], the authors measured RF EMF exposure levels from mobile phone base stations using an isotropic E-field probe. [PERSON] and [PERSON] reported their car-mounted measurements in Sweden at a frequency range of 30 MHz to 3 GHz using a three-axis antenna over a driving distance of 115 km [28]. One of the concerns from the viewpoint of RF EMF exposure is that it is difficult to obtain time-averaged exposure levels at the same point when driving. However, extensive amounts of measurements ensure that the median value is robust, as described in [28]. [PERSON] et al. investigated a method of predicting EMF exposure levels based on car-measured results [29]. [PERSON] et al. also studied the prediction using an artificial neural network (ANN) model with car measurements [30]. They carried out E-field measurements along a 65 km route in Paris to evaluate the prediction using the ANN. In Japan, [PERSON] et al. investigated the relationship between transmitted power from a mobile phone and electric field (E-field) strength from mobile phone base stations for the 4 th generation (4G) mobile phone system around Tokyo for about 8 h [25]. Since the power transmitted from a phone was the focus, only the frequency bandwidths allocated for one mobile operator were considered in the measurement of the E-field strength from the base stations [25]. In this paper, E-field measurements from May 2021 to February 2022 using a car driven within a radius of 100 km centered on Nihonbashi, Tokyo, which covers the entire areas of metropolitan Tokyo, Kanagawa, Saitama, and Chiba prefectures, and partial areas of Ibaraki, Tochigi, Gunma, Shizuoka, and Yamanashi prefectures are reported. The total measurement distance was about 13,000 km. In our measurement, the whole frequency range of mobile phone systems, including 5 th generation (5G) systems, FM broadcasting, and terrestrial digital TV broadcasting, was considered. Prior to the measurements, the measurement system installed in the car was evaluated in a large anechoic chamber. In addition to the above, there are three discussions, as follows.