技術レポート騒音計（サウンドレベルメータ）とは 15

The main laws related to noise pollution in our country and their contents are as follows. Based on these, government ordinances and regulations are established, and supervisory agencies each have their jurisdiction. In practice, pollution-related matters are handled at the 'Pollution Control Division' or 'Environmental Health Division' or 'Citizen Life Division' of each prefecture and municipality, while labor safety and health issues are managed by the labor standards inspection offices of each prefecture and the national government.

Basic Environmental Law (Environmental Standards) (Ministry of the Environment)
- Standards for Environmental Noise
- Standards regarding aircraft noise.
- Standards regarding Shinkansen railway noise.
- Standards for Noise from Conventional Railways
Noise Regulation Law (Ministry of the Environment)
- Standards for Noise from Specific Facilities and Factories
- Standards for Specific Construction Work Noise
- Standards for Automobile Traffic Noise and Automobile Noise
- Late-night operations and noise related to loudspeakers (standards are based on municipal regulations).
Environmental Impact Assessment Law (Environmental Assessment Law) (Ministry of the Environment)
Fire Service Act Enforcement Regulations (Ministry of Internal Affairs and Communications, Fire and Disaster Management Agency)
- Standards for alarm sounds and similar.
Labor Safety and Health Regulations (Ministry of Health, Labour and Welfare)
- For noise measurement in the work environment (Labor Safety and Health Regulations), please refer to this page from the Ministry of Health, Labour and Welfare.
- For the "Guidelines for Noise Prevention" (Revised in April 2023), please refer to this page of the Ministry of Health, Labour and Welfare.
Large-Scale Retail Store Location Law (Ministry of Economy, Trade and Industry)

The Basic Environmental Law was revised in April 1999, and part of the Noise Regulation Law was revised in April 2000. Additionally, the Environmental Assessment Law came into effect in June 1999.

Furthermore, the "Recommendations on Permissible Concentrations" published by the Japan Society for Occupational Health establishes "permissible noise standards" aimed at serving as a guide to prevent health disorders among workers due to environmental factors in the workplace.

In our country's Basic Environmental Law, it is stipulated as a desirable standard to be maintained for the protection of human health and the preservation of the living environment, setting a goal for the implementation of policies regarding to what extent air, water, soil, and noise should be maintained.
Based on the provisions of Article 16, Paragraph 1 of the Basic Environmental Law, it has been announced regarding the environmental standards related to noise, as a desirable standard to be maintained for the preservation of the living environment and the protection of human health, and it has been implemented since April 1, 1999.
This can be considered as the improvement target for environmental pollution caused by noise, namely the noise prevention target. Other standards such as "Environmental Standards Related to Aircraft," "Environmental Standards Related to Shinkansen Railways," and "Guidelines for Noise Control in the Case of New Establishment or Large-Scale Improvement of Conventional Railways" remain unchanged from before. For details, please refer to this law.

Table 13-1: Areas Other Than Those Facing Roads

Types of Regions	reference value
Types of Regions		daytime	nighttime
AA	50 decibels or less	40 decibels or less
A and B	55 decibels or less	45 decibels or less
C	60 decibels or less	50 decibels or less
The environmental standards shall be as listed in the column of standard values in the following table, categorized by region type and time division, and the regions to which each type applies shall be designated by the governor of the prefecture. The division of time is defined as daytime from 6 AM to 10 PM, and nighttime from 10 PM to 6 AM the following day. The areas where 'AA' is to be applied are those regions that require tranquility, such as those where medical facilities and social welfare facilities are gathered and established. The area designated for A is exclusively for residential use. The area to which B is applied is primarily designated for residential use. The area designated for C shall be one that serves a considerable number of residences along with commercial and industrial uses.

Table 13-2: Areas Facing the Road

regional classification	reference value
regional classification		daytime	nighttime
An area within A that faces a road with two or more lanes.	60 decibels or less	55 decibels or less
Area B, which faces roads with two or more lanes, and Area C, which faces roads with lanes.	65 decibels or less	60 decibels or less
A lane refers to a strip of roadway that has a certain width necessary for a line of automobiles to travel safely and smoothly.

Table 13-3 "Spaces Adjacent to Roads Serving Main Transportation Routes" (Special Case)

reference value
daytime	nighttime
70 decibels or less	65 decibels or less
When it is recognized that a household primarily lives with the windows closed on sides that are susceptible to noise, the standards for noise penetrating indoors can be applied (45 decibels or lower during the day, and 40 decibels or lower at night).

The criteria values of the above environmental standards shall be those determined by the following evaluation methods.

The evaluation is fundamentally based on the noise levels that affect individual residences, and it will be assessed based on the noise levels at the surfaces of buildings that are susceptible to noise. In this case, regarding the standards for noise penetrating indoors, the evaluation will subtract the sound insulation performance value of the building from the noise level at the susceptible surfaces.
The method for evaluating noise is based on the equivalent noise level, and it is principled to assess it through the equivalent noise level over the entire duration of each time segment.
The timing of the evaluation will be determined by selecting days when the noise presents an average situation throughout the year.
When conducting measurements for evaluation purposes, the noise level measurement methods specified in JIS Z 8731 should be used as a principle. If the influence of reflections from the building cannot be ignored, measurements should be taken at a location where this can be avoided; if this is difficult, appropriate measures such as correcting the actual measured values should be taken. Furthermore, if the necessary measurement time cannot be secured, it is permissible to estimate the noise level based on conditions such as road traffic volume instead of direct measurement.
Furthermore, locations that generate significant noise, such as factories and business establishments, construction sites, airports, and railway premises, as well as similar places, are to be excluded from the measurement locations.
These environmental standards shall be exempt from application to aircraft noise, railway noise, and construction work noise.

For areas not facing the road, it is generally required to select and evaluate locations that are considered representative of the noise in those specific areas.
For areas facing roads, the evaluation shall be conducted by grasping the number of residences that exceed the standard value of "1." of the environmental criteria and the proportion of those exceeding it, in principle, for each defined region.

Table 13-4: Aircraft Noise

Types of Regions	Reference value (WECPNL) below dB
An area exclusively used for residential purposes.	70
Areas outside of category II and I that require the preservation of normal living conditions.	75
This does not apply to airports with fewer than 10 takeoffs and landings per day and to airports located in the surrounding areas of remote islands. Noise Measurement Method As a principle, measurements should be taken continuously for 7 days, recording peak noise levels that are more than 10 dB above the background noise, and calculating the daily WECPNL using the following formula, then power averaging all these values. Select a location recognized as representative of aircraft noise and conduct the activity outdoors. Select a period recognized as representative of aircraft noise, considering the flight conditions of the aircraft and meteorological conditions such as wind direction. Use the A characteristic of the sound level meter, slow.

On June 29, 2007, a recommendation was received from the Central Environmental Council regarding aircraft noise, leading to a partial revision of the environmental standards concerning aircraft noise, which was officially announced on December 17, 2007.

Table 13-5 "Aircraft Noise" (Revised in 2007)

Types of Regions	Reference value (L_den) below dB
An area exclusively used for residential purposes.	57
Areas outside of category II and I that require the preservation of normal living conditions.	62
This also applies to airports with an average of 10 takeoffs and landings per day or fewer. Noise Measurement Method The equivalent noise level for a day was evaluated by weighting evening and nighttime noise. For the evaluation, the daily L_den was calculated using equation (1), and the power average for all measurement days L_den was calculated using equation (2). However, i, j, and k refer to the i th, j th, and k th observation samples in each time zone, and L_{AE, di} refers to the i th L_AE during the time zone from 7 AM to 7 PM, L_{AE, ej} refers to the j th L_AE during the time zone from 7 PM to 10 PM, and L_{AE, nk} refers to the k th L_AE during the time zones from 12 AM to 7 AM and from 10 PM to 12 AM. Also, T₀ refers to the normalized time (1 second), and T refers to the observation day's time (86400 seconds). N refers to the number of measurement days, and L_{den, i} refers to the i th measurement day of the L_den on the measurement day. (Reference) Internationally, L_den is adopted in EU directives, and many countries such as France and Denmark have also adopted it. Additionally, similar indicators based on equivalent noise levels are adopted by the United States, Austria, and others. Select a location recognized as representative of aircraft noise and conduct the activity outdoors. Select a period recognized as representative of aircraft noise, considering the flight conditions of the aircraft and meteorological conditions such as wind direction. Use the A characteristic of the sound level meter, slow.

Types of Regions

Reference value (L_den)
below dB

An area exclusively used for residential purposes.

Areas outside of category II and I that require the preservation of normal living conditions.

This also applies to airports with an average of 10 takeoffs and landings per day or fewer.
Noise Measurement Method
- The equivalent noise level for a day was evaluated by weighting evening and nighttime noise. For the evaluation, the daily L_den was calculated using equation (1), and the power average for all measurement days L_den was calculated using equation (2).

However, i, j, and k refer to the i th, j th, and k th observation samples in each time zone, and L_{AE, di} refers to the i th L_AE during the time zone from 7 AM to 7 PM, L_{AE, ej} refers to the j th L_AE during the time zone from 7 PM to 10 PM, and L_{AE, nk} refers to the k th L_AE during the time zones from 12 AM to 7 AM and from 10 PM to 12 AM. Also, T₀ refers to the normalized time (1 second), and T refers to the observation day's time (86400 seconds).

N refers to the number of measurement days, and L_{den, i} refers to the i th measurement day of the L_den on the measurement day.

(Reference)
Internationally, L_den is adopted in EU directives, and many countries such as France and Denmark have also adopted it. Additionally, similar indicators based on equivalent noise levels are adopted by the United States, Austria, and others.

Select a location recognized as representative of aircraft noise and conduct the activity outdoors.
Select a period recognized as representative of aircraft noise, considering the flight conditions of the aircraft and meteorological conditions such as wind direction.
Use the A characteristic of the sound level meter, slow.

Table 13-6 "Shinkansen Railway Noise"

Types of Regions	Reference value Below dB
Area primarily used for residential purposes	70
Areas other than those designated for commercial and industrial use that are necessary to maintain normal living conditions.	75
Applicable from 6 AM to 12 PM. The regions to which various types apply are designated by the prefectural governors. Noise Measurement Method For a total of 20 trains passing in sequence, including both ascending and descending trains, the peak levels for each passing train are read, and the upper half of these levels is averaged using a power mean. Noise measurement method. In addition to locations recognized as representative of Shinkansen railway noise, select locations where Shinkansen railway noise is a problem, and measure outdoors at a height of 1.2 meters above ground level. Avoid periods with special weather conditions and times when train speeds are recognized to be lower than usual. Use the A characteristic of the sound level meter, slow.