Circular No. 28/2011/TT-BTNMT stipulates the technical procedures for monitoring ambient air quality and noise.

CIRCULAR

TECHNICAL PROCEDURE FOR ENVIRONMENTAL MONITORING OF SURROUNDING AIR AND NOISE

Pursuant to Decree No. 25/2008/NĐ-CP dated March 4, 2008 of the Government on the functions, tasks, powers, and organizational structure of the Ministry of Natural Resources and Environment, amended and supplemented by Decree No. 19/2010/NĐ-CP dated March 8, 2010 and Decree No. 89/2010/NĐ-CP dated August 16, 2010;

Pursuant to the Government Decree No. 102/2008/NĐ-CP, September 15, 2008, on the collection, management, exploitation, and utilization of data on natural resources and the environment;

Pursuant to Decision No. 16/2007/QĐ-TTg dated January 29, 2007 of the Prime Minister approving the overall planning of the national environmental monitoring network until 2020;

Considering the proposal of the General Director of the Environmental Administration, the Director of the Science and Technology Department, and the Director of the Legal Affairs Department,

c) Enterprises may be granted permission for no more than one block out of the total three dual-frequency blocks (FDD) B

PART I
GENERAL PROVISIONS

Article 1. Scope of Regulation

This Circular stipulates the technical procedures for environmental monitoring of surrounding air and noise, including: determining the objectives of monitoring, designing the monitoring program, and implementing the monitoring program.

Article 2. Applicability

1. This Circular applies to the following subjects:

a) State management agencies on the environment at central and local levels; stations and centers for environmental monitoring within the national environmental monitoring network and the local environmental monitoring network;

b) Organizations with functions and tasks related to environmental monitoring activities and environmental monitoring service activities to submit reports and data to state management agencies on the environment at central and local levels;

This Circular does not apply to environmental monitoring of surrounding air and noise using automatic and continuous devices.

Article 3. Explanation of Terms

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Surrounding air is outdoor air that humans, plants, animals, or materials may come into contact with.

2. Dust: is a fine dispersion system where the dispersing medium is the gas phase, while the dispersed phase consists of solid particles larger than molecular size but smaller than 100 μm.

Article 4. Principles for applying standards and referenced methods

The application of standards and referenced methods must comply with the monitoring and analysis standards and methods prescribed in Chapter II of this Circular.

In cases where the monitoring and analysis standards and methods prescribed in Chapter II of this Circular are revised, supplemented, or replaced, the new standards and methods shall be applied.

Chapter II
TECHNICAL PROCEDURE FOR ENVIRONMENTAL MONITORING OF SURROUNDING AIR

Article 5. Monitoring Objectives

Basic objectives in monitoring surrounding air are:

1. Determining the degree of air pollution affecting public health according to current permissible standards;

2. Determining the impact of individual or groups of emission sources on the quality of local ambient air;

3. Providing information to assist in planning pollution control and industrial development planning;

4. Evaluating changes in ambient air quality over time and space;

5. Warning about air pollution;

6. Meeting the requirements of central and local environmental management work.

Article 6. Design of Monitoring Program

After design, the monitoring program must be approved or accepted in writing by the competent authority or the agency managing the monitoring program. The specific design of the surrounding air environmental monitoring program is as follows:

1. Type of Monitoring

Based on the monitoring objectives, when designing the monitoring program, it is necessary to determine whether the type of monitoring is background monitoring or impact monitoring.

2. Monitoring Location and Position

a) Determining the location and position of surrounding air monitoring is based on the objectives of the monitoring program;

b) Before selecting the location and position for monitoring, it is necessary to investigate and survey the sources of pollution causing air pollution in the area to be monitored. After conducting field surveys, the positions of the monitoring points are marked on maps or diagrams;

c) When determining the positions of surrounding air monitoring points, attention should be paid to:

- Weather conditions: wind direction, wind speed, solar radiation, humidity, air temperature;

- Topography: the topography of the monitoring site must be convenient, well-ventilated, and representative of the area of interest. In areas with complex topography, the monitoring positions are mainly determined based on local dispersion conditions.

3. Monitoring Parameters

a) First, information and field surveys must be conducted to understand information about the monitoring location (residential areas, production zones...), types of production, emission locations, and sources from which to accurately select characteristic and representative parameters for the monitoring location;

b) Basic parameters selected to assess the quality of surrounding air are:

- Mandatory parameters measured on-site: wind direction, wind speed, temperature, relative humidity, pressure, solar radiation;

- Other parameters: sulfur dioxide (SO₂), nitrogen dioxide (NO₂), nitric oxide (NO_x), carbon monoxide (CO), ozone (O₃), total suspended particulate matter (TSP), particulate matter less than or equal to 10 μm (PM₁₀), lead (Pb);

c) Depending on the objectives and requirements of the monitoring program, other parameters can also be monitored according to QCVN 06: 2009/BTNMT.

4. Monitoring Time and Frequency

a) Monitoring time depends on factors such as:

- Monitoring objectives;

- Monitoring parameters;

- Operation status of emission sources inside and adjacent to the monitoring area;

- Meteorological factors;

- Monitoring equipment;

- Whether the monitoring method is active or passive;

- Data processing methods;

- Sensitivity of analytical methods.

b) Monitoring frequency

- Background monitoring frequency: at least once per month;

- Impact monitoring frequency: at least six times per year.

c) Considerations when determining monitoring frequency:

When there are cyclical changes in air quality, the interval between consecutive sampling times must be short enough to detect these changes;

5. Monitoring Plan

The monitoring plan is based on the monitoring program and includes the following contents:

a) List of personnel responsible for monitoring and assignment of tasks to each participating staff member;

b) List of organizations and individuals participating and cooperating in environmental monitoring (if any);

c) List of field monitoring equipment, tools, chemicals, and laboratory analysis equipment;

d) Safety equipment and measures to ensure safe labor during environmental monitoring activities;

d) Types of samples to be collected, sample volume, and sample storage time;

e) Laboratory analysis methods.

g) Budget for implementing environmental monitoring;

h) Plan to ensure quality and quality control in environmental monitoring.

Article 7. Implementation of Monitoring

The organization of the monitoring program includes the following tasks:

1. Preparation work

Prior to conducting monitoring, preparatory work must be carried out as follows:

a) Preparing documents, maps, diagrams, and general information about the area where samples will be taken;

b) Monitoring weather conditions and weather trends;

c) Preparing necessary tools and equipment; inspecting, cleaning, and calibrating sampling, measuring, and testing devices before going to the field;

d) Preparing chemicals, materials, and tools for sample collection and preservation;

đ) Preparing sample labels, monitoring and analysis forms, and logs as prescribed;

e) Preparing means of transportation and support for sample collection activities;

g) Preparing safety equipment and ensuring workplace safety;

h) Preparing funds and personnel for monitoring;

i) Preparing accommodation facilities for staff working for extended periods;

k) Preparing other relevant documents and forms;

2. Sampling, Measurement, and Analysis at the Site

a) At the sampling location, meteorological parameters (temperature, humidity, atmospheric pressure, wind speed and direction) shall be measured on-site;

b) Based on the quality objectives of the data, the methods of measurement, analysis, and air sampling must comply with one of the methods specified in Table 1 below:

Table 1. Methods of Measurement, Analysis, and Air Sampling at the Site

b) When there are no national standards for on-site air sampling, measurement, and analysis as specified in Table 1 of this Circular, international standards listed in Table 1 or other international standards with equivalent or higher accuracy shall be applied;

c) Quality assurance and control measures at the site shall be implemented according to guidelines issued by the Ministry of Natural Resources and Environment regarding quality assurance and control in environmental monitoring.

3. Sample Storage and Transportation

a) The method of storing samples must be appropriate for the monitored parameters and laboratory analytical techniques. Samples collected must be analyzed immediately; if not, they must be stored cold at 5°C for no more than 24 hours;^°b) For samples collected using absorption methods, the absorbed solution must be transferred to a securely sealed glass bottle, placed in a rack, and carefully packed in a cold storage box;

c) For CO samples collected using volume substitution methods, the sample containers must be neatly arranged without stacking or being crushed by other objects to prevent breakage and minimize leakage;

d) For dust samples, the samples must be placed in double bags, securely sealed, and stored in a closed container under normal conditions;

4. Laboratory Analysis

a) Based on the quality objectives of the data and laboratory conditions, the analysis of parameters must follow one of the methods specified in Table 2 below:

Table 2. Methods of Analyzing Parameters in the Laboratory

• TCVN 5978:1995 (ISO 4221:1980)

c) Quality assurance and control measures in the laboratory shall be implemented according to guidelines issued by the Ministry of Natural Resources and Environment regarding quality assurance and control in environmental monitoring.

5. Data Processing and Reporting

a) Data Processing

- Data verification: verifying the overall rationality of the monitoring and analysis data based on the sample documentation (field sampling log, sample transfer records, on-site measurement results, laboratory analysis results, etc.), QC sample data (blank samples, replicate samples, standard samples, etc.);

- Statistical processing: based on the number of samples and the report content, different statistical methods and software may be used but must include minimum descriptive statistics (minimum value, maximum value, average value, number of values exceeding standards, etc.);

- Commenting on data: comments on the data must be based on processed, verified monitoring and analysis results and related technical standards and specifications.

b) Reporting Results

After completing the monitoring program, the monitoring results report must be prepared and submitted to the competent state authority as prescribed.

TECHNICAL PROCEDURE FOR NOISE MONITORING

Chapter III
TECHNICAL PROCEDURE FOR NOISE MONITORING

Article 8. Objectives of Monitoring

The basic objectives in noise monitoring are:

1. To determine the level of noise affecting community health according to current permissible standards;

2. To identify the impact of individual noise sources or groups of noise sources;

3. To provide information for planning noise control;

4. To assess the temporal and spatial evolution of noise pollution;

5. To warn about noise pollution;

6. Meeting the requirements of central and local environmental management work.

Article 9. Design and Implementation of Noise Monitoring Programs

1. Locations for Noise Monitoring

a) National Technical Regulation QCVN 26: 2010/BTNMT sets national technical standards for noise, specifying maximum noise levels in areas where people live, work, and operate; the noise in these standards is generated by human activities regardless of the type of noise source or location of noise generation.

b) Areas that must be measured for noise include:

- Special quiet zones: hospitals, libraries, nursing homes, kindergartens, schools;

- Residential areas, hotels, houses, administrative offices;

- Commercial and service areas;

- Production areas located within residential areas.

c) The selection of noise monitoring points should follow the national standard TCVN 5964:1995. In particular, the following points should be noted:

- The selected location must be representative of the area to be monitored (must have defined coordinates);

- Avoid obstacles causing sound reflection;

- Avoid artificial interference sources: music, metal impacts, children playing...;

- Choose a measurement position that ensures the most stable sound transmission with constant wind direction from the source to the measurement point.

d) For industrial production facilities, noise monitoring must be conducted at positions specified in the national standard TCVN 3985:1999.

2. Monitoring Parameters

Parameters in noise monitoring include:

a) L_Aeq equivalent sound level;

b) L_Amax maximum equivalent sound level;

c) L_AN,T percentile level;

d) Frequency analysis of noise in octave bands (in industrial zones);

đ) Traffic flow intensity (for traffic noise).

3. Time and Frequency of Monitoring

a) Frequency of Monitoring

The frequency of noise monitoring is determined based on the requirements of the monitoring program management agency, budget, and the purpose of the monitoring program but must be at least four times per year.

b) Duration of Monitoring

- For noise in specified areas and traffic noise: continuous measurement for 12, 18, or 24 hours depending on the requirement;

- For noise in production facilities, measurements must be taken during working hours;

- Since sound levels are affected by weather conditions, when selecting the time for noise monitoring, the following points should be noted:

+ Measurement periods should be chosen such that the average sound level is determined within a range of weather conditions occurring at the measurement locations;

+ Measurement periods should be chosen to ensure that measurements are conducted under truly characteristic weather conditions.

4. Monitoring Equipment

a) Equipment used follows the national standard TCVN 5964:1995;

b) The equipment used includes integrating sound level meters equipped with frequency analyzers. In cases where there are no integrating sound level meters, measurements can be made using contact sound level meters, with intervals recorded and statistical distribution methods used to calculate L_Aeq,T :

Of which

- T = ∑t_i: total sampling time required;

- t_i : duration of the sound level LA_i; (corresponding to the i-th measurement);

-_Ai: sound level according to characteristic A existing during time t_i;

- n: number of sound level measurements.

c) To ensure the quality of monitoring, sound level meters must be calibrated using a sound source standard at levels of 94 and 104 dBA before each monitoring session and periodically calibrated at authorized calibration agencies.

5. Monitoring Methods

The method and duration of monitoring are selected according to the national standards TCVN 5964:1995 and TCVN 5965:1995.

a) Measurements

When conducting outdoor measurements, sound reflections must be minimized. Measurements must be carried out at least 3.5 meters away from reflective structures, excluding the ground. If no other provisions apply, the measurement height should be between 1.2 and 1.5 meters above ground level.

b) Outdoor Measurements Near High-Rise Buildings

These measurements are conducted at positions where noise concerning high-rise buildings needs attention. If no other instructions apply, the best measurement positions are 1 to 2 meters away from the building and 1.2 to 1.5 meters above ground level.

c) Traffic Noise Measurements

- Measurement height should be between 1.2 and 1.5 meters above ground level;

- Sound reflections must be minimized;

- Interfering noise sources must be avoided.

d) Indoor Measurements

- These measurements are conducted inside fences where noise is of concern. If no other instructions apply, measurement positions should be at least 1 meter away from walls or other reflective surfaces, 1.2 to 1.5 meters above the floor, and 1.5 meters from windows; 7.5 meters from the noise source;

- When measuring noise caused by industrial machines, noise must be measured according to frequency in the 1:1 octave band (according to the national standard TCVN 3985:1999).

đ) Points to Note

- Continuous measurement duration for each measurement is 10 minutes, with three measurements conducted within one hour, followed by averaging the results of the three measurements. The result obtained is considered the average value of the measurement hour;

- For traffic noise caused by vehicle flow, in addition to measuring noise, the vehicle flow intensity (vehicles/hour) must be determined manually or automatically. Vehicle types in the flow must be classified, including:

+ Extra-large vehicles (containers and over 10 wheels);

+ Trucks and buses;

+ Cars (under 12 seats);

+ Motorcycles and scooters.

- When measuring noise levels in octave bands, the procedure is similar, but note that after setting the time, the frequency measurement mode in the 1:1 octave band must be set.

6. Data Processing and Reporting

- Data verification: verifying the overall rationality of the monitoring and analysis data based on the sample documentation (field sampling log, sample transfer records, on-site measurement results, laboratory analysis results, etc.), QC sample data (blank samples, replicate samples, standard samples, etc.);

- Data verification: comprehensive review of the rationality of the noise monitoring data. Verification is based on monitoring records (minutes, logs, field measurement results, etc.).

- Statistical processing: based on the quantity of measurement results and the content of the report, statistical processing may use various methods and software but must include at least basic descriptive statistics (minimum value, maximum value, average value, number of values exceeding standards...);

- Commenting on data: commenting on data must be carried out based on processed monitoring results, verification, and relevant technical standards and regulations;

After completing the monitoring program, the monitoring results report must be prepared and submitted to the competent state authority as prescribed.

After completing the monitoring program, a noise monitoring result report must be prepared and submitted to the competent state agency as prescribed;

Chapter IV
IMPLEMENTATION

Article 10. Implementation Organization

1. The General Department of Environment shall be responsible for guiding, inspecting, and supervising the implementation of this Circular;

2. The Minister, Heads of ministerial-level agencies, Heads of government-affiliated agencies, Chairpersons of People's Committees at all levels, and organizations and individuals related to this matter shall be responsible for implementing this Circular;

Article 11. Effective Date

1. This Circular takes effect from September 15, 2011;

2. During the implementation of this Circular, if there are difficulties or obstacles, agencies, organizations, and individuals are requested to reflect them to the Ministry of Natural Resources and Environment (through the General Department of Environment) for timely consideration and resolution./.