Microclimate- permissible value of microclimate in the workplace
For the purpose of this Regulation, terms herein shall be construed as follows:
– Microclimate in the workplace is the atmospheric conditions in the workplace, including the combined effects of temperature, humidity, air velocity and surface temperature of utensils and instruments surrounding workers.
– Temperature is a parameter indicating the heat of a physical individual, denoted 0C.
– Humidity:
+ Absolute humidity (Ha) is the water content of air at certain time and a given temperature expressed in gram per cubic meter.
+ Maximum humidity (Hm) or saturated humidity is the saturated water content of air at certain time and a given temperature expressed in gram per cubic meter.
+ Relative humidity (Hr) is the ratio of the absolute humidity to maximum humidity, expressed in percentage.
– Air velocity is the speed of natural and mechanical air movement in a confined space in the workplace, expressed in m/s.
– Radiant heat is the exchange of thermal energy without the direct contact between particles.
– Light work is a job which involves standing, walking, and sitting and in which a worker is required to frequently use his/her hands most of the time. Light work burns 120 – 150 kcal per hour.
– Medium work is a job which involves standing, walking, moving, processing components weighing less than 1 kg while standing or sitting, and lifting or carrying objects of no more than 10 kg. Medium work burns 151-250 kcal per hour.
– Heavy work is a job and work activity in which a worker is frequently required to carry out while standing or walking, to process and to move objects weighing more than 10 kg. Heavy work burns more than 250 kcal per hour.
– Wet bulb globe temperature (WBGT) is an experimental index of heat stress of an individual exposed.
WBGT index is determined based on two derivative parameters, namely the natural wet-bulb temperature (tnw) and black globe thermometer temperature (tg); in some cases, WBGT is determined based on only dry-bulb temperature (ta).The WBGT index is calculated using the following formula:
– Indoor and outdoor conditions with no solar load:
T°WBGT= 0.7 tnw + 0.3 tg
– Outdoor condition with solar load:
T°WBGT = 0.7 tnw + 0.2 tg + 0.1 ta
Requirements for microclimatic conditions in the workplace are classified by kind of work as presented in Table 1.
Where the workplace is hot and has high humidity, the air velocity therein may increase to 2 m/s.
Where the workplace having air conditioners and the ventilation is in good condition to ensure the permissible concentration of CO2, the air velocity therein may be less than 0.1 m/s if workers perform light work, less than 0.2 m/s and less than 0.3 m/s if workers perform medium and heavy work, respectively.
The difference in temperature by altitude shall not exceed 3 0C.
The difference in temperature by horizontal direction in the workplace where workers perform light, medium and heavy work shall not exceed 4°C, 5°C and 6°C, respectively. The difference between outdoor temperature and indoor temperature shall not exceed 5°C.
Requirements for microclimatic conditions in the workplace by WBGT are presented in the table 2.
The workplace where workers contact with microclimate elements shall be periodically inspected once every year in accordance with regulations on the Labor Code and Law on Occupational Safety and Hygiene.
Employers shall provide their employees with sufficient personal protective equipment which is suitable to use in the workplace under the Law on Occupational Safety and Hygiene.
Where any microclimate parameter fails to meet permissible standards, the employer shall take actions for improving the working environment and protecting employees’ health.
This Regulation replaces the Regulation on microclimate in the Occupational Hygiene Regulation enclosed with the Decision No.3733/2002/QD-BYT dated October 10, 2002 by the Ministry of Health.
(Nguồn tin: vnniosh.vn)
