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1 Subject content and scope of application 1 This specification specifies the technical specifications for sampling toxic substances in workshop air. This specification applies to the measurement and sampling of toxic substances in the air at work sites. This specification does not apply to measurement and sampling when dealing with acute poisoning accidents. 2 Terminology 2.1 Workplace: A place where workers frequently operate or regularly manage and observe during the production process. 2.2 Sampling points: According to the requirements of the measurement, the location for collecting air samples is selected at the work site. 2.3 Collector: Equipment used to collect toxic substances in the air, such as solid adsorbent tubes, various types of absorption tubes, filter materials, and sampling clips. 2.4 Sampling speed: When collecting air samples, the volume of air passing through the collector per minute is expressed in L/min. 2.5 Sampling volume under standard conditions: Converted to the sampling volume at an air temperature of 0°C and an atmospheric pressure of 101.3kPa, expressed in L. Its conversion formula is: in the formula: V0 - converted to sampling volume under standard conditions, L ； t——The temperature at the sampling location,℃ ； P——Atmospheric pressure at the sampling location, kPa ； Vt——Sampling volume at t°C and P, L. 2.6 Sampling duration: Refers to the time required from the beginning to the end of sampling, expressed in min. 2.7 Concentration: The number of milligrams of toxic substances contained in 1 cubic meter of air is expressed in mg/m3. 3 On-site investigation In order to correctly select sampling points, sampling methods and analysis methods, it is necessary to conduct an investigation at the production site before sampling. 3.1 Investigate the raw materials and auxiliary materials used in production, including their names, physical and chemical properties, usage quantities, etc. 3.2 Investigate the production process and understand the names of intermediates, by-products and finished products, as well as possible waste and emissions. 3.3 Investigate the production process and understand the workers’ production operation methods, the places and times they often stay, working postures and labor * Used to wait. 3.4 Understand the existence of toxic substances in the air at the workplace, including the types of toxic substances, their state of existence in the air, estimated concentrations, and the rules or trends of generation, distribution and dissipation, etc. Toxic substances exist in the air as gases and vapors ； Either as aerosol or as vapor and aerosol coexist. 3.5 Investigate health protection measures and facilities as well as personal protection conditions, etc. 4 Selection of sampling points 4.1 Principles of point selection 4.1.1 Sampling points should be located at representative workers’ working locations, and care should be taken to prevent the substance to be measured from directly splashing into the collector. 4.1.2 The selected sampling points must include working places with the highest concentration of toxic substances in the air and where workers have been exposed for the longest time. 4.1.3 The height of the collector set at the sampling point should be within the breathing zone of the worker when working. 5. Evaluation of the effectiveness of anti-virus measures. When evaluating the effectiveness of anti-virus measures, sampling points should be set up according to the situation of the measures. Generally, they should be set up at the workplace to observe the changes in the concentration of toxic substances in the respiratory zones of workers before and after the implementation of the measures. 6 Sampling duration 6.1 The sampling duration should meet the requirements of the determination method and can be determined based on the estimated concentration of the toxic substances to be measured in the air, the sampling speed and the linear range of the determination method. 6.2 The general sampling time is 15 minutes, and the measured result is the average concentration within 15 minutes. 6.3 When the production operation time is less than 5 minutes, it is advisable to take several consecutive samples in the same sampler until the total is 15 minutes. 6.4 When measuring with a monitoring instrument, syringe or trachea test tube, samples can be taken every 3 minutes, measured 5 times within 15 minutes, and the average value can be calculated. 7 Sampling Instruments 7.1 To collect gaseous and vapor toxic substances, use absorption tubes (large bubble absorption tubes, small bubble absorption tubes and porous glass plate absorption tubes), solid adsorbent tubes (activated carbon tubes, silica gel tubes and porous microsphere tubes, etc.), syringes or plastic bags, etc. 7.2 When collecting aerosol toxic substances, use filter materials (microporous filter membranes, perchlorethylene filter membranes, etc.) and their sampling clips or impact absorption tubes. 7.3 When vapor and aerosol toxic substances coexist, use impregnated filter material or filter material plus solid adsorbent to collect. 7.4 The sampling instruments used must fully comply with the instrument specifications. ； Inspection and verification must be carried out before sampling. * * Flow meters used for sampling, such as rotor flow meters, must be calibrated before sampling. The calibration must be carried out with a collector to overcome the impact of the collector's resistance on the flow rate. 7.6 For sampling power, various types of air pumps, gas samplers, dust samplers, etc. can be selected according to needs. 8 Sampling steps 8.1 On-site investigation, select sampling points and determine sampling methods. 8.2 Set up the sampling rack at the sampling point so that the height of the collector is fixed to the breathing belt of the worker during operation. Number the collectors consistent with the sampling records. 8.3 Connect the sampling device in the order of collector - flow meter - sampling power. Avoid connecting any devices (rubber hoses, etc.) in front of the collector. 8.4 Start sampling, quickly adjust the sampling speed to the required value, and pay special attention to maintaining this value during the sampling process. Also record the sampling start time. 8.5 Once the required sampling end time is reached, stop sampling immediately and record the sampling end time. Also record the temperature and atmospheric pressure at the time of sampling. Remove the collector, properly store the sample to prevent sample contamination, loss and deterioration, and send the sample to the laboratory for analysis in a timely manner according to the storage time. 8.6 Each sampling point shall be sampled 3 times in a working shift (8 hours), which may be carried out 1 hour after the start of work, and shall be sampled at least once every 1 hour thereafter. It is advisable to take parallel samples each time. 8.7 At the same time as sampling, blank samples should be brought to the sampling point. Except that air samples are not collected, the rest of the operations are the same as for samples. The number of blank samples should be one-tenth of the total number of samples, at least 3. 9 Sampling records Sampling records should be checked and signed by someone. Someone else should check and sign when collecting samples. The record card is as follows: Appendix A Selection of Toxic Substance Sampling Points and Calculation of Sampling and Measurement Results (Reference) A1 Toxic Substance Sampling Points A1.1 When selecting sampling points, we should first consider the key industries where toxic substances are distributed with serious hazards, a wide range of people exposed, and many occupational cases. A1.2 Specific selection of sampling points A1.2.1 In the same workshop, the same toxic substance, the same type of work, the same type of equipment or the same operation, at least one sampling point should be set up. A1.2.2 Separate sampling points must be set up in the same workshop, the same toxic substances, different types of work, different equipment, and different processes. A1.2.3 Separate sampling points must be set up for different toxic substances in the same workshop. If two toxic substances exist in one sampling point, it will be regarded as two sampling points, and so on. A2 Calculation of sampling measurement results For samples taken at each sampling point at different times, the measurement results are generally taken as the arithmetic mean. __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Additional notes: This specification was proposed by the Health Supervision Department of the Ministry of Health. This specification was drafted by the Shanghai Health and Epidemic Prevention Station and the Institute of Labor Hygiene and Occupational Diseases of the Chinese Academy of Preventive Medicine. The main drafter of this specification: Yan Huaizeng, Hang Shiping This standard is interpreted by the Institute of Labor Hygiene and Occupational Diseases, Chinese Academy of Preventive Medicine Sciences, the technical focal point entrusted by the Ministry of Health.