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World at work: Manufacturing “Tatami” mats in China
  1. G-B Xiao1,
  2. K Morinaga2,
  3. R-Y Wang3,
  4. X Zhang4,
  5. Z-H Ma5
  1. 1Ningbo Municipal Agency for Public Health Inspection, Ningbo 315010, P R China
  2. 2Osaka Medical Center, Osaka 537-8511, Japan
  3. 3Health Bureau of Ningbo, Ningbo, 315010, P R China
  4. 4The Academy of Medical Sciences, Zhejiang Province, Hangzhou, 310013, P R China
  5. 5Ningbo Municipal Centre for Disease Control and Prevention, Ningbo 315010, P R China
  1. Correspondence to:
 Associate Professor G-B Xiao
 Ningbo Municipal Agency for Public Health Inspection, 37 Yongfeng RD, Ningbo 315010, China;

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Exposure to dust may cause respiratory problems

Tatami matting produced from rush is used in almost all households in Japan. Now, most matting products are imported from China. Rush cultivation and processing began in the 1980s in China, being introduced from Japan. In 1999, the cultivation area had increased to 5980 hectares, and exports of matting to Japan were 45 000 metres in a local area of China. Chinese researchers have recently found some serious occupational hazards in the industry.


To keep the colour of the mat, the raw rush mat has to be initially smeared with mud (fig 1), and then dried by heat flow before being processed into a mat. A growing number of casual workers are employed in the process, which includes drying, selecting, weaving, and other activities.

Figure 1

Raw rush being immersed in mud, and then dried.


In the late 1990s, it was found that workers were heavily exposed to dust from the mud during the process in the rush matting enterprises in China (figs 2 and 3). The geometric mean (GM) of total dust concentration in the workplace was 20.00 mg/m3, and that of respirable dust was 8.22 mg/m3. The content of free silica in the worksite sedimentation dust was 25.6% on average. Exposure to crystalline silica can result in adverse pulmonary responses such as acute silicosis, accelerated silicosis, chronic silicosis, and conglomerate silicosis. Among 661 workers who underwent chest x ray examination, the prevalence of small opacities of profusion category ⩾1/0 was 2.57%. The NIOSH recommended exposure limit is 50 µg/m3 for up to 10 h/day for a 40 hour working week. The Chinese maximum allowable concentration is 2 mg/m3 for total dust (10–50% SiO2), and 1 mg/m3 for respirable dust (10–50% SiO2). There is evidence that exposures routinely exceed the standards. Although it is well known that smoking contributes to the development of pneumoconiosis, some workers still smoke during the operations (fig 4).

Figure 2

Quality control by selecting and refining the dried mud.

Figure 3

The refined and coloured rush being weaved into mats.

Figure 4

A worker smoking during the rush selection operation.


Many preventive measures have been recommended by the Municipal Agency for Public Health Inspection to help the enterprises to protect workers:

  • Guiding the industry towards providing a healthy and safe workplace; production will not be allowed to continue without meeting the requirements.

  • Conducting technological innovation (mechanical processes) and using industrial engineering to reduce dust levels close to national occupational exposure limits. Otherwise, effective protective masks must been used.

  • Using epidemiological investigations to collect basic data on the prevalence of pneumoconiosis. Enforcing worker health surveillance, especially chest x ray checks.

However, the process of controlling dust pollution and the elimination of pneumoconiosis is likely to be a long term struggle.

Exposure to dust may cause respiratory problems


  • G B Xiao is now attending a PhD programme at Fudan University School of Public Health, Shanghai, 20032, P R China