Published in the Textile Magazine, January 2008


Abstract:


Textile industry is the second largest industry in the world next to agriculture. In India, the textile industry contributes substantially to the foreign exchange earned by the country. The textile industry is providing employment to numerous people in the country. The emphasis on awareness about the environmental concern such as air, water and noise pollution during the processing from fibre to fabric is essential in the present circumstances. There were 1818 mills (non-SSI) in the country as on January 31, 2007 with a capacity of 35.37 million spindles, 4, 48,000 rotors and 69,000 looms. Information regarding cotton dust exposure impacts on workers and its control strategies is missing among textile employers, management and employees. The main aim of this paper is to provide an overview of this issue such as causes, consequences, health hazards arising due to cotton dust and air quality standards available are discussed to facilitate textile mill employers and management to establish cotton dust control strategies to save their workers from its harmful health impacts.


Cotton dust:


Cotton dust is defined as dust present in the air during the handling or processing of cotton, which may contain a mixture of many substances including ground up plant matter, fiber, bacteria, fungi, soil, pesticides, non cotton plant matter and other contaminants which may have accumulated with the cotton during the growing, harvesting and subsequent processing or storage periods.


Any dust present during the handling and processing of cotton through the weaving or knitting of fabrics, and dust present in other operations or manufacturing processes using raw or waste cotton fibers and cotton fiber byproducts from textile mills are considered cotton dust within this definition.


Classification of Cotton Dust:

Table: 1

Type

Size of the particle (μm)

Trash

Above 500

Dust

50-500

Micro dust

15-50

Breathable dust

Below 15


The Micro-dust comprises 50-80% fibre fragments, leaf and husk fragments, 10-25 % sand and earth and 10-25 % water-soluble materials. The high proportion of fibre fragments indicates that a large part of the micro-dust arises in the course of processing. Nearly about 40 % of the micro dust is free between the fibres and flocks, 20-30 % is loosely bound, and the remaining 20-30 % bound to the fibres.


Types of Dust:


1.       Inhalable Dust: It is a term used to describe dust that is hazardous when deposited anywhere in the respiratory tree including the mouth and nose.


Fig.1 Human Respiratory system


2.       Thoracic Dust: It is defined as those materials that are hazardous when deposited anywhere within the lung airways and the gas exchange region.


3.       Respirable Dust: Respirable dust is defined as that fraction of the dust reaching alveolar region of the lungs.


 

Generation of the Cotton Dust during Manufacturing:


  • Ginning factories discharge large amounts of cotton dusts. Cotton ginning and pressing have been identified as traditional industries under the unorganized sector which functions on a seasonal basis.
  • Major problem of cotton dust exists in the blow room and carding section of spinning mill whereas exposure level in other areas is comparatively not much.
  • Poor Relative Humidity follow-up in the department.
  • Blow-down, or blow-off, is the cleaning of equipment and surfaces with compressed air.
  • Cleaning of clothing or floors with compressed air.
  • Improper handling of waste during transportation.
  • Insufficient ventilation system.
  • Improper suction system in the key areas such as blow room and carding and wherever there is a chance of dust generation.
  • When materials such as laps, sliver cans and roving bobbins are delayed in process or stored for an extended period in an area where there is a likelihood of significant dust or lint accumulation. Poor follow-up in covering the material leads to dust formation.
  • Usage of spring loaded cans and carts as waste receptacles creating dust dispersion during compression of the spring loaded bottoms.
  • Poor working procedures and cleaning methods.


Health Hazards Associated with Cotton Dust Exposure:


Workers exposed to cotton dust laden environment generally become patients of byssinosis.


Byssinosis:


It is a breathing disorder that occurs in some individuals with exposure to raw cotton dust. Characteristically, workers exhibit shortness of breath and/or the feeling of chest tightness when returning to work after being in the mill for a day or more. There may be increased cough and phlegm production.


Change in the levels of ESR, LDH3 and Histamine may be used as indicators to assess pulmonary dysfunction in the workers those are exposed to cotton dust. It was suggested that the low hemoglobin and poor immunity against diseases may also predispose the out come pulmonary dysfunction at an earlier stage. Cotton dust extract induces the release of histamine from samples of human lung tissue in vitro. Therefore it is believed that histamine release is responsible for the major symptoms of byssinosis, viz, "chest tightness".


Dr. Richard Schilling, a British physician developed a system of grading workers based on their breathing complaints on the first workday of the week. Schillings classification grades byssinosis according to how far it has progressed. Schillings classifications are as follows.


  • Grade 0 = No complaints of breathing problems.


  • Grade 1/2 = Chest tightness and/or shortness of breath sometimes on the first day of the workweek.


  • Grade 1 = Chest tightness and/or shortness of breath always on the first day of the workweek.


  • Grade 2 = Chest tightness and/or shortness of breath on the first workday and on other days of the workweek.


  • Grade 3 = Chest tightness and/or shortness of breath on the first workday and other days as well as impairment of lung function.


It is believed that the degree or severity of response for individuals with symptoms of byssinosis is related to the dust level in the workplace. The beginning steps in yarn preparation generally produce more dust. Therefore, the closer to the beginning of the process, the higher will be the dust level and the more likely the pulmonary reaction or response for some workers.


 

Permissible Exposure Limits for Cotton Dust for Different Work Areas:


Table: 2


Department

PEL (Micrograms per cubic meter)

Opening

200

Picking

200

Carding

200

Combing

200

Roving

200

Spinning

200

Winding

200

Warping

200

Slashing

750

Weaving and Knitting

750

Waste house

750


Medical Monitoring:


Medical examinations are to be provided to prospective employees prior to their initial assignment. As a minimum, the examinations should include:


  • A medical history to identify any existing health problems or diseases that may affect breathing.
  • A standardized respiratory questionnaire inquiring about such concerns as cough, chest tightness and smoking history.
  • A pulmonary function (breathing) test including the forced vital capacity (FVC), the amount of air one can force out after taking a deep breath and forced expiratory volume in 1 second (FEV1), the amount of air forced out during the first second of expiration.


Environmental Exposure monitoring:


  • Sampling of the workplace must be done at least every six months to determine the amount of cotton dust in the environment.
  • Measurements must be representative of all employees in the workplace.
  • Sampling will be done in all work areas and on each shift.
  • Sampling is done for a period equal to at least three-quarters of the shift.
  • While sampling is being done, other information is collected that may pertain to the generation of cotton dust. The percent of cotton fiber in the mix; the grade of the cotton and where it was grown; types of yarn being run; and the number and types of machines operating in each area may all affect the amount of cotton dust in the workplace.


Vertical Elutriator:


It is used to monitor employee exposure to cotton dust in the workplace. Airs is drawn into the vertical elutriator at a specified speed, and particles of 15 microns or smaller are collected on a filter. The particles collected are measured to determine the amount of respirable dust (dust that can get into 4 the lungs) there is in the work area. It is important to realize that other dusts, such as starch or oil mist are also collected

on the filter and may contribute to the cotton dust levels.


Fig 2 Vertical Elutriator


 

Dust Control Measures:


         Monitoring of cotton dust concentration in the occupational environment

         Provide medical surveillance to the cotton dust exposed workers

         Establishing safe working practices to reduce the exposure level

         Training and education of workers

         Engineering controls to reduce the emission

         Use of dust masks 



Preventive measures to be followed during manufacturing process:


General practices:


  • Usage of compressed air for cleaning purposes should be prohibited when other means of cleaning are possible. Where blow-down cleaning is done (meaning general cleaning of the entire room, including the walls and ceilings ventilation ducts), employees performing the cleaning must wear respirators.
  • All other employees not involved with the blow-down cleaning must leave the area.
  • Cleaning of clothing or floors with compressed air is prohibited.
  • Floor sweeping will be done by vacuum or other methods designed to minimize the breathing of dust.
  • Waste will be handled by mechanical means. Manual handling should be limited as much as possible.
  • Ventilation systems should be inspected regularly.


Work practices during Material handling and cleaning:

  • Cotton, Cotton waste and materials containing cotton dust should be stacked or handled properly in such a way that will reduce dust level.
  • Brooms should be used properly so that dust will be controlled and vacuum cleaners should be used wherever dust control is difficult.
  • When cleaning machines with brushes or cloths, the individual doing the cleaning should stroke the waste from top to bottom as far from the face as possible. Surfaces should not be beaten or fanned during cleaning.
  • Waste should be placed in the corresponding waste storage container immediately before accumulating in the floor.
  • Waste receptacles or waste transport containers should be placed in the respective places such that disturbance creating by any means would be avoided.
  • Waste receptacles should not be overfilled such that material spills to the floor during storage or transport to the waste godown.
  • Spring-loaded cans and carts should not be used as waste receptacles in order to avoid dust dispersion during compression of the spring-loaded bottoms.
  • When materials such as laps, sliver cans and roving bobbins are delayed in process or stored for an extended period in an area where there is a likelihood of significant dust or lint accumulation, the materials should be covered. The storage area and the covers should be periodically cleaned to prevent lint and dust accumulation.


Conclusion:


As being the largest contributor to the national economical growth, we are giving atmost emphasis to the textile industry especially in terms of developing high speed machineries, versatile machines and high quality products. At the same time we must focus on health conditions of the human involving in the manufacturing process and environmental conditions. Textile management and employer should follow the work procedures to control the cotton dust exposure to workers. The cotton dust which is creating health hazards to the lakhs of labours involving in the textile manufacturing process should be controlled by creating awareness among the workers and by the effective management.


 

References:


1. A Guide for Persons Employed in Cotton Dust Environments by U.S. Department of Labor, Occupational Safety and Health Administration; U.S. Department of Health and Human Services (NIOSH), and NCDOL personnel .(pdf in website)

2. An Article on Air pollution in Central pollution control board India (website)

3. The Technology of Short staple spinning by Klien

4. Biochemical profile of gin women laborers in Tirupur- a study found in website.


About the Author:


R. Senthil Kumar is associated with Department of Textile Technology, Indian Institute of Technology, New Delhi.



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