Respirable Dust Measurement and Control in Mines – DGMS Guidelines & 25 MCQs

🧾 DETAILED NOTES

1️⃣ Introduction

Respirable dust is fine airborne particulate matter that can enter the lungs and cause serious diseases such as pneumoconiosis and silicosis. In coal and metalliferous mines, dust is generated during drilling, blasting, loading, and transportation operations. DGMS mandates regular measurement and control of respirable dust levels to protect workers’ health and ensure compliance with statutory limits.

2️⃣ DGMS Safety Concern

Pneumoconiosis is a chronic, irreversible lung disease caused by prolonged inhalation of mineral dust. DGMS accident and health reports indicate several occupational cases due to non-compliance with dust monitoring and control standards. Hence, dust measurement and suppression are a statutory requirement in all underground and opencast mines.

3️⃣ Legal Framework

Reference	Description
The Mines Act, 1952 – Sec. 23	Safety and health of workers.
CMR 2017 – Regulation 123	Dust control and ventilation requirements.
DGMS Technical Circular (Tech.) No. 08/2018	Guidelines for respirable dust monitoring.
DGMS (Occupational Health) Circular No. 01/2010	Prevention of pneumoconiosis and silicosis.
The Mines Rules, 1955 – Rule 29B	Periodic medical examination and dust exposure monitoring.

4️⃣ Objective

To monitor respirable dust levels and maintain them below permissible limits.
To prevent occupational diseases like pneumoconiosis, silicosis, and asbestosis.
To ensure compliance with DGMS and health regulations.
To safeguard miners’ health and ensure sustainable mining practices.

5️⃣ Definition

Respirable Dust: Dust particles ≤ 5 microns in size that can penetrate deep into the lungs and remain suspended in air for long periods.

Pneumoconiosis: A lung disease caused by continuous inhalation of mineral or coal dust leading to fibrosis or scarring of lung tissues.

6️⃣ Measurement of Respirable Dust

🧪 Instruments Used: Gravimetric Dust Sampler (GDS), Personal Dust Sampler (PDS), Real-Time Dust Monitor, High-Volume Sampler (HVS).

🕐 Sampling Procedure:

Select representative locations (e.g., face, haul road, workshop).
Operate sampler at a flow rate of 1.5–2.2 L/min for 8 hours.
Weigh filter paper before and after sampling.
Calculate dust concentration.

7️⃣ Permissible Limits of Respirable Dust

Mine Type	Dust Concentration (mg/m³)	Remarks
Coal Mines	3 mg/m³	Total dust concentration
Metal Mines	2 mg/m³	Silica content > 5%
Quartz Mines	0.1 mg/m³	High risk of silicosis
Asbestos Mines	0.5 fibre/cc	As per DGMS/ILO standards

8️⃣ Control Measures

🌧️ A. Engineering Controls: Water spraying systems on drills, crushers, and conveyors; Wet drilling; Dust extraction systems; Proper mine ventilation and auxiliary fans; Enclosure of dust sources.

🧰 B. Administrative Controls: Rotation of workers to reduce exposure; Regular dust sampling; Maintenance of dust suppression equipment; Signage in high dust areas.

😷 C. Personal Protective Equipment (PPE): Use of approved dust respirators (IS 9473); Training on respirator fitting and use; Periodic replacement of filters.

9️⃣ Medical Surveillance

Periodic medical examinations every 5 years (Rule 29B).
Chest X-rays and spirometry for workers in dust-prone areas.
Maintenance of health cards and exposure records.

⚙️ QUICK ONE-LINERS (Revision Points)

DGMS Circular 08/2018 → Dust monitoring guidelines.
Respirable dust ≤ 5 µm in size.
Pneumoconiosis = chronic lung disease from dust.
Gravimetric dust sampler used for measurement.
Coal mine limit = 3 mg/m³.
Wet drilling reduces dust by 80%.
Rule 29B – medical examination every 5 years.
DGMS Circular 01/2010 → Prevention of silicosis.
Proper ventilation = key to dust control.
PPE must meet IS 9473 standard.

🧩 DESCRIPTIVE MODEL QUESTION & ANSWER

Q. Explain the methods of measurement and control of respirable dust to prevent pneumoconiosis in mines.

Answer:
Respirable dust (≤ 5 µm) is measured using Gravimetric Dust Samplers or Personal Dust Samplers. Samples are collected for 8 hours and analyzed to determine mg/m³ concentration. Permissible Limits: Coal mines (3 mg/m³), Metal mines with silica > 5% (2 mg/m³). Control Measures: (1) Engineering: Wet drilling, water spraying, ventilation, and dust extraction. (2) Administrative: Job rotation and regular sampling. (3) PPE: Use of approved respirators. These measures prevent pneumoconiosis and ensure compliance with DGMS Circular 08/2018 and CMR 2017 Reg. 123.

🧮 25 DGMS-Based MCQs (5 Options Each)

Q1. DGMS Circular on dust monitoring:

Solution: DGMS Technical Circular 08/2018 provides the most recent comprehensive guidelines for respirable dust monitoring.

Q2. Regulation for dust control:

Solution: Regulation 123 of CMR 2017 specifically outlines the precautions required against dust.

Q3. Respirable dust size:

Solution: Respirable dust particles are defined as those small enough (typically 5 microns or less) to penetrate the deep lung tissue.

Q4. Disease caused by inhaling dust:

Solution: Pneumoconiosis is the general term for lung diseases caused by the inhalation of mineral dusts.

Q5. Coal mine respirable dust limit:

Solution: The permissible limit for respirable dust in coal mines is 3 mg/m³ of air.

Q6. Dust sampler used:

Solution: A Gravimetric Dust Sampler is the standard instrument used to measure the mass (weight) of dust in a volume of air.

Q7. Wet drilling used to:

Solution: Wet drilling is a primary engineering control that suppresses dust at the source and also helps cool the drill bit.

Q8. PPE for dust:

Solution: A respirator (dust mask) is the specific PPE designed to protect against inhaling airborne dust.

Q9. DGMS Circular 01/2010 deals with:

Solution: This circular from the (Occupational Health) division specifically addresses the prevention of silicosis in mines.

Q10. Medical exam frequency (PME < 45 years):

Solution: As per Mines Rules 29B, PME is conducted once in every 5 years for workers below 45 years of age.

Q11. Metal mine dust limit (Silica > 5%):

Solution: For metalliferous mines where free silica content is above 5%, the respirable dust limit is stricter, at 2 mg/m³.

Q12. Wet drilling reduces dust by:

Solution: Wet drilling is a highly effective engineering control, often reducing respirable dust generation by over 80-90%.

Q13. High-Volume Sampler used in:

Solution: HVS are large samplers used to monitor ambient (general area) dust levels, primarily in surface mines or near mine boundaries.

Q14. Real-time monitor:

Solution: A DUSTTRAK is a brand of photometer that provides immediate, real-time readings of dust concentration.

Q15. Dust filters weighed:

Solution: In gravimetric sampling, the mass of dust collected is found by subtracting the pre-sampling weight from the post-sampling weight.

Q16. DGMS stands for:

Solution: DGMS is the Directorate General of Mines Safety.

Q17. Personal dust sampler measures:

Solution: PDS is worn by a worker to measure the actual amount of respirable dust they are exposed to during their shift.

Q18. Rule 29B relates to:

Solution: Rule 29B of the Mines Rules, 1955, outlines the requirements for Initial and Periodic Medical Examinations (IME & PME).

Q19. Pneumoconiosis affects:

Solution: Pneumoconiosis is a group of interstitial lung diseases caused by the inhalation of mineral dusts.

Q20. Dust monitoring frequency:

Solution: DGMS circulars typically mandate a minimum frequency of quarterly (every 3 months) dust sampling for monitoring.

Q21. Engineering control example:

Solution: Water spraying is an engineering control that removes dust from the air. Job rotation and PPE are administrative and personal controls, respectively.

Q22. Dust suppression system type:

Solution: Water mist or fogging systems are commonly used at transfer points and crushers to suppress dust.

Q23. Health record maintained under:

Solution: The Mines Rules, 1955 (specifically Rules 29B, 29M, 29P, etc.) detail the requirements for medical examinations and health registers (Forms O & P).

Q24. Respirator standard:

Solution: IS 9473 is the Indian Standard for "Respiratory protective devices - Filtering half masks to protect against particles".

Q25. Goal of dust control:

Solution: The primary health objective of respirable dust control is to prevent irreversible lung diseases like pneumoconiosis.

🔗 INTERNAL LINKS

Related Topic	Read More On...
Occupational Health	Occupational Health Surveillance in Mines
Dust Diseases	Dust Diseases: Silicosis & Pneumoconiosis
DGMS Circulars	DGMS Circular on Dust Suppression
Health Rules	Medical Re-examination by Appellate Board

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