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National Occupational Health Service Centre Bhilai Steel Plant A Study on Carboxy Haemoglobin Level Among Employees Exposed to CO in Bhilai Steel Plant Dr. A.K.Verma Sr. Manager National OHS Centre Bhilai Steel Plant, Bhilai
Introduction Bhilai Steel Plant • CO is the most significant health hazard in Steel Plant. • There is a large network (62892 mtr.) of mixed gas line throughout the plant. • CO is produced due to carbonization in Coke over battery smelting of iron in BF and maintenance of vehicle in ARS. • Study was conducted on 111 employees (61 exposed & 50 non-exposed) • Work zone CO concentration, exhaled air CO concentration, COHb%, Personal habits were evaluated for study group.
CO - Some Facts Bhilai Steel Plant • CO is a colorless, odorless, non-irritant gas lighter than air but when mixed with other gases density may change. • It is formed by combustion of carbon and organic matter. • CO affinity to human Hb is 210 times more than its affinity to O2. • Small quantities of CO is produced within the human body from the catabolism of heamogolbin leading to an endogenous formation of 0.3-0.8% COHb in blood . Cont…
CO - Some Facts Bhilai Steel Plant • The appearance of CO affected symptoms depends on the CO concentration in the work zone air, duration of exposure, degree of exertion and individual susceptibility. • CO causes headache, nausea, dizziness, vomiting, chest tightness. • Reduces O2 supply in vital organ like Brain, Lungs and Heart. • Exposure to concentration of 10,000-40,000 ppm leads to death. • TLV 50 ppm for 8 Hrs. • STEL 400 ppm within 15 mts.
Gas Dynamics in CO Poisoning Bhilai Steel Plant Heart Normal Health O2 Air (O2) Oxyhemoglobin Muscle O2 Heart X CO Poisoning O2 O2Hb+CO Carboxyhaemoglobin (COHb ) Muscle X O2
Health Effects at Various CO Saturations Bhilai Steel Plant SYMPTOMS % SATURATION 10-30 % Headache, Drowsiness, Nausea, Vomiting, Increased Respiration and Pulse rate , ECG ST segment depression 30-40 %Increased Pulse rate, Decreased Blood Pressure, Cardiac Arrhythmias , Muscular incoordination 40-60 %Mental confusion, Marked Weakness, Increases pulse rate even victim may collapse > 60 % Unconsciousness, Convulsions and Death
Relation between Exposure & Health effects Bhilai Steel Plant Source – ILO encyclopedia of OHS
Reasons for undertaking this study Bhilai Steel Plant • There were no spectrophotometric method in use for COHb estimation in blood, although there is a probability of CO poisoning cases in steel plant. • CO in exhaled air (PPM) & COHb% in blood are comparable but this is a rough guide & does not give accurate COHb estimation. • spectrophotometric method is accurate, color formed is stable and gives correct estimation of CO saturation in blood. • CO poison cases are very often reported in MMP.
Objective Bhilai Steel Plant • To evaluate the work place CO concentration. • To assess carbon monoxide related subjective symptoms with the level of exhaled air CO(ppm) and COHb% among study group. • To suggest control measures to mitigate the associated health problems.
Method Bhilai Steel Plant • Measurement of CO concentration in work zone by using CO monitor & aspirator (66 locations) • Exhaled air CO estimation by smokerlyzer (BEDFONT).
Method Bhilai Steel Plant • COHb estimation in blood samples by using HACH spectrophotometer at EnMD laboratory. • Structured questionnaire survey, data compilation, analysis, comparison with non-exposed group.
Method Bhilai Steel Plant • Precision of spectrophotometric method by replicate analysis • SD - ± 0.25 & RSD - 0.89 % • Study period May’2014 to Nov’2014.
Study Profile Bhilai Steel Plant Pie diagram Exposed (n=61) group like BF, CO battery, ARS Non Exposed (n=50) group like Medical, Education, Personnel
Observation Bhilai Steel Plant Table - 1 Level of CO at different locations
Observation Bhilai Steel Plant Table - 2 Working Environment CO & COHb levels among Exposed & Non-exposed
Observation Bhilai Steel Plant Table - 3 Comparison of Smoker & Nonsmoker Subjects among Exposed Group
Observation Bhilai Steel Plant Table - 4 Health Symptoms among Exposed & Non exposed
Inference Bhilai Steel Plant • Work zone mean CO concentration in coke oven 22.0(5.4), BF 16.0(4.2), ARS 27.0(3.6). • The above concentration were influenced by the process in the respective sections. • In Coke Oven - Cellar/Heating section, BF - Dust Catcher, Stove, Cast House, ARS – Vehicle service station covered under the study. • Mean COHb level among non-exposed group observed to be (3.82 ±(1.22) less than NIOSH recommendation of 5% COHb Cont…
Inference Bhilai Steel Plant • Exposed employees had higher COHb% comparing to non-exposed (p<0.01). • No significant difference in COHb% among smoker & non-smoker in exposed group. • Increase in CO concentration in work place results into increasing COHb among employees. • Headache, Dizziness were the prevalent symptoms. • These symptoms significantly correlate with the presence of CO in the work place.
Recommendations Bhilai Steel Plant • Use of approved respirator & pocket CO monitor. • Provision of online CO monitor in all the probable hazardous locations. • Periodical Medical Examination of the CO exposed workers to include exhaled air CO estimation on regular basis. • Health education communication, Gas danger caution board. • Follow up of employees having history of COHb level.
Conclusion Bhilai Steel Plant • There is a need to implement effective engineering control measures in the work place. • Spectrophotometric method for COHb estimation is best and accurate to be practiced in Steel Plant.
References Bhilai Steel Plant • Methylene chloride exposure and Corboxyheamoglobin levels in cabinet maker, sunny O.Banjoko,K.C. Sridhar, In.J. of Env.Med. • p-56-60 Vol.-II, May-Aug:2007. • Van Kampen E.J., Zijlstra W.G., Determination of Heamoglobin & its derivatives , Clinical Chemistry Vol. 8, p 141-47 : 1965 • Forbes W.H; Sargent F; The role of CO uptake by normal man. Am.J.Phy.sc.,143 p 594-608 :1995