Cardio-respiratory studies on glass bangle workers.

Cardio-respiratory functions were recorded in 18 glass bangle workers (Belanias) who worked near the belan furnace continuously for 2 h. The workers were exposed to high ambient temperature (tDB 38.2 degrees C +/- 3.4 degrees C) and thermal radiation (tG 46.2 degrees C +/- 5.1 degrees C) during their work. The physiological responses recorded after the work spell at 1 (R1) 3 (R3) and 5 (R5) minute intervals exhibited incomplete recovery. The oral temperature remained significantly high (0.74 degrees F +/- 0.27 degrees F) even at R5 and never reached pre-work value. Similarly the heart rate values remained very high (26.4 +/- 5.4 beats/min) at R1, (10.7 +/- 3.9 beats/min) at R3 and (4.01 +/- 2.4 beats/min) at R5 periods during recovery, thereby showing that heart rate did not regain the pre-work status. The incomplete recovery in heart rate revealed cardiac stress in the exposed workers. Besides the cardiac stress, the cardiac cost of the work under the prevailing hot conditions in the glass bangle industry was very high, adding further to circulatory strain in these workers. Almost all the exposed workers were found to have hyperventilation syndrome characterized by increased respiratory frequency and tidal volume resulting in ventilatory stress induced by physical and physiological heat.