Older brake pads or shoes may contain asbestos, which has been determined to be a cancer causing agent. Never clean the brake surfaces with compressed air! Avoid inhaling any dust from any brake surface. When cleaning brake surfaces, use a commercially available brake cleaning fluid.
See Figures 1, 2, 3, 4 and 5
Fig. Fig. 1: Front disc brake components-Excel, Scoupe and Accent
Fig. Fig. 2: Front disc brake components-Elantra, Sonata and Tiburon
Fig. Fig. 3: Rear disc brake components-Tiburon and 1996-98 Elantra
Fig. Fig. 4: Rear disc brake components-Sonata
Fig. Fig. 5: Front disc brake components