4.2.1.1 Environments/conditions likely to cause heat or cold
stress or injury.
4.2.1.2 Environments requiring ear protection due to noise
4.2.1.3 Explosives or articles containing explosive components
4.2.1.4 Radioactive substances including any exposure to
radium, self-luminous compounds, thorium salts, and
ionizing radiation in excess of 0.5 rem per year as per
US Department of Labor guidance.