This standard describes procedures for sampling fumes and gases generated by welding and allied processes. Because it is limited to health hazard evaluation@ the standard is primarily concerned with sampling at the worker??s breathing zone (see 4.1). It also describes procedures for general area sampling of fumes and gases. The sampling methods described in this standard apply to the sampling of solid particulate matter as well as the gases liberated during welding and allied processes. Gases generated during welding may include@ but are not limited to@ the following: (1) Ozone (O3) (2) Carbon Monoxide (CO) (3) Nitric Oxide (NO) + Nitrogen Dioxide (NO2) = Oxides of Nitrogen (NOx) (4) Gaseous Fluorides This publication is intended for use by personnel who are responsible for sample collection and evaluation of the environment of personnel involved with welding and allied processes. It provides the most widely recognized@ safe methods for the sampling to be used in the evaluation of airborne concentrations of fumes and gases commonly formed during welding. Where appropriate@ analytical methods have been referenced. While not generally present around most welding operations@ it is possible to encounter toxic phosgene gas where degreasing or cleaning activities involving chlorinated hydrocarbons are carried out in close proximity to welding. Antispatter compounds may also contain chlorinated hydrocarbons. When vapors from these materials enter the atmosphere around the arc@ a reaction between ultraviolet radiation from the welding arc and these vapors can produce phosgene. Since phosgene levels as low as 2 ppm can cause serious health impairment or even death@ it is important to prevent vapors from any chlorinated hydrocarbon from entering the welding area. Consult the Safety Data Sheet (SDS) for any cleaning products used in close proximity to welding processes. Sampling for phosgene is outside the scope of the procedures described in this standard. This standard makes sole use of the International System of Units (SI).