The purpose of a welding curtain or screen is to protect passers by and nearby workers from the welding arc light. Where welding takes place and other people are likely to be close-by, there should be something in place to prevent them being affected by the light. In practice this protection is often achieved by using curtains or screens.
Flame retardant, heavy canvas screens are very common however many people prefer to be able to see if someone is welding inside. This means that many screens are made of 'semi-transparent' plastic. These semi-transparent screens allow you to see enough to know that someone is welding, but the material filters out the harmful parts of the light. If there is no need to see the person welding or for screening in between welding bays, darker or opaque screens and curtains should be used.
Welding curtains and screens should conform to the British Standard (BS EN 1598) or at least offer the same level of protection as this Standard. Some welding equipment suppliers may refer to this as "EN 1598". The Standard does not specify any particular colour it just requires the curtain to attain certain levels of performance. This means that suitable curtains may be available in a variety of colours and levels of 'darkness'. A reputable supplier should be able to confirm if a curtain conforms to the British Standard. At the moment, HSE is not aware of any clear welding curtains that conforms to the BS EN 1598 standard.
Is this something I should have and should my employer provide it?
Pneumonia is just one of the ill health risks if exposure to welding/metal fume is not adequately controlled, so avoiding exposure is always the first step. More information on the vaccination is available and also for controlling fume and Fume facts - What is it and what does it do to you.