Always use good ventilation and RPE (respiratory protective equipment), including work outdoors.
For light and/or sporadic welding with MIG,MAG,FCA,MMA and gas welding processes, a mixture of excellent ventilation and RPE is that the “best practise” approach to require. Even when outside RPE should be employed by the welder to avoid direct inhalation of fumes. Click here for samples of Respiratory Protective Equipment.
Use an LEV system like a mobile filter where practicable.
A common sense approach should be taken here, put yourself within the shoes of the inspector – if you could/should be using an LEV system (where conditions/location allow), are you? it's always better to be safe than sorry! you may also must make sure the unit has the right kind of filter for your work.
Special filters are required for grinding jobs for instance and HEPA filters may be required for a few applications.
For regular and/or high intensity welding with MIG/MAG/FCA/MMA and gas, LEV is usually required. Supplementary RPE should even be considered for personnel within the working area.
Any situation that might be deemed as “high risk” – i.e production workshop environments and frequent welding, an LEV system are going to be required. this might be within the shape of mobile filters for welding bays, or a set system with ducting to the most filter reckoning on usage and applications. it's also advisable that personnel working within the vicinity of the welding area should wear RPE.