If your portable air compressor is operated safely and is well maintained, it will be safe. However, if it is mistreated and malfunctions as a result, it could pose a significant danger that may result in injury to the people working in the surrounding area as well as damage to the compressor and anything in the surrounding area.
Human safety – While it is tempting to play with the compressed air, it is expelled at extremely high pressure which, if it comes into contact with a person, could cause serious bruising or an eye injury. The smaller portable compressors emit air at 90 PSI, the larger ones could expel it at up to 150 PSI – the breaking point of skin is 100 PSI and, crucially, the eye can sustain a significant injury at only 12 PSI. This is why you must always wear safety glasses while operating any air compressor.
Compressor safety – The pressurised air inside the air compressor is highly flammable, so any kind of spark could lead to an explosion. It is therefore necessary to check there are no oil leaks, to keep the compressor away from combustible or flammable materials, and to minimise the risks of electrical shorting in the compressor as well as other equipment in your workshop.