Noise is subdivided into environmental (road, rail, air transport noise), neighbourhood (people and activities such as pubs, clubs, barking dogs and music lessons) and neighbour noise. The Environmental Noise Directive (END) concerns noise from road, rail, air traffic and industry. It focuses on individuals' exposure to noise emissions from specific sources. Environmental noise monitoring assessments are carried out for planning applications and activities that generate invasive levels of noise. Noise levels and its effects Industrial noise or noise at work is usually considered in terms of environmental health and safety, rather than nuisance. This is because sustained exposure causes permanent hearing damage. Noise causes hearing impairment (at long-term exposures of over 85 decibels (noise levels dB), known as an exposure action value). It is a factor in stress and raises systolic blood pressure. Noise can be a causal factor in work accidents. How? By masking hazards and warning signals, and impeding concentration. Personal protective equipment for noise monitoring A dosimeter, used for monitoring an individual during the working day, can be used where it is difficult to measure with a hand held sound level meter. The use of hearing protection should only be considered once all practical measures to reduce noise in the workplace have been implemented. A methodical noise control and sound measurement approach reduces noise at source. Two main types of hearing protection are ear muffs and ear plugs. The need for personal protective equipment will be determined by sound testing, a noise test and a noise monitor.