Local Exhaust Ventilation (LEV) is a control measure that aims to reduce or minimise exposure to hazardous substances, so regular testing is necessary. The COSHH Regulations 2002 (as amended) oblige companies to have their LEV systems that are in place to control hazardous substances to be checked. Thus, it is the law even when you carry out the necessary regular maintenance and cleaning.  Regulation 9 (2) deals with formal maintenance and states that a thorough examination and test of all systems needs to be carried out at least every 14 months. Some systems that handle more hazardous substances such as those that can cause cancer or asthma (as per Regulation 6 or Schedule 4) have to be tested more often as the risk of ill health is higher when the LEV fails.

The testing measures a range of parameters and visually inspects the full system and how it is used by workers. The LEV survey checks that it is working correctly, effectively and doing the job it should.  The report highlights defects and any areas for improvement to the site. The HSE guidance book HSG258 outlines more detail on this subject and how test should be undertaken and gives a list of checks that the site can do themselves in the interim.