The present guideline serves to improve the hygienically acceptable indoor-air quality in occupied areas in waste treatment plants by means of ventilating and air-conditioning systems. The term "occupied area" is taken to denote "permanent workplaces" as defined in LV 15 (see Section 2). The guideline specifies the requirements to be met in planning, erecting and operating facilities and technical posal are stored, treated and/or transhipped. Landfills (dumpsites) and temporary storage facilities outdoors and underground are excluded from the scope. Neither does the present guideline apply to the facilities specialised in the processing and disposal of animal carcasses, or in the recycling and disposal of radioactive materials or so-called "wastes requiring particular monitoring". This guideline does not deal with the environmental effects of exhaust-air installations, nor with ambient sound or noise indoors. systems within the specified scope and describes state-of-the-art measures to be taken in order to ensure the required indoor-air hygiene in occupied areas. This guideline addresses, in particular, architects, building owners, consulting engineers, plant manufacturers, approving and inspecting authorities, experts, operators, maintenance personnel, users and those representing their interests, such as staff or workers' councils, employers' liability insurance associations as well as company physicians and public health officers. The present guideline applies to the planning, erection and operation of waste management facilities and plants where wastes for recycling and for disposal are stored, treated and/or transhipped. Landfills (dumpsites) and temporary storage facilities outdoors and underground are excluded from the scope. Neither does the present guideline apply to the facilities specialised in the processing and disposal of animal carcasses, or in the recycling and disposal of radioactive materials or so-called "wastes requiring particular monitoring". This guideline does not deal with the environmental effects of exhaust-air installations, nor with ambient sound or noise indoors.