## 8 Solutions Used Around the World  
Possible differences of opinion on the methods used to measure odorous substances lead to difficulties in developing a common approach to odour control policy. In European Union countries, odour is regulated by Directive 2010/75/EU of the European Parliament and of the Council of 24 November 2010 on industrial emissions [124]. It is supported by standards on measurement methods, e.g., for dynamic olfactometry [125] and on-site inspection [126]. It establishes general principles for setting odour limits for many types of industrial activities. The control covers, for example, the energy industry, metal production and processing, waste management, the chemical and mineral processing industries and agriculture (e.g., animal husbandry). Installations in this area of activity may be operated if they have a licence whose conditions are defined in such a way that a high level of protection for the environment as a whole is achieved. They are generally based on the concept of best available techniques (BATs). In order to determine BATs, reference documents for BATs (so-called BAT reference documents) are drawn up [33,127]. The emerging BREFs also contain a new value for the emission levels associated with the best available technology (AEL BAT), which defines a set of emission limit values for each installation applying for a permit [33]. However, the BAT reference documents are neither prescriptive nor exhaustive and do not exempt national authorising authorities from carrying out assessments for specific sectors. In several European countries, there are also other legally binding documents and guidelines on odour. These provisions are most commonly used when detailed criteria are not specified in the BREF or when they are missing. In France, in addition to the general odour control regulations based on the Industrial Emissions Directive, there are specific odour control regulations for two types of activities: animal by-products processing plants and composting plants. The legislation uses odour concentration values measured according to the EU standard EN 13725 and the frequency of occurrence of odours. The regulations also concern the frequency of measurements [33]. In Austria, there is no law regulating odour nuisance at a national level and odour nuisance is regulated qualitatively (e.g., unacceptable odour is not permitted). The Industrial Emissions Directive only applies to a few types of industrial activities. However, specific odour limit values based on olfactometric tests and modelling apply to some installations that generate odours. For example, in the livestock directives, a certain distance between the installation and areas inhabited by humans (distance) is defined using a dispersion model. It is determined on the basis of emissions from livestock facilities estimated from the number and type of animals, the ventilation system, manure removal or storage and the type of animal feed [128]. Similarly, in Bulgaria, there is no law regulating odour nuisance at national level. Here, only the emissions of certain odorous substances (e.g., hydrogen sulphide) are regulated, without reference to their odour characteristics [128]. In Spain, some municipalities have decided to develop their own odour control regulations (Barcelona, Girona, Alicante, Murcia, Canary Islands). These regulations are usually focussed on a certain type of establishment. Local regulations are also drawn up, e.g., for bars or restaurants.