## 8 Solutions Used Around the World
The regulations are based on various aspects [128]:  
* odour limits depending on the odour threshold of the substance;
* use of dynamic olfactometry for emission measurements and dispersion modelling,
* changes to urban planning, designation of areas in which a potentially nuisance industrial plant may not be located;
* the establishment of a standardised register of citizen complaints and, on this basis, the limitation of areas in which an industrial installation that may cause odour nuisance can be located;* mathematical studies that take into account the following: odour concentration, hedonic intensity, odour duration, periodicity, wind direction, etc. ;
* the application of a method based on field inspection [126]. In Germany, odour nuisance is regulated by Section 3 (1) of the Federal Immission Control Act [33,128]. Odour pollution in the environment is determined on the basis of the so-called odour hour by recording the odour above the detection threshold and determining its frequency (number of odour hours per year) [128]. The analyses are carried out on the basis of measurements in a grid (standard EN 16841 part 1 [126]) or as a result of dispersion models. In Italy, several regional laws have been published (Lombardy, Trento, Piedmont) whose regulations are based on dynamic olfactory and dispersion modelling. In Puglia, the situation is slightly different, the criteria are based on the sensitivity of the people within their reach. Sensitivity is categorised into eight different groups: from areas where hospitals are located (restrictive level) to industrial or agricultural areas [128]. Although Directive 2010/75/EU of the European Parliament and of the Council of 24 November 2010 on industrial emissions [124] aims, among other things, to control odour emissions, there is unfortunately no direct implementation of this initiative in the official regulations of most European countries due to analytical problems. In East Asian countries, there are also regulations for odour emissions in addition to the requirements set at the \"receiving point\". In China, there are standards for both organised and non-organised sources. In Japan, there are general national regulations, but also more detailed regulations at the local level. Local authorities have the right to choose one of two regulations: based on odour indicators or odour concentrations [33]. In the United States, the Environmental Protection Agency (EPA) does not regulate odour as a pollutant. Individual states and local jurisdictions have attempted to regulate it. The most common method for regulating odour is field olfactory. It is used by ten states [33]. Ten US states regulate agricultural odours directly. Thirty-four states have regulations and guidelines to limit emissions, such as: Distance to Emission Point, Manure Management Plan, Permits, Land Application of Fertiliser Regulations, Manure Application Training, etc. In Canada, there are no regulations for odours from industrial and agricultural facilities. There is also no standard method for assessing odours. The most common approach is to measure the odour source using dispersion models to predict off-site odour concentrations. However, odour can be treated as a pollutant that has an adverse effect and is therefore subject to regulation (e.g., NH\({}_{3}\), H\({}_{2}\)S or other reduced forms of sulphur). There are also a variety of approaches to regulating odour management in Latin American countries. Chile is currently introducing a number of measures based on olfactometric studies to develop regulations for various industries, e.g., pig farms, fisheries and fish processing, wastewater treatment plants, the pulp industry or landfills. Colombia has also started to regulate the method for determining odour concentration using olfactometric methods. A resolution has been drawn up setting limits for odorous substances such as H\({}_{2}\)S, reduced sulphur content (TRS) and NH\({}_{3}\). The main objective of odour regulation is to promote good environmental practices [33].