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MSHA, therefore, requires that noise levels be reduced below 115 dB TWA. If noise levels exceed 115 dBA, miners are required to wear hearing protection. MSHA requires that administrative and/or engineering controls must be implemented in the workplace when miners are exposed to levels above 90 dBA TWA. Mine Safety and Health Organization (MSHA) OSHA also requires that impulse noises and impact noises must be controlled to prevent these noises reaching past 140 dB peak sound pressure levels (SPL). OSHA's requirements state that when workers are exposed to noise levels above 90 A-weighted decibels (dBA) in 8-hour time-weighted averages (TWA), administrative controls and/or new engineering controls must be implemented in the workplace. Occupational Safety and Health Administration (OSHA) Organizations each have their own standards, recommendations/guidelines, and directives for what levels of noise workers are permitted to be around before noise controls must be put into place. Standards, recommendations, and guidelines Sound masking is the active addition of noise to reduce the annoyance of certain sounds the opposite of soundproofing. Industrial noise control is a subset of interior architectural control of noise, with emphasis on specific methods of sound isolation from industrial machinery and for protection of workers at their task stations. Many of these techniques rely upon material science applications of constructing sound baffles or using sound-absorbing liners for interior spaces. These techniques include design of exterior walls, party walls, and floor and ceiling assemblies moreover, there are a host of specialized means for damping reverberation from special-purpose rooms such as auditoria, concert halls, entertainment and social venues, dining areas, audio recording rooms, and meeting rooms. In the best case of project designs, planners are encouraged to work with design engineers to examine trade-offs of roadway design and architectural design. Multiple techniques have been developed to address interior sound levels, many of which are encouraged by local building codes. Social activities may generate noise levels that consistently affect the health of populations residing in or occupying areas, both indoor and outdoor, near entertainment venues that feature amplified sounds and music that present significant challenges for effective noise mitigation strategies. Roadway noise and aircraft noise are the most pervasive sources of environmental noise. The main areas of noise mitigation or abatement are: transportation noise control, architectural design, urban planning through zoning codes, and occupational noise control. 2.5 European Parliament and Council Directive.2.2 Mine Safety and Health Organization (MSHA).2.1 Occupational Safety and Health Administration (OSHA).2 Standards, recommendations, and guidelines.