Breathing air systems and ventilation air systems provide reliable and safe air supply sources to workers in hazardous industrial environments. There are many different types of breathing and ventilation air systems. Examples include air filtration systems, air ventilation systems, industrial ventilation systems, and air purification systems. An air filtration system is designed to improve the quality of the air in an industrial unit by removing dust, pollen, smoke, and other airborne toxins and irritants leaving the air being breathed cleaner and healthier. An air pollution control system is a specialized dust control system for the asphalt, cement, food, grain, mining, and timber industries. An air ventilation system cycles fresh air through a building. An industrial ventilation system limits worker exposure to airborne toxic chemicals or flammable vapors by exhausting contaminated air away from the work area and replacing it with clean air. A fresh air breathing system includes a high-efficiency filtration system that delivers breathable air at high flow rates with safe, low pressure. An air purification system includes an activated carbon canister and integral blower with odor control and VOC control. Other breathing systems are also available. Breathing air systems and ventilation air systems include a filtration system that provides breathable air with appropriate pressurization and ventilation. Outside air from 50 CFM to 100 CFM can be introduced, providing from 72,000 to 144,000 cubic feet of air into the indoor environment everyday. This allows for pressurization of the indoor environment, eliminating the entry of fine particulate, gases and odors whenever an HVAC system is running. Specialized machinery is used for particulates over 5 microns. It is important to balance the explosive gas ventilation system during the detection of gas leaks so that leaks can be diluted and removed from the enclosure. Many breathing and ventilation air systems have control scrubbers for chemical nitration, combustion sources, metal finishing operations and virtually all generators of NO and NO2. Breathing air systems and ventilation air systems are used in many different industries and applications. For example, an air intake system can be used in an oil refinery, petrochemical plant, or pulp and paper mill. An air system can also be used in facilities that manufacture steel, metals, and glass. Some breathing systems are used to replace carbon dioxide gas with fresh air. These air intake systems play a significant role in reducing potential allergens that might affect personnel with respiratory problems. In industrial settings, breathing and ventilation air systems are often used to remove welding fumes, solvent vapors, oil mists, or dust. Breathing air systems and ventilation air systems adhere to standards from the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE); the U.S. Occupational Safety and Health Administration (OSHA), and the U.S. Environmental Protection Agency (EPA). Breathing systems that meet Maximally Achievable Control Technology (MACT) standards as well as other state and local emission standards are also available.