Lung-busters 3M describes common workplace threats to the human respiratory system and how to combat them. In the modern industrialized workplace, there are many threats to the human respiratory system. Millions of workers around the globe are exposed on a daily basis to an extensive array of chemicals, powders, gases, vapors, fumes and airborne contaminants. Fortunately, conditions have improved since the early days of the Industrial Revolution, when there was little or no concern for the health of the workforce, and many workers died as a result of over-     exposure at work.                                                                                                  All humans need a supply of air to survive, and the human lung is the means we use to extract life-giving oxygen from the air and to exhale waste carbon dioxide. Efficient respiration requires two healthy lungs to absorb the oxygen we need. The airways divide more than 20 times into smaller and smaller branches so that we end up with around 300 million alveoli and a total oxygen-absorbing surface as large as a tennis court! The human lung has developed during millions of years of evolution and nature has incorporated a number of defense mechanisms to give us some protection from naturally occurring airborne contaminants. Things like nasal hairs, mucous linings and the many twists and turns through the airways are mechanisms used to trap contaminants before they get to the delicate oxygen exchange areas, called the alveoli, deep in the lungs. We are all familiar with the coughing response that occurs when we get a high input of smoke or other respiratory irritants like ammonia. This is the body reacting to an over-exposure and helps expel the contaminant as quickly as possible from the lungs. Smoker’s cough is the body’s response to an excess of mucous containing foreign particles (smoke and ash) from the lungs. The small hairs (cilia) that do this job in a healthy lung are killed off over time by over-exposure to tobacco smoke and the cough reflex is used to force the mucous in the airways up and out of the lungs. Mother Nature has given us a level of protection against naturally occurring levels of materials like dusts and pollens, but not against many of the concentrated man-made materials used commonly in the modern workplace. Many gases and vapors that can do damage to our lungs or other organs cannot be detected by sight, smell or taste and we may be unknowingly over-exposed when using these substances. Sadly, we have learned that some materials, like asbestos, after exposure to levels that are not visible in many cases, will cause lung disease and premature death to workers, and even their families. Providing respiratory protection for workers is part of the duty of care of the employer in the modern industrial situation. Employers are required to use appropriate means to prevent health hazards to the workers. This includes measures like use of low-toxicity materials, provision of engineering controls like extract ventilation and enclosures and, as a final resort, the use of personal protective equipment. Respiratory protection is necessary in many workplace situations because engineering controls are not available, are impractical or are too expensive to implement in the short or medium term. Each workplace will have its own problems and hazards and will require assessment by a suitably qualified person to determine if there is a need for respiratory protection and, if so, what type and specific applications are needed. There are a number of basic requirements for assessing a respiratory hazard. The first is to identify the contaminant and to quantify the amounts of the airborne contaminant in the working environment. In some cases, this may require the use of an occupational hygienist, who will have the knowledge and equipment to measure the airborne concentrations of the materials in question and make informed recommendations as to the appropriate responses to the hazard. The contaminants, or “lung-busters”, in a workplace can include: “Nuisance” dusts – small particles that clog up the airways of the lungs and create discomfort and breathing difficulty, for example, flour. Toxic dusts – particles that are toxic to the body and can cause local or remote effects to the body after being inhaled into the lungs, for example, asbestos. Irritant gases – gases that are water-soluble and cause irritation to the upper respiratory tract, for example, ammonia. Asphyxiants – gases that interfere with the supply of oxygen to the body. They can be simple, such as an inert gas like nitrogen that dilutes the oxygen in the air to a dangerously low level. Or they can be chemical asphyxiants like carbon monoxide or hydrogen cyanide, which are taken up into the bloodstream in preference to oxygen and the body’s organs shut down due to lack of oxygen. Anesthetics – many organic solvents, for example, petrol, ethanol, benzene, are absorbed from the lungs into the bloodstream. They are then carried around the body and can cause damage to organs such as the brain and the liver. They can depress the operation of the central nervous system and cause paralysis and death. Sensitizes – these can cause allergic reactions like asthma, after an individual is exposed and is sensitized, for example, isocyanates. After identifying the type and size of the respiratory hazard, suitable respiratory equipment for these conditions should be identified. Normally there will be a number of options, depending on the local conditions, wear time, cost and other factors that will help to decide the appropriate equipment. Sometimes, there will be state regulations that require a certain type of protection for a specific material; for example, spraying isocyanates must be done wearing an air-line system with clean air from a compressor or air bottles.