Most odors from medical facilities are not dangerous to physical health; instead, they are considered psychological nuisances. The same goes for areas where medical waste is stored or processed. An industrial hygienist or waste management professional should evaluate whether a given batch of waste is dangerous as far as infection or toxic fumes, but if it isn’t, there might still be an odor.
The level of nuisance is subjective and a matter of human judgement. In establishing whether there is a strong odor there are two approaches: olfactometry and analytical. Olfactometry means one or more people say whether the odor is strong, and try to characterize it, which may provide a clue to the source and to a means of mitigation. Analytical methods use gas chromatographs and mass spectrophotometers to analyze vapor concentrations. These methods require equipment that can be expensive, but that equipment can monitor the area 24 hours per day.If the gas causing the odors is soluble in liquid, mechanical devices called scrubbers can water wash air to remove the odorous substances. Scrubbers are widely used to remove hydrogen sulfide and halogenated compounds.
Depending upon the air composition, an oxidizing agent, an acid, or an alkaline substance could be added to the water to increase the efficiency of the washing operation. Absorption equipment is made available in different forms from packed towers packed with spiral, hollow or Rasching rings; simple vertical spray towers; cyclone or centrifugal scrubbers.
Adsorption differs from absorption; the target gases are trapped and retained on the surface of a solid adsorbent made of porous material. This process involves passing the gas through a filter containing the absorbent material. Silica gel and activated carbon are common odor-control adsorbents used in medical waste facilities.
Adsorption is arguably the most straightforward technique to remove odors; it is fairly passive. Due to their simplicity adsorption units are also used in combination with other techniques.
Vegetative environmental buffers (VEBs) are areas created around the industrial buildings with planted trees. Ecological shields reduce odor and dust in two ways. They intercept, absorb, and break down odorous substances by acting as biological filters. Secondly, they decrease the airspeed by acting as wind barriers, resulting in reduced dilution of odorous substances. Professionals recommend diversifying the species of trees with ones of different growth rates.
In odor masking, the unwanted odor is suppressed by using a stronger and pleasant smell or a combination of smells. The masking agent does not change the chemical composition of odor, it only superimposes a new smell. This technique requires significant technical knowledge and analysis to formulate an effective odor control strategy, so it has no room for amateur experimentation.
Combustion units oxidize odorous substances into non-smelling or less odorous compounds such as water and carbon dioxide. This method is usually employed in highly energy-intensive industries. For example, if the plant has a boiler, the air required for the boiler can be odorous exhaust air.
