environmental hygiene
environmental hygiene
By Richard Dixon
Engineered Infection Prevention : A New World of Better Disinfection of Air , Water and Surfaces
Most people in the Middle Ages believed the world was flat . Brave adventurers such as the Vikings sailed across the ocean to the Atlantic seaboard , and the Chinese journeyed across the Pacific . They began the process of challenging this supposition . It then took several hundred years of voyages of discovery to map out the perimeter of North and South America in addition to inland expeditions such as the mapping experiences of Lewis and Clark in the U . S . and the Hudson Bay Company in Canada to define the nature of this vast land mass .
We do now believe the earth is round , humans have set foot on the moon , probes have landed on Mars , and a trip on a Boeing 787 Dreamliner from Seattle to Paris takes only 11 hours while we sit in comfort sipping a glass of wine . The moral of this story is that new ideas take time to become accepted , practiced , become the new normal and pave the way for the next new idea .
Many healthcare-acquired infections ( HAIs ) are caused by building-related environmental impacts of air , water , and surfaces , such as high-touch surfaces containing bacteria that are potentially harmful to patients and their subsequent transmission by people from surface to surface . Aerosols can also act as vehicles of microbial transmission . While we once thought medical procedures generated large amounts of aerosols , we now know that common actions like talking , shouting , singing , and coughing , generate far more aerosols than any medical procedures . Even the simple act of flushing the toilet can liberate dangerous pathogens with every use . Recent articles have nicely illustrated that aerosols from toilet plume can be potential vehicles for Clostridioides difficile and norovirus with deposition of infectious particles on bathroom or patient room touch surfaces . While handwashing and daily environmental cleaning have been the mainstays of environmental infection control for the past 170 years , today ’ s healthcare environments need new innovative processes in the battle with newer , more aggressive bacteria , viruses , and molds , such as the emerging threat of Candida auris .
The new ‘ round ’ world is about the use of engineered infection prevention ( EIP ) technologies , materials , automation , and strategies that are adjuncts or even replacements for traditional disinfection of air , water , and surfaces . One of most important risk assessment tools today is the quantitative microbial risk assessment ( QMRA ) 1 :
� What level of bacteria / virus reduction is needed to result in a significant risk reduction ? � What routes of exposure cause the greatest risk of infection ? � What activities cause the greatest amount of exposure to pathogens ?
� How do pathogens spread via hands and surfaces and aerosolization in different environments ? E . g ., hospitals , outpatient clinics , urgent care , long-term care , etc . � Where does the greatest exposure occur ? � How effective are hygiene products in reducing infection risks ?
� What is the impact of the number of persons in a facility that practice good hygiene on the other persons in the facility ( herd hygiene )?
� What is the impact of a product or process in practice on disease transmission in each environment ?
� What is the cost / benefit assessment of prevention interventions ?
The tendency to reject new evidence or new paradigms such as EIP because it contradicts established norms , beliefs or paradigms is ironically known as the Semmelweis Reflex . 2 Ignaz Semmelweis , of course , went to his grave unable to convince his fellow doctors of the need for hand hygiene to prevent HAIs .
Here are some practical , safe , cost-effective and sustainable examples of EIPs in our new ‘ round ’ world .
Germicidal ultraviolet ( UV-C ) light is a common type of UV well known for one hundred years for its ability to disinfect bacteria , viruses , and mold . Covering the span of invisible light from 200 to 280 nm , the most common and cost-effective wavelength is 254 nm . UV-C photons fuse neighboring thymine and cytosine molecules on DNA strands , thus preventing replication .
UV-C disinfection is commonly used for :
● 1 . Water : a . Water treatment b . Wastewater treatment . c . Potable drinking water systems d . Ice machines
● 2 . Air : e . “ Coil Cleaners ” - Industrial and hospital HVAC air handling units to prevent mold , bacteria and biofilm formation in cooling coils , filters , and evaporation pans ; very inexpensive and energy-efficient . f . “ In-Duct ” - Hospital and office tower in-duct air disinfection systems designed to reduce pathogens , especially in recirculated air , which cause HAIs and Sick Building Syndrome , typically up to 99 percent . g . Air Purifiers – Either stand-alone devices or located within devices downstream of HEPA or other filters ; often ceiling-mount or portable ; typically , 99 percent or higher reduction . h . Upper Air Disinfection - UV-C fixtures installed near the ceiling to create a field of UV-C across the upper part of a room ( above 7 ’ 6 ”). The efficiency of the system can be enhanced with ceiling fans that actively draw air into the UV-C field and circulate the air throughout the room .
● 3 . Surfaces : i . Mobile – Typically one , two or three UV-C towers on wheels that are manually placed in unoccupied rooms to disinfect spaces between occupancies ; especially used in hospitals for “ terminal cleans ”
22 november 2023 • www . healthcarehygienemagazine . com