IAQ is by far the most often ignored of the three ways to transmit disease in health care facilities (the other two being surfaces and human contact).
What does IAQ stand for? Indoor air quality. Doctors, infection prevention nurses, and maintenance & engineering department heads are slowly coming around to the idea that hospital air control is just as important as managing surface disinfection and human contact.
How is airborne disease transmitted in hospitals? Through airborne pathogens.
So many documents tell you what they are and what illnesses they cause, but few if any centralize all the crucial facts about health care-associated infection (HAI) control in one place.
We’ve done that for you here.
Pathogens in the air are spread on particles or droplets. The solid matter may come from human skin scales, while the droplets may be generated from:
Upper and lower respiratory tract
Dripping water taps
Small respiratory droplets start to evaporate after release and then change their size, resulting in droplet nuclei that are sufficiently small to remain suspended in the air for long periods of time — and still be infectious.
Respiratory droplets can be spread by:
Artificial means of producing potentially infectious aerosols in hospitals include using respiratory assist equipment such as:
Survival of pathogens in the air depends on their amount of time in the air as well as ambient environmental factors, like temperature and humidity. The transport of airborne droplets is affected by:
Local ventilation air flows
Movement of people
Thermal gradients produced by various electrical equipment
Another factor is receptors in human host cells. Differing patterns of receptor distribution between different individuals in the upper and lower respiratory tracts will affect the ease with which inhaled airborne viruses can cause infection and disease.
The nature of the infecting agent and human respiratory activity itself may cause a different variety of pathogen to be expelled, with differing effects on secondary cases.
Coughing brings up deep-seated pathogens from the lower respiratory tract in the chest. These can include species of:
Tuberculosis can be a source of outbreak in hospitals. Health care workers infected with TB can spread infection widely, requiring extensive screening of patients and staff.
Norovirus, transmitted through the air, is difficult to contain in a hospital ward without sufficient single rooms with en suite toilets.
To ensure sufficient dilution of bacterial load around an infected patient room, air should be changed 10-20 times every hour. This is difficult to maintain with ventilation systems especially in negative pressure rooms. More on that below.
MRSA can survive on skin scales for up to 80 days, and spores of Clostridium difficile may last even longer. MRSA can travel in the air on these smaller skin scales for the length of a ward. Minimal colonization of these bacteria on open wounds and mucous membranes can cause significant infections
Testing occurred in a very small test chamber or non-full-size room.
Testing happened in a non-EPA Guideline Testing Chamber Location/Laboratory.
Pathogen contact time took multiple hours for an efficacy report.
The air disinfection device claims an efficacy rate of 99%. This rate is simply not sufficient when hospital-grade disinfection is needed.
Indoor air quality continues to rise in importance as a public health issue in multiple industry sectors. Many of the regulations affecting indoor air quality are only recommended guidelines by federal and nonprofit regulatory groups. These guidelines are fragmented, incomplete and overlapping, but the federal government and states are working on drafting regulations.
The EPA has strict requirements regarding EPA registered chemicals, including Good Laboratory Practices for chemistry, toxicology, and efficacy of these chemicals.
Air management devices do not require EPA registration and therefore do not require strict formal testing of their efficacy claims. Air management devices are only “regulated “ by the EPA rather than registered. Regulated devices are not required to disclose their efficacy data or verify their efficacy claims in their marketing materials.
The EPA does have a website on residential air cleaners. At this site they dispel the effectiveness claims of certain technologies such as photocatalytic oxidation. It is up to the consumer of these devices to carry out their due diligence on investigating efficacy claims in regards to particulate reduction, pathogen killing, and odor removal.
And remember, those air purification devices claiming 99% or even 99.9% reductions in pathogens are for houses, not hospitals. You can’t solve your airborne pathogen outbreak with a trip to Home Depot.
Here’s another real-life story about a hospital with an airborne pathogen crisis.
Suspected mucormycetes mold clusters at a world-renowned heart transplant facility led to the deaths of three transplant patients. These deaths resulted in the closing of the facility’s cardiothoracic intensive care unit and shut down the transplant program for nearly a week. You can imagine the catastrophe this caused for current patients, incoming patients, patients’ families, and hospital staff.
A report from the U.S. Centers for Disease Control and Prevention pointed out ventilation systems in patients’ rooms as a possible transmission vehicle for the fungal infections.
Historically, hospitals don’t regularly test for environmental airborne microbiology, with the exception of surgical suites. Staffers address surface and contact containment as much as possible. New technologies like UV-based surface eradication are certainly helping.
But for some reason, airborne pathogens are typically addressed after the fact. Thankfully, more and more advanced Infection Prevention Programs are calling for proactive measures.
The goal is to limit liability and expenditures associated with HAIs.
“With the increase in viral infection and the possibility of pandemics when large numbers of patients will have to be treated and where many others will be at risk of acquiring infections, now is the time to invest in radical new ventilation design and management strategies as well as portable air management devices.”
— Eames, I., et. al. “Airborne Transmission of Disease in Hospitals.” J Royal Society Interface. Dec. 2009. 6: p. 697-702.
You’ve heard a lot about the horrors of airborne pathogens in hospitals and bogus air disinfection claims. It’s because of this knowledge that we can now finally address how to truly decrease infection rates in hospitals.
There are two basic physical principles of ventilation in infection control:
Diluting airborne pathogens
Controlling airborne pathogen movement from one space to another
That said, you’ll need to consider numerous factors when choosing the appropriate UV air disinfection solution for your specific application and needs. These factors include:
Even though air disinfection machines don’t have to be registered, the EPA has set guidelines for the appropriate type and size of bioaerosol chamber in which to test them. Products tested under this guidelines have verifiable pathogen-killing efficacy.
Other airborne pathogen efficacy parameters that require assessment include:
An independent, third-party, nationally recognized lab facility
Test methods employed
Contact time (minutes vs. hours)
Type of pathogen
Killing percentage (ideally 99.9995%)
When analyzing and comparing these devices, it’s extremely important that testing parameters are actually directly comparable. The same conditions apply to field studies. The field studies should be conducted at unbiased facilities with scientific test conditions that eliminate all testing room variables except for the air management device itself.