How to Improve Indoor Air Quality in Hospitals

Indoor air quality (IAQ) control is crucial for infection prevention in hospitals.

Airborne pathogens are a major cause of health care-associated infections (HAIs). Studies show that hospital air quality control is just as important as managing surface disinfection and human contact for a safe hospital environment. 

Decreasing infection rates in hospitals starts with recognizing the serious threat of airborne pathogens and implementing an effective pathogen reduction solution.

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1.  What Are Airborne Pathogens?

Portrait of a surgeon wearing a surgical mask in a hospital

Airborne pathogens: pathogens in the air that are spread on solid particles or droplets.

Solid particles may come from human skin scales or flakes.

Respiratory droplets can be spread via coughing, sneezing, or otherwise coming into contact with infectious droplets.

These small respiratory droplets start to evaporate after release and then shrink, resulting in droplet nuclei that can remain suspended in the air (and infectious) for long periods of time.

Artificial means of producing potentially infectious aerosols in hospitals include using respiratory assist equipment such as:

  • Nebulizers
  • Ventilators
  • Oxygen masks
Concept showing doctors stethoscope and a clock face simulating an appointment

How Long Do Airborne Pathogens Remain Infectious?

Airborne pathogen survival depends on the amount of time they remain in the air as well as ambient environmental factors, like temperature and humidity. Spread 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. Differences in individuals' receptors in the upper and lower respiratory tracts affects how easily inhaled airborne pathogens cause infection and disease.

Human respiratory activity can also cause changes to the pathogen while it's inside the body. So, the body may expel a different variety of pathogen than it took in, 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
  • Staph
  • Strep

Sneezing or speech is more likely to expel pathogens inhabiting the upper respiratory tract, which leads to comparatively mild conditions like the common cold.

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2.  How Is Airborne Disease Transmitted In Hospitals?

We expel pathogens into the air via different bodily fluids, organs and functions:

  • Upper and lower respiratory tract
  • Mouth
  • Nose
  • Human skin scales
  • Vomiting
  • Diarrhea
  • Breathing
  • Coughing
  • Sneezing
Dripping water taps and other contaminated water sources can also transmit infection.

One in 25 hospitalized patients are affected by a health care-associated infection, according to the U.S. Centers for Disease Control and Prevention (CDC).

Patients picked up 721,800 HAIs at U.S. acute care hospitals in 2011. Of those infected, about 75,000 died, according to the CDC.

Common Airborne Pathogens Found in Hospitals

a.  Mold

Recently, there were reports of deaths caused by mold clusters at two Pennsylvania hospitals. Investigation showed heavy mold growth on the hospital linens being used.

Unsurprisingly, this is one of the cases that has fueled concerns about airborne HAIs. Other infamous cases frequently involve Aspergillus mold spores.

b.  Legionnaires’ Disease

Awareness of healthcare-associated infections increased after a Legionnaires’ outbreak killed 12 people in the South Bronx.

Legionnaires' disease doesn't spread from person to person. Instead, the bacteria spreads through mist, such as from air-conditioning units for large buildings.

c.  Tuberculosis

Health care workers infected with TB can spread infection widely. Despite extensive screening of patients and staff, there are still reported cases of TB infections in hospitals.

d.  Norovirus

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.

e.  MRSA

MRSA can survive on skin scales for up to 80 days, and spores of Clostridium difficile may last even longer.

On smaller skin scales, MRSA can travel in the air for the full length of a ward. Even minimal colonization of these bacteria in open wounds and mucous membranes can cause life-threatening infections.

3.  How Can Hospitals Reduce (& Prevent) Airborne Infections?

Historically, hospitals haven't regularly tested for environmental airborne microbiology, with the exception of surgical suites. Airborne pathogens are typically addressed after a crisis that causes sickness and, in many cases, death.

Thankfully, more advanced Infection Prevention Programs are calling for proactive measures.

The goal of Infection Prevention Programs 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.

a.  Hospital Air Ventilation Maintenance

Air conditioning units in a row

Common Biogenic & Environmental Contaminants Found in Ventilation Systems

  • Pollen
  • Mites
  • Protozoans
  • Airborne cystic spores
  • Viruses
  • Bacteria
  • Fungi (including mold)

Innocuous, ever-present necessities like HVAC systems can play a huge role in spreading HAIs. Improper ventilation, aging equipment, and water damage are all threats to breeding biogenic and environmental contaminants.

Impact of Poorly Maintained Ventilation

There are two basic physical principles of ventilation in infection control:

  1. Diluting airborne pathogens
  2. Controlling airborne pathogen movement from one space to another

In communal areas (such as waiting areas, cafeterias, corridors, and stairwells), ventilation should provide a steady exchange of clean air for potentially contaminated air. 

Clogged filters, leaking ducts, or even contaminated ducts may lead to a buildup of the infectious agents they were designed to remove. Poorly maintained or worn-out ventilation systems can act as a source of airborne infections rather than a defense against them.

Improving Ventilation Systems & Maintenance

Ventilation systems must be carefully designed to remove airborne contamination as soon as possible.

Filtration systems must have their integrity regularly checked.

Laser particle counters and microbial samplers can provide continuous monitoring of ventilation performance.

Maintenance staff MUST frequently maintain your hospital’s ventilation system to sustain the required safe air change rate.

b.  Access to Face Masks for Patients & Staff

With patients and staff in close proximity, personal means of protection can be effective, like masks or portable air management devices. As a standard, wearing a face mask is good practice to prevent transmission of illnesses.

That said, there are many complex issues surrounding masks Even though materials, methods, and mask design have improved over the years, effectiveness may vary against viral- and bacterial-sized particles.

Other studies have shown the actual act of wearing masks and keeping them on in a proper position is very difficult. Sick patients may have difficulty maintaining proper and consistent mask use -- or may be disinterested in doing so -- to contain their infection and protect others.

c.  UV-C Air Disinfection Machines

Proactive health care facility managers want to identify and address potential issues before they become a crisis. This is now possible with portable air disinfection machines - specifically, UV-C air disinfection devices like SAM 400.

SAM was tested in full EPA compliance, with an unparalleled standard for air disinfection. A single SAM device eliminates 99.9995% of introduced viral pathogens, guaranteeing a near-sterile room under actual industry health care conditions.

While exact results may differ between devices, SAM provides complete disinfection of a standard 800-sq.-ft. room in minutes, and whole-room air exchange after only 20 minutes. No ozone production, no external UV-C exposure, and no VOCs or odors remaining.

Major U.S. hospitals report 99.97% reductions in air particulate matter with SAM, independent of interference from existing HVAC systems.


4.  Choosing the Right Air Disinfection Device for Your Hospital

medical pills industry  factory and production indoor-1

a.  Factors to Consider When Comparing Air Disinfection Machines

  • Functionality
  • Portability
  • Design
  • Weight
  • Pathogen killing
  • Odor removal
  • Air flow rates
  • Air inflow/outflow sites
  • Safe use
  • Noise level
  • Independent, third-party, nationally recognized labs verifying efficacy claims
  • Absence of dangerous byproducts

b.  Third-Party Verification of Efficacy Claims

Because air management devices do not need to be registered with the EPA, they are not required to disclose their efficacy data or verify their efficacy claims in their marketing materials.

However, though they don’t have to be registered, the EPA does have 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.

An independent, third-party, nationally recognized lab facility should perform this testing and report:

  • Test methods employed
  • Contact time (minutes vs. hours)
  • Type of pathogen
  • Killing percentage (minimum 99.9995%)

The same conditions apply to field studies. 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.

When analyzing and comparing air disinfection solutions, it’s extremely important that to compare directly comparable testing parameters. Otherwise, it's easy to invest in a solution that doesn't truly eliminate airborne pathogens. 

c.  Signs of Unqualified Efficacy Testing

The following signify that testing did NOT meet EPA guidelines (10x10x8 ft.) to be considered an effective air disinfection device.

  1. The device was tested in small bioaerosol chambers. Testing occurred in a very small test chamber or non-full-size room, which can skew efficacy results.
  2. The device was tested in non-independent academic labs. Testing happened in a non-EPA Guideline Testing Chamber Location/Laboratory. This means the EPA cannot guarantee the quality of testing procedures.
  3. The device was tested with excessively long contact times. If pathogen contact time took multiple hours for an efficacy report, it's less likely that it was caused by the device.
  4. The device had an ineffective killing percentage rate. If the device claims an efficacy rate of less than 99.9%, its killing rate is insufficient for hospital-grade disinfection.

d.  Avoid Photocatalytic Devices That Produce Ozone

The EPA has dispelled effectiveness claims made by air disinfection devices that involve photocatalytic oxidation and ozone production.

Hospitals should be wary of these devices because health care facilities are NOT permitted to produce additional ozone.

A hurdle for those in charge of hospital infection control is navigating airborne pathogen products marketed with claims of efficacy using photocatalytic oxidation, aka ozone production. (In fact, some “disinfection” units flat out produce ozone.)

Because of the FDA and EPA reports dispelling these efficacy claims, some older companies whose products produce ozone have changed their descriptions to “photocatalytic ionization” instead of “ozone production.”

e.  Residential vs. Hospital-Quality Air Management Devices

Most air purification devices reduce particulates, not pathogens, and are used typically in houses, not hospitals. Residential areas are not nearly as large or as dangerous as a hospital environment.

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.

5.  How One Hospital Successfully Eliminated Airborne Pathogens After a Crisis

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.

The hospital followed these steps to prevent further infections:

  1. Used safe cleaning solutions to destroy bacteria, viruses, and spores
  2. Deployed a robot that uses ultraviolet light to disinfect medical equipment as well as hospital and operating rooms
  3. Also used the robot to target at-risk areas with thermal imaging

The hospital system also hired experts to assess its facilities where remodeling projects may have caused dust- or construction-related risks.

For lower-immunity patients, such as in cancer treatment areas, even low levels of microorganisms can cause increased risk. These are certainly areas where basic or fundamental air quality treatment is required.

Other strategies for infection control include:

  • Administrative controls
  • Engineering controls
  • Hand washing
  • Masks
  • Reduced physical contact
  • Removal of jewelry

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