By Tony Abate

Healthcare-acquired infections (HAIs), also called nosocomial infections, are defined as infections that patients acquire in the course of receiving healthcare. In total, according to 2015 data from the Centers for Disease Control and Prevention (CDC), on any given day about 1 in 31 hospital patients had at least one HAI; there were an estimated 687,000 HAIs in U.S. acute-care hospitals in 2015, and about 72,000 patients with HAIs died during their hospital stays.

Since the advent of the Affordable Care Act, hospitals have been held to higher accountability standards and now are required to transparently report HAIs. HAIs can not only affect a hospital’s reputation and marketability, but they can also cause Medicare reimbursements to be denied for HAI-related costs and extended stays.  

HAIs can include issues such as surgical site infections and catheter-associated urinary tract infections, but airborne infections are also a threat. Recently, the outbreak of coronavirus (2019-nCoV) in Wuhan, China, has made headlines and raised public awareness of the risk of airborne and surface infections. These may be caused by direct contact with an infected person, indirect contact such as with contaminated instruments, and inhalation of airborne droplets generated by coughing, sneezing, hospital procedures, etc. 

While droplets may be propelled only a short distance, the virus can often become suspended on particles. Tiny particles in the PM 2.5 range can stay suspended in air for long periods of time and are too small to be filtered by nasal cilia, so they are inhaled down into the lungs, allowing viruses to infect and spread. If deposited on a nonporous surface such as stainless steel, coronaviruses can remain viable for up to 7 days. This means an infected person can cough or sneeze and expel droplets into the air that ultimately deposit on surfaces. 

Anyone who contacts that surface with their hands and touches their face and can then become infected. Coronavirus 2019-nCoV can take 10 to 14 days to incubate, so an infected person may not show symptoms immediately, but researchers have identified cases where people spread the virus to others while they were still asymptomatic themselves. 

Coronavirus epidemics have occurred before. In 2003, the respiratory illness SARS infected 8,098 people and caused 774 deaths worldwide, according to the CDC. MERS (Middle Eastern respiratory syndrome) was first identified in 2012 and between that time and November 2019, there were 2,494 laboratory-confirmed cases that caused 858 deaths worldwide, according to the World Health Organization. Even worse, as of Feb. 6, 2020, there have been more than 31,000 cases of confirmed illness caused by the Wuhan coronavirus, with more than 630 deaths. (Nearly all deaths have been confined to China.) And the current outbreak is likely to grow more deadly before it improves. 

Respiratory viruses are obvious suspects, but other bacteria and viruses can be transmitted through the air as well. In one 2010 study from East Carolina University, nasal swabs were used to screen 3,638 healthcare workers for methicillin-resistant Staphylococcus areus, or MRSA. Of these, 4.3% were MRSA-positive. And of those who tested positive for MRSA, 55% were involved in direct patient care—which, interestingly, means that 45% of those who tested positive were nonclinical staff with no direct patient involvement. This suggests airborne transmission of MRSA. 


A strategy to address and improve indoor air quality (IAQ) is important to curtail the spread and impact of nosocomial infections in any healthcare facility. The U.S. Environmental Protection Agency (EPA) has defined three parameters for controlling and improving IAQ: 

  • Source control. All healthcare workers involved in patient care need to practice standard precautions to minimize the spread of pathogens as much as possible. Strategies include isolating patients with infectious illnesses, cleaning and disinfecting surfaces, as well as washing hands and using skin sanitizers and face masks as needed.
  • Ventilation. Adequate ventilation, pressurization, and air changes per hour are vital to ensure clean air moves through a less clean space and that air-cleaning strategies can work to their designed values. 
  • Air cleaning. Many good technologies exist that interact with airborne contaminants to reduce particle levels. Filtration is just one. Any filtering system must be designed to remove small range particles from the air entering the space. Ultraviolet light (UV) bulbs can also help to disinfect surfaces like air conditioning coils and other surfaces, but care must be exercised because UV exposure can be dangerous to people and can be particularly damaging to the eyes. 

Many air and surface cleaning strategies are passive and sometimes temporary. For example, wiping down of surfaces sanitizes them at that point in time but does not ensure continuous sanitization. Media filters, electronic filters, UV systems, and photocatalytic oxidation are passive technologies—they clean air that passes through the device. 

Bipolar ionization, in contrast, is an active technology; ionized air is delivered through the ventilation system to saturate the occupied space. Ions in the air interact with contaminants in the air and on surfaces to provide sanitization, a continuous disinfection effect. 

Regular IAQ monitoring is also important to ensure performance. Awareness of IAQ and air pollutant levels is increasing exponentially. They are many good IAQ monitors that use IoT capabilities to record and store data that can be accessed and used to proactively make adjustments to improve air quality. Cutting-edge air purification systems also used real-time IAQ data to adjust air purification output on a proactive and reactive basis. 

What you can’t see in the air can hurt you. However, by identifying areas for concern, developing a proactive strategy to address airborne transmission of contaminants, and measuring results, a hospital or other care facility can reduce its exposure to nosocomial infections and their adverse health effects and treatment costs. 

Tony Abate is vice president and chief technical officer at AtmosAir Solutions in Fairfield, Conn., and a certified indoor environmentalist. Questions and comments can be directed to 24×7 Magazine chief editor Keri Forsythe-Stephens at [email protected].