Healthcare-acquired infections (HAIs) pose a significant threat to patient safety and well-being in various healthcare settings, including ambulatory care facilities. These infections, also known as nosocomial infections, are a leading cause of preventable deaths in health care environments and contribute to increased health care costs. While much attention has been given to addressing HAIs in hospitals, it is crucial to recognize that ambulatory care facilities are not immune to the risk of these infections. To effectively combat HAIs and create a safe environment for patients, health care professionals must focus on enhancing air filtration systems within ambulatory care facilities.
Ambulatory care facilities, which include outpatient clinics, surgical centers and diagnostic centers, cater to a wide range of patients who may be vulnerable to infections. Common HAIs found in hospitals, such as central-line associated bloodstream infections, Clostridium difficile infections and surgical site infections, can also occur in ambulatory care settings. Therefore, it is essential to implement robust infection control measures, including comprehensive air filtration strategies, to minimize the transmission of airborne pathogens and improve patient outcomes.
The proper filtration of air within health care facilities plays a vital role in reducing the concentration of airborne bacteria and preventing the spread of infectious diseases. Ambulatory care facilities rely on HVAC systems to provide a controlled environment for patients and staff. These systems not only regulate temperature, but also manage air quality. By implementing effective air filtration measures, health care professionals can significantly reduce the risk of airborne infections and improve the overall safety of ambulatory care facilities.
This article focuses on the importance of enhancing air filtration systems to combat HAIs in ambulatory care facilities. It explores the role of air filtration in reducing the transmission of airborne pathogens and highlights the current guidelines and standards for air filtration in health care environments. Additionally, the article discusses various enhanced filtration technologies and factors that influence filter selection. It emphasizes the significance of pre-filters and proper filter installation to maximize the efficiency and longevity of air filters. By understanding these key considerations and implementing appropriate air filtration strategies, health care professionals can create a safer environment for patients, staff and visitors in ambulatory care facilities.
AIR FILTRATION REQUIREMENTS
In ambulatory care facilities, proper air filtration design is essential to prevent the transmission of HAIs and maintain a safe environment for patients and staff. The design of air-handling units (AHUs) plays a crucial role in ensuring effective air filtration and minimizing the risk of HAIs.
ASHRAE provides guidelines and standards for air filtration in health care facilities, including ambulatory care settings. ASHRAE Standard 170-2021 outlines the ventilation requirements for different areas within ambulatory care facilities, including patient care areas, procedure rooms and surgical suites.
To meet the standards set by ASHRAE, AHUs in ambulatory care facilities must incorporate appropriate filtration systems. The recommended filter pattern for AHUs serving surgery centers typically includes a two-stage filtration approach: pre-filters and final filters.
Pre-filters are the initial line of defense in air filtration systems. They capture larger particles and contaminants, such as dust, pollen and fibers, before they reach the final filters. Pre-filters help extend the lifespan of the final filters by preventing them from clogging prematurely. The most used pre-filters in ambulatory care facilities MERV 8. These filters effectively capture particles larger than 3 micrometers in size.
Final filters, also known as high-efficiency filters, are responsible for removing smaller particles, including bacteria and viruses, from the air. In surgery centers and other critical areas, HEPA filters are recommended. HEPA filters can remove at least 99.97% of particles as small as 0.3 micrometers in size. These filters provide a superior level of filtration, ensuring a clean and safe environment for surgical procedures.
In addition to the filter pattern, the design of AHUs should consider other factors to enhance air filtration and prevent HAIs. These factors include air pressure control, dedicated infection-control systems, and minimizing unplanned airflows through building envelopes and interior spaces.
Air pressure control is crucial to maintaining the desired direction of airflow in critical areas such as operating rooms. Positive air pressure can be maintained in these spaces to prevent the entry of contaminants from adjacent areas. Negative air pressure can be employed in isolation rooms to contain airborne pathogens and prevent their spread to other areas.
Dedicated infection-control systems, such as ultraviolet germicidal irradiation (UVGI), can be integrated into AHUs to further enhance air quality. UVGI systems use ultraviolet light to deactivate and destroy microorganisms, including bacteria and viruses, as they pass through the AHU.
Minimizing unplanned airflows through building envelopes and interior spaces is important to prevent the entry of contaminants from external sources or cross-contamination between different areas within the facility. Proper sealing of ductwork, doors and windows, as well as the use of airlocks and pressure differentials, can help control and manage airflow effectively.
FILTER SELECTION
When it comes to selecting filters for HVAC systems in ambulatory care facilities, several factors come into play. Health care engineers must carefully consider these factors to strike a balance between initial cost and long-term operational costs associated with the chosen filters. By considering pressure drop, energy usage, projected filter life, ease of installation and the speed of airflow in the HVAC unit, engineers can make informed decisions about filter selection.
One of the primary considerations in filter selection is the pressure drop across the filter. Pressure drop refers to the resistance that air encounters as it passes through the filter. Filters with higher efficiency often result in a higher pressure drop. Balancing this pressure drop with the HVAC system's airflow requirements is essential to maintain proper system performance. Higher pressure drops can lead to decreased airflow, increased energy consumption, and potentially even strain on the system. Therefore, it is crucial to select filters that offer the necessary level of filtration while minimizing the associated pressure drop.
Energy usage is another crucial factor to consider when selecting filters. Filters that offer higher levels of filtration efficiency may contribute to increased energy consumption. The increased resistance to airflow caused by these filters can lead to the HVAC system working harder to maintain the desired airflow. Therefore, health care engineers should evaluate the energy efficiency of filters and assess their impact on the overall energy consumption of the system.
Projected filter life is an important consideration, as it directly affects maintenance requirements and costs. Filters have a finite lifespan before they need to be replaced. Understanding the projected filter life allows engineers to plan for regular maintenance schedules and budget for filter replacements accordingly. It is essential to select filters with a reasonable lifespan that aligns with the specific needs and operational characteristics of the ambulatory care facility.
Ease of installation is another practical consideration in filter selection. Filters should be selected based on their compatibility with the HVAC system and ease of integration. Health care engineers need to ensure that the selected filters can be installed correctly and securely within the air handling units or ductwork. Filter holding frames should provide an airtight fit to prevent air bypass and maximize filtration efficiency.
To ensure the efficacy and performance of selected filters, it is advisable to rely on testing conducted by independent third-party laboratories. These tests provide valuable insights into filter efficiency and their ability to remove contaminants effectively. Working with individuals who possess extensive knowledge of filtration, such as certified air filter (CAF) specialists designated by the National Air Filtration Association (NAFA), can help guide the filter selection process. Filter manufacturers often have CAF specialists on their teams who can provide expertise in selecting the most suitable filters for specific applications.
While it is beneficial to work closely with filter manufacturers and experts, health care engineers should also have a comprehensive understanding of the selected filters. This includes evaluating the pressure drop characteristics of the filters over their lifespan, understanding the impact on energy efficiency, and being aware of the maintenance requirements associated with each filter.
PRE-FILTERS AND FINAL FILTERS
In health care facilities, including ambulatory care facilities, the use of pre-filters is a common practice. According to the guidelines outlined in ASHRAE 170-2017, most areas of a health care facility require pre-filtration, except for a few specific areas that demand high-efficiency filters.
When designing health care facilities, it is advisable to incorporate pre-filters whenever high-efficiency filters with a MERV 13 or above are used. Pre-filters play a crucial role in capturing larger particles present in the air, thereby extending the lifespan of high-efficiency filters and preserving their integrity. By capturing larger particles, pre-filters prevent them from reaching the final filters, which are responsible for capturing smaller particles and contaminants.
The use of pre-filters offers significant cost savings in the long run. High-efficiency filters with MERV ratings of 13 and above can be considerably more expensive, costing anywhere from 10 to 40 times the price of pleated filters used as pre-filters. By capturing larger particles before they reach the high-cost final filters, pre-filters help to prolong the life of the final filters. This means that replacing pleated pre-filters on a quarterly basis is more economical than having to replace a higher-cost final filter prematurely, possibly six months earlier, due to clogging caused by large particles that could have been captured by the pre-filters.
The cost-effectiveness of pre-filters becomes apparent when considering the potential savings in filter replacements. By reducing the workload on final filters and minimizing premature clogging, health care facilities can optimize the use of high-efficiency filters and avoid unnecessary expenses associated with their frequent replacement. Additionally, the regular replacement of pleated pre-filters is a relatively cost-effective measure compared to the higher cost of replacing final filters more frequently.
The incorporation of pre-filters in health care facilities not only contributes to cost savings but also helps ensure the optimal performance of the filtration system. By capturing larger particles, pre-filters prevent these particles from accumulating on the final filters, which can impede their airflow and overall efficiency. Maintaining the integrity of the final filters is crucial for effectively capturing smaller particles and contaminants that pose a risk in health care settings.
CONCLUSION
Designing air filtration systems correctly in ambulatory care facilities is crucial for mitigating the transmission of airborne diseases. By adhering to ventilation requirements, incorporating pre-filters, and selecting appropriate filters based on factors like pressure drop and energy usage, health care engineers can optimize the performance of HVAC systems and reduce the risk of HAIs. Collaboration with filter manufacturers and experts, along with a thorough understanding of filter characteristics and maintenance requirements, is essential for successful filtration design.
Ambulatory care facilities play a vital role in providing health care services, and ensuring a safe and healthy environment is paramount. By enhancing air filtration systems, we can create an environment that prioritizes patient safety, minimizes the risk of HAIs, and promotes the well-being of both patients and health care professionals. Through continuous research, advancements in filtration technology, and adherence to best practices, we can design air filtration systems in ambulatory care facilities that contribute to a healthier and safer health care environment.
