Indoor Air Quality (IAQ) is essential in any building or facility management area as it is one of the key factors that decide the nature or quality of air affecting the health and well-being of building occupants. Poor indoor air quality can aggravate respiratory diseases. If the air inside a room is not cooled or heated as per the occupant’s preference, they may experience thermal discomfort.
Importance of IAQ in Hospitals
Healthcare facilities or hospitals are meant to provide maximum care in a clean and pathogen-free environment with controlled temperature, humidity and extremely efficient air filtration. Moreover, the maintenance of proper IAQ in hospitals helps to prevent recovering patients from acquiring secondary infections. It also expedites the recovery of patients. IAQ becomes an important aspect in hospital facilities because generally the patients who are admitted have low immunity and lack of proper indoor conditions can aggravate their illness. IAQ of a healthcare facility includes multiple parameters such as temperature, relative humidity, CO2 level, lighting conditions, contaminants etc. Be it the general ward, ICUs, nursing homes or any other kind of facility, pristine indoor air quality is a must.
Vikram Murthy, Former President of Indian Society of Heating, Refrigerating and Air Conditioning Engineers (ISHRAE) and Director, Univac Environment Systems informs, “In many general hospitals across India, where conditioned air cooling is not provided, simple forced or natural ventilation may be applied and good hygiene practices are followed. However, this may bring in outdoor contaminants, heat and humidity that can make indoor environment uncomfortable if the outdoor climate is not mild and clean. In such hospitals patients must be kept in shaded areas which are surrounded by trees.”
Some hospitals are centrally air-conditioned, while some have unitary air conditioners that re-circulate air that is cooled and dehumidified. “The quality of this air determines the comfort and well-being of patients and care givers, as well as ensuring the safety of recovering patients from acquiring secondary infection,” adds Murthy.
Emphasising ventilation and air conditioning systems for ensuring proper IAQ, Vimal Chavda, National Head – HVAC, Testo India, states, “They help in maintaining proper air circulation, humidity and removing dust and other airborne substances.”
Testo India has a range of products like Testo 160 wireless LAN data logger that measures, monitors and documents temperature, humidity, light intensity, UV radiation and CO2
concentration in all rooms and sections of the hospitals – automatically and without interruption, covering all indoor climate monitoring parameters in one.
Chavda informs that products like Testo 440 and Testo 400 for intuitive air velocity and IEQ measurement can carry out measuring tasks on air conditioning and ventilation systems
reliably under control with just one versatile instrument and multiple ranges of wired and Bluetooth probes.
ANSI/ASHRAE/ASHE Standard 170-2008, states that ventilation represents a primary infectious disease controlstrategy through dilution of room air around a source and removal of infectious agents. Directed supply or exhaust ventilation, such as non-aspirating diffusers for unidirectional low-velocity airflow, is important in several settings, including operating rooms.
Murthy says that IAQ must ensure the following:
• Prescribed temperature and humidity depending on the nature of treatment and special application within the hospital.
• Trap dust and prevent transmission of pathogens by good hygiene practices, fumigation, prescribed filtration and other methods including UV disinfection.
• Continue supply of ventilated air that is free from carbon dioxide beyond prescribed limits and all other contaminants including odours.
• Ensure no cross-contamination occurs between infected patients and others.
• Monitor and adjust indoor climate conditions depending on outdoor climate to maintain minimum thermal shock for patients.
Role of HVAC in Fighting Spread of Coronavirus
The entire world has been facing a tough time since the outbreak of the novel coronavirus disease called COVID-19 since its first occurrence in December 2019 in China. The World Health Organisation (WHO) declared it as a pandemic on January 30. Millions of people across the globe have been tested positive for COVID-19 and many thousands have lost their lives. And this count is increasing.
American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), an organisation devoted to the advancement of indoor-environment-control technology in the heating, ventilation and air conditioning (HVAC) industry, has issued guidelines for addressing COVID-19 concerns regarding the operation and maintenance of heating, ventilation and air-conditioning (HVAC) systems.
“The recent escalation in the spread of coronavirus disease 2019 is alarming on a global scale,” said 2019-20 ASHRAE President Darryl K Boyce in a release.
EUROVENT, European Industry Association for HVACR, highlights in a release that proper ventilation, with a higher degree of fresh air supply and air exchange, the use of the correct filter types and careful maintenance can be important factors in the containment of the coronavirus outbreak.
It is observed that the virus escalates infections mainly through contact, droplet, and airborne transmission. In order to control the spread of unwanted bacteria or viruses in the air, COVID-19 positive patients are kept in special isolation rooms in hospitals. Murthy suggests maintaining higher indoor air temperature around 30 Degree Celsius, higher humidity above 60 per cent and good ventilation of 25 per cent outdoor air for hospitals where COVID-19 positive patients are admitted, especially within isolation wards. “Heat recovery equipment that has cross-contamination between supply and returns airstreams must not be operated,” he adds.
Elaborating further, Murthy states, “The exhaust from such isolation ward spaces must be released after being filtered through regularly replaced absolute filters and the exhaust must be treated with hot dry air above 60 Degree Celsius to kill any remaining microbes. This exhaust air must be released outdoors away from human presence and any hospital air intakes.”
“In these rooms, a negative pressure has to be maintained and the airflow, as well as the pressure in the room, has to be checked and if possible logged regularly. In the facilities where HVAC equipment are installed, the cleaning of the ducts, removal of moisture from heat exchangers, which can be monitored using humidity and temperature of the coils is very important,” informs Chavda from Testo India. He further notes that HVAC equipment should have a well-maintained filtration system and the filters should be regularly checked in order to avoid any kind of bacteria, virus or any particle from passing through.
As a precautionary measure, he says that at the same time the right airflow and its direction has to be checked and the air exchange rate in ICUs, quarantine areas and other zones has to be maintained.
Airborne substances containing bacteria from cooling towers, evaporative condensers or humidification sections of the air handling units of air-conditioning systems can contaminate the indoor conditions of the facility. Chavda observes, “Operation and maintenance of HVAC systems using proper instruments, in hospitals become paramount. Logging the data, generation and maintaining the records become very easy with Testo measuring instruments so that whenever the authorities need to check for the maintenance it is available in the form of a non-editable PDF report.”
ASHRAE maintains that because small particles remain airborne for some period of time, the design and operation of HVAC systems that move air can affect disease transmission in several ways. These include supplying clean air to susceptible occupants; containing contaminated air and/or exhausting it to the outdoors; diluting the air in a space with cleaner air from outdoors and/or by filtering the air; cleaning the air within the room.
On the other hand, Murthy opines that the present research and findings have not provided clear evidence of the prescribed path to help prevent the spread of COVID-19 virus by application of HVAC equipment. The detailed pathological nature of the virus, its airborne nature as well as its detailed properties of adherence to bodies and surfaces are under study by scientists at laboratories around the world.
“At present, it is reasonably known that the COVID-19 virus is microscopic – so it cannot be trapped even by absolute filters unless it is aerolised into droplets or moisture or the virus adheres to indoor dust and is then trapped inside such filters,” adds Murthy. He further recommends that regular replacement of filters is necessary for AHUs supplying a
COVID-19 isolation ward.
ASHRAE recommends the strategies of interest to address disease transmission: dilution ventilation, laminar and other in-room flow regimes, differential room pressurisation, personalised ventilation, source capture ventilation, filtration (central or unitary), and UVGI (upper room, in-room, and in the airstream).