The Delhi High Court on Thursday told the authorities to treat as representation, a petition highlighting the role played by improper dilution and ventilation in airborne infection in built spaces.

The Division Bench comprising Chief Justice D.N. Patel and Justice Jyoti Singh passed the direction on a plea emphasising the need to put on preventive methodologies in the in-built environment, so as to make these spaces immune to the spread of infection.

Advocate K.C. Mittal, representing the petitioner, submitted that in closed buildings, the Covid-19 virus spreads rapidly and centralised air-conditioning further aggravates the issue.

The Bench was of the view that the grievance of the petitioner relates to taking proper and appropriate measures in closed areas to reduce the presence of biological contaminants in the air; and the same requires observations and suggestions by an expert body.

The Bench orally remarked that an expert team was also called in the High Court for inspection of the Delhi High Court Complex and on the suggestions of the said body, necessary changes were made in the building.

The Bench disposed of the petition, while directing the concerned authorities to treat the petition as representation and decide it in accordance with law, rules, regulations and government policies applicable to the facts of the case, as expeditiously as possible, keeping in mind the present situation.

The petition was filed by one Raja Singh, a research scholar working in the area of airborne infection spread and the role played by ventilation in containing the spread, through Advocates Yugansh Mittal and Amit Prakash Shahi.

The plea sought directions for appropriate measures, enabling proper dilution and ventilation of air in built environments, keeping in view the presence of biological contaminants in air.

The petitioner claimed that during his research work, he came to know about the worsening quality of air due to biological contaminants and improper dilution and ventilation of air in built spaces such as houses and offices as also transportation means, such as air-conditioned buses, trains and other modes of transport.

The petition highlighted that an application was filed before the Delhi High Court in April, 2020, raising concern about the usage of central air-conditioning in the High Court Complex in the light of Covid-19 pandemic.

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Since there was no conclusive evidence at that time, on the spread of virus through air, the Bench of Chief Justice D.N. Patel and Justice C. Hari Shankar, vide order dated May 1, 2020,disposed of the application on the ground that no mathematical solution to the problem of air contamination is possible, while observing that a Special Committee has already been constituted to look into the issue. But later on in July, 2020, the World Health Organisation stated in a report that COVID-19 also spreads through the airborne route.

The petitioner filed several applications before the concerned authorities highlighting the issue, however, no concrete response has been received yet.
The plea states: “The scientists have warned about a future pandemic which would be more disastrous and destructive than the Covid-19 and will spray through air. The dilution ventilation diffuses the concentration of the droplets as such minimizing the probability of infection. It is stated that the dilution of air is easiest in the open air and becomes an issue requiring intervention in the indoor spaces.”

The chances of contracting the infection are high in enclosed areas and poorly ventilated spaces. Trapping and killing the virus through pressurisation and filtration are effective in destroying it.

By Dr KK Aggarwal

Person to person transmission is a well established route for the spread of Covid-19. And it’s not just symptomatic persons, even asymptomatic and pre-symptomatic people can spread the virus to others. This spread occurs via respiratory droplets carrying the virus and which are produced during exhalation (eg, breathing, talking, singing, coughing or sneezing) and when a person is in close contact (within six feet) of a person with Covid-19. Transmission may also occur through contaminated surfaces, but it is a less common route for the spread of the virus.

Airborne transmission of the Covid-19 virus has been a subject of debate and cannot be ruled out with certainty. The latest Scientific Brief, dated October 5, 2020, from the Centers for Disease Control and Prevention in the US, has acknowledged this mode of spread and says that “pathogens that are mainly transmitted through close contact (i.e., contact transmission and droplet transmission) can sometimes also be spread via airborne transmission under special circumstances”. The smaller droplets and particles (<5µ) containing the virus remain suspended for long hours and are consequently transported to long distances (usually greater than six feet). The size of the virus is 80-160 nm and it remains active for 48-72 hours on indoor surfaces. This is where the challenge lies as the virus becomes airborne and is carried into rooms in air conditioned buildings.

The chances of contracting the infection through airborne transmission are particularly high in enclosed spaces (buildings, public transport) and/or poorly ventilated spaces or when there is prolonged exposure to respiratory droplets produced during shouting, loud singing and exercising. There are two main transmission mediums in indoor spaces: cough generated aerosols and particulates (dust) suspended in air. Reduction of indoor aerosols and dust levels is a step towards mitigation of this source of transmission.

Several outbreaks in confined spaces such as shopping malls, worker dormitories, religious meetings and cruise ships have been reported. The Diamond Princess cruise ship outbreak, reported on February 1 as a passenger who had disembarked in Hong Kong tested positive, led to the ship being quarantined immediately in Japanese waters. This is a classic example of how closed spaces facilitate the spread of the virus. A study of the air conditioning system on the ship revealed traces of the Covid-19 virus on a variety of surfaces in cabins of both symptomatic and asymptomatic passengers up to 17 days after the cabins were vacated. It also highlights the role of poor ventilation systems in the spread of Covid-19.

Some air-conditioning systems recirculate indoor air and mix it with some fresh outside air. The air current produced by AC fans allows the virus to stay suspended in the air for a longer time and travel further than they might otherwise go. As the ship used a centralised AC and the onboard ventilation system was not designed to filter out particles as small as the coronavirus, the disease spread rapidly to other cabins during the quarantine period.

However, the same cannot be said of the air-conditioning system inside planes. According to the International Air Transport Association, the risk of transmission in planes is probably lower than in many confined spaces because modern airplanes have cabin air filtration systems equipped with HEPA filters. HEPA or high efficiency particulate air filters have similar performance to those used to keep the air clean in hospital operating rooms and industrial clean rooms. These filters are very effective at trapping microscopic particles as small as bacteria and viruses and can capture greater than 99 percent of airborne microbes in the filtered air. The cabin air system is designed to operate most efficiently by delivering approximately 50 percent outside air and 50 percent filtered, re-circulated air. This normally provides between 15 and 20 cubic feet of total air supply per minute per person in economy class. The total air supply is essentially sterile and particle free. Cabin air circulation is continuous. Total airflow to the cabin is supplied at a bulk flow rate equivalent to 20 to 30 air changes per hour.

Technological methods recommended to reduce airborne transmission of the virus are dilution, pressurisation, filtration and purification (destroying infectious agents in air). Filters trap all pathogens, forming a colony of pathogens and are a source of infection. “Trap and kill” is desirable. Hence, purification is needed.

ASHRAE or the American Society of Heating, Refrigerating and Air-Conditioning Engineers recommends seven strategies: dilution (high ventilation rates i.e. air changes per hour), airflow patterns (how the air is flowing), pressurisation (negative pressure in isolation rooms with respect to surroundings), temperature, relative humidity, filtration and ultraviolet germicidal irradiation as strategies to reduce exposure to infectious aerosols.

The way to reduce this transmission, therefore, is to improve ventilation with outside air. This can be done through natural means or fresh air. So open the windows if possible. Else use mechanical ventilation systems. Avoid recirculation of air or achieve more fresh air (greater than 50 percent). The air conditioning and ventilation systems (air filters) for residential as well as other buildings such as hospitals, hotels and schools should be regularly inspected and cleaned to prevent transmission.

Buildings that use central ventilation should use the most efficient filters. Higher efficiency filters like HEPA should be used and higher air change rates per hour (10-15) are advisable for mechanically ventilated buildings. Use a window air conditioner that has an outdoor air intake or vent; keep the vent open.

When air conditioning or ventilation is not available, as is the case in most homes, open the windows to allow fresh air into closed spaces; alternatively, an air purifier can be used. All exhaust fans should be functional; they should be kept operating when the building is occupied. Fans should generally be avoided in closed spaces with a large number of occupants. ISHRAE (Indian Society of Heating, Refrigerating & Air Conditioning Engineers) recommends: “Fans should be operated with windows kept partly open. If an exhaust fan is located at a nearby location then it must be kept running to exhaust air for better ventilation”.

The Covid-19 virus is known to remain viable for up to four hours on copper, 24 hours on cardboard and 2-3 days on plastic or stainless steel. All environmental surfaces should be regularly cleaned and disinfected to eliminate the virus. The ideal temperature and relative humidity range is below 30 degrees Celsius and above 80 percent, respectively. This is not a comfortable situation. The room temperature should be set between 24 and 30 degrees Celsius and RH between 40 and 70 percent, according to ISHRAE. In dry climates, the RH should not be allowed to fall below 40 percent. Recirculation of indoor air in closed spaces for longer duration (as in offices, trains, ships) can transmit the infection despite the recommended physical distancing. “Good” ventilation and not just ventilation, therefore, is of paramount importance to decrease the risk of indoor infection.

But, improving ventilation alone will not protect one from Covid-19.  It is just one of the protective measures. Others include physical distancing (at least one metre), avoiding crowded public places, correct and consistent use of face masks (three layered) and meticulous hand hygiene. Such stringent measures can work as a deterrent.

—The writer is President, Confederation of Medical Associations in Asia and Oceania, and former National President, IMA

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The need of the hour during the Covid-19 pandemic is a medical oxygen plant that can replace oxygen cylinders. This will avert India’s oxygen shortage crisis and help those with lung problems

By Dr KK Aggarwal

Covid-19 is here to stay. Even as it subsumes all countries, its insidious way of entering the body has set alarm bells ringing. However, new forms of supplying oxygen to patients have given a ray of hope.

One of the fallouts of the virus is silent hypoxia or walking dead—a condition where the person develops low blood oxygen levels but is conscious and has no confusion or altered consciousness. This silent hypoxia, if not treated in time, can end in cellular and organ hypoxia, leading to multi-organ failure. In some cases, hypoxia is associated with inflammation of the body, leading to a hyper-immune inflammatory condition. In others, it leads to clots in all the smaller and larger vessels of the body. In a few patients, it develops a massive cytokine storm, leading to pulmonary and multi-system failure at the same time. But some 80 percent of Covid-19 patients require no treatment and become alright just by simple observation.

Timely detection of silent ischaemia can save lives. Starting oxygen early, giving low molecular weight heparin, a blood thinner, and giving early antiviral drugs at the time of detecting low oxygen levels can save lives. It would be a good idea for every family to buy an oxygen monitor to detect early fall of oxygen, defined as a limit lower than 92. It is believed that India has the lowest Covid-19 mortality in the world and that is due to the early detection of silent hypoxia.

But the 15 percent who get affected, require timely oxygen and only 5 percent of them require ventilation. Out of these, 15 percent can be treated with simple oxygen. In young and healthy patients, oxygen treatment can be started at home or in smaller hospitals through oxygen cylinders or making oxygen available at home.

Portable oxygen concentrators is one option and another is a medical oxygen plant. Absstem, a company supplying oxygen generators, can replace oxygen cylinders with a self-generating oxygen plant. This is a revolutionary measure to avert India’s oxygen shortage crisis during Covid times and will go a long way in reshaping our healthcare industry.

This can give hospitals continuous, affordable and contactless supply of oxygen. Earlier, oxygen cylinders or liquid oxygen were used, which is expensive, time-consuming and requires physical contact. The medical oxygen generator uses electricity to produce oxygen from atmospheric air for the entire hospital. But an oxygen concentrator is a device that concentrates the oxygen from a gas supply (typically ambient air) by selectively removing nitrogen to supply an oxygen-enriched gas.

Most medical oxygen generators work on the principle of pressure swing adsorption, widely termed as PSA. This conventional gas separation technology is being used to separate oxygen from compressed air. The major components are a pair of adsorbent vessels, surge tank, switching valves, intelligent PLC, oxygen analyser and instruments. The adsorbent vessels, filled with Zeolite (crystalline structures made of silicon, aluminium and oxygen) adsorb nitrogen and carbon dioxide, whereas oxygen is not adsorbed due to its larger molecular size and passes through the adsorber to the surge tank.

Early oxygen therapy can save lives and serious patients may require oxygen for days together. Imagine a situation where a large number of people require oxygen and hospitals are overloaded. This is what happened in Italy. There were not enough oxygen cylinders for patients to have oxygen therapy at home or in the hospital.

It would be a good idea during the pandemic for everyone to buy an oxygen monitor. Every family should have an oxygen generator or concentrator which can give oxygen supply of at least five litres per minute at home and 10 litres per minute in hospital settings. All hospitals must have, apart from a central oxygen supply unit, an oxygen generation machine. In the long run, these plants will be cheaper, cost-effective and reduce the cost of treatment. With modern oxygen generators, entire hospitals can run on their supply.

Some patients require long-term oxygen therapy. The indications for this are chronic lung disease, including a pulse oxygen saturation (SpO2) less than or equal to 88 percent. Many patients can be cured by using oxygen concentrators and prone positioning. In two recent studies, self-proning was associated with improved oxygenation parameters in at least two-thirds of adults with Covid-19.

Even hospitalised patients with Covid-19 should spend as much time as is feasible and safe in the prone position while receiving oxygen or non-invasive modalities of support such as high-flow oxygen delivered via a nasal cannulae or non-invasive ventilation. The WHO suggests titrating oxygen to SpO2 greater than 90 percent. For most critically-ill patients, targeting an SpO2 between 90-96 is feasible. Higher flows of oxygen may be administered using a simple face mask, venturi face mask or non-rebreather mask, but as the flow increases, the risk of dispersion also increases, increasing contamination of surrounding environment and staff. All these situations can be handled by portable oxygen concentrators (POCs) or oxygen generators in hospitals.

Portable generators make use of improved battery technology and the size and power of pumps and motors provide lightweight, battery-powered oxygen concentration. POCs are smaller than oxygen concentrators designed for home use and are battery operated instead of being continuously plugged into an electrical socket. Battery lives range from 2.5 to 8 hours. Additional batteries can extend the time that a patient can de­pend on it for oxygen supply. POCs vary in oxygen flow.

The weight and size of oxygen concentrators is partly determined by the flow requirement of the patient. While a standard oxygen concentrator weighs 16 to 23 kg, several POCs have been developed that weigh between 2.3 and 8.2 kg. As they generally deliver oxygen via pulsing, there could be a lack of delivery during sleep if the patient resorts to mouth breathing and does not trigger the pulse.

Using an oxygen-conserving device in conjunction with the concentrator enables adequate oxygen delivery at lower flows. Most POCs have an integrated conserver, which may not be ideal for patients who require a higher flow rate. However, some larger units provide continuous oxygen delivery options. Investing in such devices may help save a stitch in time.

—The writer is President, Confederation of Medical Associations in Asia and Oceania, and former National President, IMA