Second Wave of Corona Pandemic 2021: COVID-19 Indoor Safety Guidelines
By: Saad A Khan, Ph.D.
Tags: Coronavirus, Health, Mental Health, Covid 19, Safety

Consider Exposure of time, Number of people and Type of space (ENT) next time when you are indoor. This abbreviation is proposed based on the work of Bazant 2020:

Exposure time and personal distance both are important parameters and directly linked to risk of infection transmission: (exposure time is referred to the amount of seconds/minutes/hours which a person comes in contact with another person)

Standing 6 feet apart is safe for a few seconds , but maybe not for a few hours

, but maybe not for a few hours Any person within 6 feet for more than 15 minutes is considered as close contact

is considered as 6 feet distance may protect us from large droplets when person coughs, but the micro droplets can remain airborne (suspended in the air) and mix in air. Fomite transmission (material/objects) from surface cannot be over ruled and disinfecting surfaces is important.

(suspended in the air) and mix in air. Fomite transmission (material/objects) from surface cannot be over ruled and is important. Social distance, low exposure time, good ventilation and wearing facemasks together can reduce the risk of infection transmission

Number of people in room, activity and quality of space is an important parameters:

The number of people in a room and the type of space can determine the level of risk of infection transmission. Poor quality of space (closed windows, low height of roof, smaller length and wider of room, poor recirculation and quality of air)

and the type of space can determine the level of risk of infection transmission. Poor quality of space (closed windows, low height of roof, smaller length and wider of room, poor recirculation and quality of air) Less number of people , with light breathing talking normal/whispering, with well fitted masks in a bigger and ventilated rooms are at less risk of acquiring corona virus compared to larger number of people, with heavy breathing and talking loudly/singing, with no mask in poorly ventilated rooms.

larger number of people, with heavy breathing and talking loudly/singing, with no mask in poorly ventilated rooms. Type of activity and direction of person facing your face is important. At any distance, remaining quiet and calm is safer than singing or exercising. Sitting adjacent to a person is safer than sitting facing the person due to the throw of micro droplets during talking.

than singing or exercising. Sitting adjacent to a person is safer than sitting facing the person due to the throw of micro droplets during talking. Elderly (above age 60), people who have gone through medical treatments and are considered immunocompromised (cancer treated) , people with previous history of asthma (weak lungs) and other systemic diseases (uncontrolled diabetes, cardiac surgeries etc) are more susceptible than others.

(above age 60), people who have gone through medical treatments and are considered (cancer treated) , people with previous history of (weak lungs) and other (uncontrolled diabetes, cardiac surgeries etc) are more susceptible than others. Children can be the silent agents in spreading corona virus without showing symptoms. All precautions are applied on them just as it is applied on adults.

Type of space (room size, ventilation, kind of interaction)/ room specifications and personal distance are important parameters:

Total floor area, average ceiling height, ventilation system, recirculation of air and relative humidity are key parameter to assess the risk of a transmission within a given specification of a room

to assess the risk of a transmission within a given specification of a room 6 feet of separation is safer in a ventilated hospital than inside a sealed tent

hospital than inside a sealed tent 25 people are safer in a large gymnasium than in a crowded restaurants

than in a crowded restaurants poorly ventilated indoor air, distance less than 6 feet, constant influx of new people, staying in close contact for more than 15 minutes combined increases the risk of infections

the risk of infections maintaining moderate temperature at home during winters is a big safety. Dryness, humidity and cold air must be controlled inside homes. This will reduce the chances of infection transmission

Taking the above precautions at personal and at organizational level will reduce the risk of infection transmission.

Limiting gathering, reducing extended time of leisure interaction and encouraging staff to work from home whenever possible

Allow entry of non-essential people in your building; delay the elective work

For more precautions add air filters and disinfecting surfaces

Although the contact time is extremely low in elevators but it has poor ventilation, if possible use stairs in the building

Use of personal protective equipment (PPE) which provides adequate protection. There are many poor quality of masks and disinfectants in the market which are not considered adequately effective

Traditional infection control pyramid adapted from the US Centers for Disease Control

If you are looking for more information to reduce infection transmission in your office, check CDC website.

Conclusion: To reduce the spread of SARS-CoV-2, the new public health guidelines are recommended to have limits on: person-to-person distance (6 feet / 2 meters), contact time (15 minutes), number of people in moderate size halls (25 people), and quality of ventilation (6 air changes per hour).

*please note these precautions are most urgent and appropriate in the view that viruses mutates and their virulence (strength) increases with time, vaccines will take longer till everyone gets it. Precaution is better than cure!

References:

Lidia Morawska et al. How can airborne transmission of COVID-19 indoors be minimised? Environment International. Volume 142: 2020.