MAY 28 — The World Health Organisation and the United States’ Centres for Disease Control (CDC) and Prevention have accepted that the coronavirus can spread through the air (airborne). The virus can spread in poorly ventilated and/or crowded indoor settings, where people tend to spend longer periods of time. Airborne transmission refers to the presence of microbes within droplet nuclei, which are generally considered to be particles less than 5 micron in diameter. They can linger in the air for sustained periods of time and be transmitted to others over distances greater than 1 metre. The virus multiplies in the respiratory tract, enabling it to spread in particles of varying sizes emitted from an infected person’s nose and throat during breathing, speaking, singing, coughing and sneezing.

We often associate pollution with big factories pumping out smelly clouds or old cars puffing out smoke through their exhaust.  However, indoor air pollutants can be more dangerous than outdoor air pollution. The common indoor pollutants are carbon monoxide, biological agents (bacteria, viruses, mould and fungi), nitrogen dioxide, secondhand smoke, (environmental tobacco smoke) due to incompletely burned tobacco products, lead and volatile organic compounds.

The issue of indoor air pollution comes to light especially during this period of the pandemic where people are cooped up at home. Indoor air pollution is also an area of concern at workplaces. Short-term health effects can arise due to exposure to high concentrations of indoor air pollutants which can cause eye irritation, headache, nose and throat irritation, fatigue, and dizziness. Long-term health problems can occur especially after years of exposure. Occupants are prone to suffer from heart problems, respiratory sickness, and even cancer. Building-related illness has been reserved for medical conditions of known origin that are usually discerned by objective physical signs and laboratory findings. Such illnesses include asthma, hypersensitivity pneumonitis and respiratory infections like Legionnaire’s disease. Sick building syndrome (SBS) is used to describe a situation in which the occupants of a building experience sudden or comfort-related effects that seem to be linked directly to the time spent in the building. In this case, no specific illness or cause can be identified.

The elderly and those with preexisting medical conditions are more susceptible to illnesses associated with air pollution. Infants and young children inhale more pollutants per kilogram of body weight than do adults. They have a higher resting metabolic rate and rate of oxygen consumption per unit body weight than adults. Children may also be less sensitive and tolerate higher doses of chemical substances than adults. The elderly are vulnerable to air pollution because the ability to eliminate chemicals from the body decreases with age. There is also increasing evidence that indoor air pollutants affect pregnant ladies.  Low levels of pollution may be associated with adverse birth outcomes. Formaldehyde, which is predominantly an indoor air pollutant is associated with reduced birth weight.

SARS-CoV-2 viral particles spread between people more readily indoors than outdoors. The lower the viral concentration, the less likely the virus can be inhaled into the lungs, be in contact with the eyes, nose, and mouth or fall out of the air to accumulate on surfaces. Good ventilation practices can reduce the airborne concentrations and reduce the overall risk of Covid-19 infection.

Routine daily cleaning performed effectively with soap or detergent can substantially reduce virus levels on surfaces. — Reuters pic

The Centers for Disease Control (CDC), USA recommends some ways to improve ventilation for better indoor air quality. One option is by opening windows and doors when weather conditions permit.  This is to allow cross ventilation and permit more light inside. Natural cross ventilation occurs when openings in dwellings or at workplaces are arranged on opposite or adjacent walls, allowing air to enter and exit. The system allows constant changes of the air inside the building.  Natural ventilation changes the air in the building through openings in the façade or roof. They result in lowered carbon dioxide levels for a fresh indoor climate. We recollect older buildings decades ago devoid of air conditioners where louvre windows were used at homes and at offices including at hospitals. They have an added benefit of natural ventilation. Horizontally running louvre blades lead to optimized climate control. Most of our buildings these days especially the offices are air conditioned and designed as ‘airtight buildings’ (windows closed or sealed). They may be the cause for diseases of modern architecture especially if they are poorly designed for ventilation which goes against the principle of dilution of pollutants.

CDC guidelines advocates the use of ceiling fans in low-speed settings to increase the effectiveness of open windows. Table or stand fans are to be directed towards an unoccupied corner and wall spaces or up above the occupied zone. Exhaust fans are to be left switched on. All ventilation and air conditioning systems require regular inspection and maintenance. Poorly maintained ventilation systems cultivate agents like viruses, bacteria, mould and fungi leading to health problems. Regular and thorough cleaning of places where biological pollutants are likely to grow will keep infectious disease at minimum. The risk of spreading Covid-19 virus through ventilation system is unclear at this point of time.

There are numerous technologies being heavily marketed to provide air cleaning during the ongoing Covid-19 pandemic. Current evidence to cleaning or disinfecting large and fast volumes of moving air within heating, ventilation, and air conditioning systems or even inside individual rooms remains debatable. Consumers are encouraged to exercise caution and to do their homework when purchasing these items. Registration alone, with national or local authorities, does not always imply product efficacy or safety.

According to CDC, the risk of people to be infected through contact with contaminated surfaces or objects (fomites) is generally low. Routine daily cleaning performed effectively with soap or detergent can substantially reduce virus levels on surfaces. Disinfection is recommended in indoor community settings where there has been a suspected or confirmed case of Covid-19 within the last 24 hours. However, there is little scientific support for routine use of disinfectants in community settings, whether indoor or outdoor, to prevent SARS-CoV-2 transmission from fomites.

We spend about 90 per cent of our time indoors at home, work, school, at shops or restaurants. Indoor air pollution receives little attention compared with air pollution. The authorities should focus their effort to educate the public on ways to improve indoor air quality in buildings including at homes. There is a Code of Practice on Indoor Air Quality introduced by the Department of Occupational Safety and Health (DOSH) to provide the guidelines and standards to protect the health of workers and other occupants of an indoor or enclosed environment served by mechanical ventilation and/or air conditioning. This code of practice is applicable in all non-industrial workplaces that are listed in First Schedule Occupational Safety and Health Act 1994. Under this practice, the building owner or building management shall establish a procedure to deal with complaint from employer and occupants related to signs and symptoms perceived to be due to indoor air quality. Upon receiving a complaint, the building owner or building management shall ensure that an investigation is conducted to ascertain the cause of the complaint, and a report prepared, without delay. It is time for DOSH to educate the public on this code of practice.

We are used to the fact that we have clean water coming from our taps. A quiet revolution is permeating within the global public health fraternity where we look forward to a paradigm shift on the scale where we can demand for a breath of fresh indoor air.

The change begins with us – be conscious about your own indoor air pollution footprint!

*Prof. Dr. Jayakumar Gurusamy is the Deputy Dean (Pre-Clinical) and a professor of Community and Occupational Medicine at the Faculty of Medicine, Manipal University College Malaysia.

**This is the personal opinion of the writer or publication and does not necessarily represent the views of Malay Mail.