Indoor Air Quality In the New Normal

Indoor Air Quality In the New Normal

According to the Department of Occupational Health and Safety (DOSH), “Indoor air quality describes how inside air can affect a person’s health, comfort, and ability to work. It can include but is not limited to temperature, humidity, mould, bacteria, poor ventilation, or exposure to other chemicals”. As per the United States Environmental Protection Agency (EPA), IAQ can be at least 2 to 5 times worse than outdoor air quality, and in some cases, it can be even up to 10 times worse!

Consequences of Poor IAQ

Some of the short term effects of poor IAQ include irritation of the eyes, nose and throat, headaches, dizziness, fatigue, allergy and asthma. Generally, it can lead to discomfort, ill health, absenteeism and lower productivity. Certain immediate effects are similar to those from colds and other infectious diseases that are transmitted through the air, and “sick building syndrome” symptoms due to elevated indoor pollutant levels. Some effects may be further aggravated by inadequate ventilation or humid conditions indoors. Other long-term health effects that may show up after years of exposure to poor IAQ include respiratory diseases, heart disease, lung cancer, carbon monoxide poisoning and Legionnaires’ Disease.

Sources of Indoor Air Pollution

Indoor pollution sources that release gases or particles into the air are the primary cause of indoor air quality problems. Inadequate ventilation can increase indoor pollutant levels by not bringing in enough outdoor air to dilute emissions from indoor sources and by not carrying indoor air pollutants out of the area. High temperature and humidity levels can also increase concentrations of some pollutants.

There are many sources of indoor air pollution including kitchen stoves, tobacco, building materials and furnishings, household cleaning and maintenance products, and personal care, air-conditioners and humidifiers, excess moisture, radon, pesticides, formaldehydes, Volatile Organic Compounds (V.O.C.) and outdoor air pollution.


Based on the above effects of poor IAQ, it can already be seen that ‘’flu-like’’ symptoms can be caused by the existing pollutants in the air including mould spores and dust, in part due to contaminated air-conditioner cooling coils as a result of humidity. Poor IAQ leads to lower immunity, making people susceptible to being infected by viruses.

During the Movement Control Order (MCO) isolation period, many buildings have been left unoccupied and unattended, resulting in higher humidity which in some places have led to mould contamination. They will need to be decontaminated before being occupied again or else the ‘’Sick Building Syndrome’’ will cause people to have lower immunity. Places with water retention like cooling towers, leaky air-conditioners and water dispensers may be at risk of Legionnaires’ Disease, another deadly respiratory disease.

Infectious diseases like the COVID-19 can also be spread by the air-conditioner air flow as was seen in a recent article published in the Emerging Infectious Diseases Journal for US Centres for Disease Control and Prevention (CDC), largely due to poor air ventilation. Although this setting was at a restaurant, it is applicable to any air-conditioned environment including offices, schools, malls and factories.

The correlation of virus spread via the air-conditoner at a restaurant in Guangzhou, China

How a restaurant air-conditioning unit caused nine diners to be infected with COVID-19 from January 25 to February 5.

Read full article by Mr Michael Folk: Indoor Air Quality in the New Normal

Article by GreenRE: GreenRE Bulletin

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