KUALA LUMPUR: As Malaysians continue to spend a bulk of their time indoors amidst the Covid-19 pandemic, experts have cautioned against serious health risks that could stem from indoor air pollutants (IAP) if adequate measures are not taken.
While most people are aware of the dangers of ambient (outdoor) air pollution, they said not many realise that IAP could be more detrimental, especially to children, the elderly and those living in suburban and urban areas due to their 'airtight homes' and poor ventilation.
Routine activities such as cooking on the stove, mopping the floor with chemical solvents, installing new furniture, and even lighting candles could push indoor air pollution to dangerous levels, they said.
Malaysia Clean Air Society deputy president Professor Dr Juliana Jalaludin said people generally spend, on average, 60 per cent of their time indoors, while children about 80 to 90 per cent and infants 100 per cent.
The senior academician, researcher and consultant in the fields of Environmental, Occupational Health (Air Quality and Exposure Assessment) and Occupational Epidemiology at Universiti Putra Malaysia said this includes time spent in homes, offices, schools, and daycare centres.
"The percentage is estimated to be higher during the various Covid-19 movement restrictions, which means we now face greater exposure to IAP due to longer duration spent indoors.
"Not many Malaysians are aware of this issue. Most of us know that it can be harmful to breathe in polluted air outside but even the air in our own home could be toxic, especially for children and people with health conditions such as asthma.
"Due to their invisibility, these IAP are considered hidden threats and IAP is usually higher in concentration than ambient air pollutants especially in urban areas, which are near to traffic, construction sites, landfill, mining areas and industrial complexes.
"High temperature and humidity levels indoors could also increase concentrations," she told the New Straits Times.
According to the United States' Environmental Protection Agency, IAP in homes could be two to five times higher than typical outdoor concentrations and estimated that on average, people spend about 90 per cent of their time indoors.
It also found that concentrations of many VOCs (which are carbon-containing organic chemical) are up to ten times higher than outdoors.
A study done in Malaysia, titled "Indoor and Outdoor Exposure to PM2.5 during Covid-19 Lockdown in Suburban Malaysia", published in November 2020, noted a potential for greater exposure to fine particles indoors than outdoors while under lockdown.
Juliana said increased and regular indoor activities can cause spikes in substances such as volatile organic compounds (VOC), nitric oxide, carbon dioxide, and fine particulate matter (PM), which can harm health at high levels.
Other sources of indoor pollution, she said are building and construction materials, furnishings and outdoor air quality and pollutant such as from traffic sources and activities in urban and industrial complexes which could penetrate indoors through cracks and walls.
"Common contaminants found in houses are respirable dust and fine dust which are particulate matters less than 10 micrometres and 2.5 micrometres (PM10 and PM2.5).
"There are also VOCs from a large number of sources including household and beauty products, chemical detergents, cleaning supplies, building materials, air fresheners, fragrances, tobacco smoking, printers, and indoor chemical reactions.
"Formaldehyde is one of the most common indoor VOCs from pressed wood, laminated floors, carpets and paints. Other contaminants are moulds and dust mites, internal emissions from cooking."
In a 2019 study, researchers cooked a Thanksgiving dinner in a test home and found that levels of PM reached as high as 285 micrograms per cubic meter (μg/m3). In comparison, PM levels in New Dehli, which has poor air quality, average around 225 μg/m3 during the dirtier winter months.
Juliana noted that one of the ways to identify IAQ problems is by assessing for signs of ventilation issues such as stuffy or smelly air, moisture on ceilings or walls, and areas where items become damp and mouldy.
She said short-term or acute impacts of IAP exposure were often associated with sick building syndrome (SBS), which includes eye irritation, itchy and dry skin, headache, fatigue, dizziness, nausea, rashes, rhinitis, and increased respiratory symptoms such as cough, phlegm and chest tightness.
Long-term or chronic impact include reduction of lung function, heart disease, loss of productivity, genotoxicity, neurological effects, genetic damage, cancer, and chronic respiratory illnesses such as environmental asthma, she said.
The World Health Organisation (WHO) revealed that each year, close to four million people die prematurely from illness attributable to household air pollution where most perish from stroke, ischaemic heart disease, chronic obstructive pulmonary disease, pneumonia and lung cancer.
Juliana said children are one of the populations mostly affected by IAP. Others are the elderly, infants, pregnant women, immunocompromised individuals and those who reside or work near the source of air pollution.
"Due to Malaysia's tropical climate, children are exposed to fungal toxins, mycotoxins, endotoxins and allergens (found in homes and classrooms).
"One of my studies found that exposure to IAP, especially from mosquito coil smoke, was associated with impaired lung function and increased risk of acute and chronic respiratory symptoms among the exposed children.
"IAP in schools partly originate from outdoor pollutants. For instance, PM2.5, PM10 and nitrogen dioxide (NO2) were commonly found in schools located near to heavily travelled roads; NO2, sulphur dioxide, and VOCs in schools near industrial complexes; and PM10 and PM2.5 in schools near construction sites."
One of the VOCs found in schools located near a petrochemical area is polycyclic aromatic hydrocarbons, which is highly toxic, mutagenic, carcinogenic, teratogenic, and immunotoxicogenic, she said.
Common contaminants in offices include VOCs, PM2.5, PM10 and moulds, she added.
Consultant paediatrician and Malaysian Paediatric Association committee member Datuk Dr Zulkifli Ismail said of late, there have been increased incidents of childhood allergies as their houses and apartments were situated near major highways and busy roads.
"There is now a rise in allergic symptoms affecting children's nasal passages and skin which may be precipitated by IAP."
He said children are more susceptible to illnesses associated with air pollution because their immune systems are "naive" but can be very reactive.
If a child has an allergic preponderance, he said this sets a cascade of immune reactions that cause skin irritation, nasal passage irritation, bronchial wall hyperactivity and may result in narrowing of these airways culminating in wheezing as seen in asthma.
"The smaller lungs and narrower airways of children make them more susceptible to wheezing and the need for admission in hospitals.
"They may also have a prolonged cough which will not be treated properly with usual medication until the allergen is removed. Chronic runny nose may be given unnecessarily prolonged antihistamines if pollutants within the child's nostrils at home are not identified and removed."
Dr Mohd Talib Latif, a professor of Atmospheric Chemistry and Air Pollution at Universiti Kebangsaan Malaysia said common IAP sources could be categorised into three broad categories - suspended particle and dust; gases including VOCs such formaldehyde and benzene; and biological contaminants including, mould, bacteria and virus.
"We need to pay attention to indoor environment. People who are most at risk are those who live in confined spaces with poor ventilation system and in an urban environment such as Kuala Lumpur.
"In many cases, confined space in an indoor environment has limited dispersion processes due to an ineffective ventilation system. Air pollutants can stay longer in indoor air compared to ambient air."
Talib, who is the Chairman of the Sustainable Resources, Environment and Smart Living Research Cluster, Centre for IDEA-UKM said indoor environment could be assessed based on physical conditions of the area such as dusty condition, uncomfortable smell, and the existence of fungi.
"There also several affordable instrument or sensors for us to check suspended dust concentrations and gases air pollutants. These instruments usually can give an estimation of air quality conditions."
Dr Md Firoz Khan, a Senior Lecturer in the Department of Chemistry, University Malaya said among the air pollutants, airborne PM is a potential toxic pollutant that is a mixture of inorganic and organic components in the atmosphere.
"Some of the chemicals in PM is hazardous and toxic for human. It can pass through our respiratory system and causes diseases such as coughing, asthma, and shortness of breath."
Firoz shared that while the Malaysian government had in the past shut down schools to protect children from exposure to smoke during haze pollution, reported literature showed that the IAQ deteriorated by five to 10 times compared to outdoor ambient air.
"Many US and Canada researchers have stated that indoor air is a mixture of PM2.5, CO, VOCs, oxides of nitrogen, metals, ozone that generates reactive oxygen species (ROS) and free radicals.
"ROS directly affects the inflammation of cell and DNA damage. Therefore, it is a very challenging issue for further discussion."