SINGAPORE - For more than a week, a cloud of fine ash from forest fires in Indonesia has shrouded Singapore, driving people to seek refuge indoors and scramble for masks.
The buzzword now is the Pollutant Standards Index (PSI), an index developed by the United States Environmental Protection Agency for reporting air pollution levels on a scale of 0 to 500. The index is based on concentration levels of pollutants such as sulphur dioxide, nitrogen dioxide, ozone, carbon monoxide and particulate matter of 10 microns or smaller, called PM10.
Last Friday, the three-hour PSI reading, an average of readings in the past three hours, hit a record high of 401. The previous record was 266 in 1997.
The health impact of the haze depends on both the pollutants' concentration level and how long people are exposed to them.
The Ministry of Health said haze particles may irritate the eyes, nose and throat in healthy individuals. In most cases, the irritation resolves on its own.
The haze may aggravate existing symptoms in people with chronic heart or lung disease, such as heart failure, asthma and chronic obstructive pulmonary disease, doctors warned.
These effects may not be apparent until one to three days later, the ministry said.
A study on the health impact of the haze in 1997, published in the journal Respirology in 2000, found that an increase from 50 micrograms per cubic metre (mcg/m3) of PM10 to 150mcg/m3 was significantly associated with a 12 per cent rise in the number of patients with upper respiratory illnesses. In those with asthma, it was up by 19 per cent and in those with rhinitis, by 26per cent.
Though haze particles are carcinogenic, a person has to be exposed to them for a prolonged period - such as more than 10 months in a year - before his risk of lung cancer rises, said Dr Wong Seng Weng, the medical director of Singapore Medical Group's The Cancer Centre.
This is unlikely to happen here, so people should not be unduly worried, he said.
Risk of heart attack
Risk of heart attack
Associate Professor Philip Eng, a consultant respiratory physician at Mount Elizabeth Medical Centre, said the haze can trigger asthma-like symptoms in healthy people. These include shortness of breath, chest congestion, wheezing and coughing.
Normally, the nose filters inhaled air through the hairs and mucus.
Particles that are 2.5 microns or smaller, called PM2.5, can bypass this natural defence mechanism to enter the lungs. This sets off an inflammatory reaction in the airways, triggering symptoms in healthy individuals and worsening the symptoms of those with existing respiratory illnesses, Prof Eng said.
He likened asthma that is not well-controlled to having a raw wound in the breathing tube, which then becomes inflamed more easily.
Those with a runny nose can take pills called antihistamines, which combat allergy symptoms.
Prof Eng said symptoms such as breathlessness, fever or chest pains should warrant a trip to the doctor.
Dr Tan Chong Hiok, a cardiologist at Mount Elizabeth Medical Centre, said PM2.5 can enter the bloodstream through the lungs.
The particles are deposited in the arteries, triggering an inflammatory reaction, which activates platelets in the blood that help it clot. This predisposes a person to blood clots that can result in fatal heart attacks and strokes, he added.
A study reported in the journal Circulation in 2001 suggests that elevated concentrations of PM2.5 may increase the risk of heart attacks for several hours as well as for several days after exposure.
Dr Tan warned that the haze may cause people with coronary artery disease to experience worsening angina (chest pain), while those with heart failure may see a drop in effort tolerance - that is, they may feel breathless more easily.
Those with worsening angina should see a doctor immediately, he said.
Dr Lim Li, the head and senior consultant at the corneal and external eye disease service at the Singapore National Eye Centre, said exposure to the haze can cause eye irritation and conjunctivitis, an infection commonly called red eye.
The person will experience symptoms that include a burning sensation, redness and tearing of the eyes. While these do not harm vision, they cause discomfort.
Smoke exposure can also exacerbate symptoms for patients with existing eye diseases, especially those with dry eyes.
Dr Lim advised people to wear spectacles instead of contact lenses, which dry the eyes.
Those who are exposed to a dusty environment should use protective eyewear such as goggles, she added.
To relieve eye irritation, use preservative-free artificial tears, which can be bought over the counter, she said. Cold compresses may also help, she added.
A person who experiences poorer vision, increasing eye discomfort with significant eye discharge or worsening symptoms despite medication should consult an ophthalmologist, she advised.
Dry skin and rashes
Dr Lynn Chiam, a dermatologist at Mount Elizabeth Novena Hospital, said the haze causes the skin - a barrier between environmental pollutants and the body - to be overwhelmed, such that those with no history of skin ailments can also develop skin problems.
She said: "The haze, dust and dirt in the air can clog pores and lead to pimples. Long-term exposure to pollution can irritate the skin, leading to dry, rough skin and a rash."
In addition, air pollution increases the production of free radicals (toxic by-products of oxygen) in the skin, which damage cells in the body.
Prolonged exposure to air pollution can cause wrinkles and premature skin ageing, said Dr Chiam.
Healthy people should apply moisturiser on their skin to improve its barrier function. Using moisturiser regularly - at least twice a day, once in the morning and once in the evening - can prevent skin from drying and reduce itch, Dr Chiam said.
Avoid using harsh soap, which can further damage the skin barrier.
Those with eczema and psoriasis, whose skin barriers are weakened, are more susceptible to the haze and their skin conditions may flare up, causing rashes and itch, she added.
So they need to cover areas of broken skin to protect it from the dirt and toxins in the air, Dr Chiam said.
They also have to avoid contact with hot water and scratching their skin, she added.
People with broken skin and wounds need to see a doctor to get cream to prevent infection, she said.
Others with a red, itchy rash that is not alleviated with moisturiser also need medical attention.
Eat well to stay healthy
Eat well to stay healthy
Doctors advised people to stay indoors as much as possible and keep the doors and windows closed. They should switch on the air-conditioner or use air purifiers to filter the air.
The Ministry of Health recommends that people avoid vigorous outdoor activity once the PSI crosses 200. During exercise, a person inhales faster and harder and, hence, may breathe in more harmful haze particles.
The National Environment Agency said healthy people need to wear masks only if the PSI goes beyond 200 and they cannot avoid prolonged and strenuous outdoor activities.
People can also keep up their immunity by consuming the necessary nutrients. These include vitamins A, B, C, D and E, minerals such as zinc, selenium, iron and copper, and omega-3 fatty acid, which has an anti-inflammatory effect, said MrDerrick Ong, dietitian and director of Eat Right Nutrition Consultancy.
Whole grains are rich in vitamin B, while fruit and vegetables are full of folate (vitamin B9) and vitamin C. Nuts, seeds and legumes are good sources of vitamin E and selenium.
Meat, fish and seafood contain zinc and omega-3 fatty acid.
Mr Ong said: "No single type of food can boost the immunity, particularly against respiratory illnesses. But there is some evidence to suggest that cod liver oil, a significant source of vitamins A and D and omega-3 fatty acid, may reduce the incidence of respiratory tract infections among children."
The general rule of thumb is to have a balanced diet, plenty of fluids and sufficient sleep, he added.
How to wear the N95
Here is a step-by-step guide to wearing an N95 mask correctly.
1. Wash your hands before putting on the mask.
2. Select an N95 mask of a suitable size.
3. Position the mask under the chin with the nose clip facing up. Place the mask firmly over the nose and mouth with a cupped hand.
4. Stretch and position the bottom strap at the back of the neck below the ears. Position the top strap at the back of the head above the ears.
5. With the fingertips of both hands, gently press the top of the nose clip and mould it to the shape of your nose. Do not pinch the nose clip.
6. Perform a fit check by inhaling and exhaling. During exhalation, check for air leakage around the face. If there is leakage, re-adjust the mask.
Sources: Health Promotion Board and Dr Lee Lay Tin, head and senior consultant at the occupational health department at Tan Tock Seng Hospital
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