Thanks to modern air fresheners, we can rapidly get rid of any offending odour, failing which we can mask it with a more pleasant smell.

But do you know that synthetic air fresheners are among the main culprits of indoor air pollution? Synthetic fragrances, whether in solid, spray or oil form, may all emit harmful chemicals known as volatile organic compounds (VOCs), which start off as solids or liquids but readily evaporate into the air.

Recent research in the UK found raised levels of a VOC called limonene, used heavily in air fresheners and scented candles to give a lemony citrus smell. Limonene is dangerous to inhale on its own and can become formaldehyde – a carcinogen that burns the eyes, irritates the skin, and incites coughing fits, nausea, as well as nose and throat cancer – when it mixes with other airborne elements.

VOCs are present not just in air fresheners, but in all synthetic fragrances.

Research by a team from the University of Washington on 25 common fragranced consumer products —laundry products, personal care products, cleaning supplies and air fresheners, many of them top sellers in their categories— found 133 different VOCs emitted from the products, with an average of 17 VOCs per product. Of these 133 VOCs, 24 are classified as toxic or hazardous under US federal laws, and each product emitted at least one of these compounds. Among them are probable carcinogens (cancer causing) acetaldehydea, formaldehyde and methylene chloride.

More alarmingly, emissions of these compounds were not significantly different between “green” products and the other products. Of all VOCs identified across the products, only one was listed on any product label, and only two were listed on any material safety data sheet.

Every home has dust mites, tiny bugs that feed on human skin flakes; they can be found in mattresses, pillows, carpets, bedcovers, clothes, stuffed toys, and fabric and fabric-covered items.

Sensitivity to dust mites is often overlooked. Diagnostic tests and clinical studies by allergists have shown house dust mite to be the most common allergy among asthmatics, and an important “root cause” for the development of asthma in young children. Recent studies suggest that at least 45% of young people with asthma are allergic to house dust mites. Unlike “seasonal” allergies caused by moulds and pollen, people who are allergic to dust mites often will have symptoms year round.

As dust mites love moisture, we need to keep our homes’ relative humidity below 50% to minimise their growth. This would be rather challenging in Malaysia where the average relative humidity is way above 80%.

How can dust mites be eliminated then? Air conditioning and dehumidifiers can help reduce indoor humidity and slow their growth. Reduce the places where dust mites can grow. Clean surfaces and wash fabrics regularly.

The air conditioner (AC) does help improve indoor air quality as it circulates and filters indoor air. But beware; it can also become the main cause of indoor air pollution!

The substances that the AC removes from the air can build up inside the unit and re-circulate throughout the room. It can also become a fertile breeding ground for bacteria, viruses and other microorganisms. Refrigerants and other chemicals can leak from your AC as well, creating toxic vapours that are harmful to breathe.

Air conditioning pollution can cause dozens of diseases harmful to human health, mainly respiratory tract infections and allergic diseases.

Fortunately, all these can be avoided. Keeping your unit clean is something that can never be stressed too much. Make sure that you clean its filter regularly as dust can accumulate rather quickly. The condenser unit should be serviced at least once a year. Do have a professional carry out regular check-ups on your AC.

Most AC professionals advise changing your AC filter every three months. This is generally a good rule of thumb to follow. If you have not done so in a while, now is as good a time as any to replace the filter!

Given the dangers of indoor air pollution, we should adopt preventive measures to ensure that the air we breathe in our homes is safe. We have already adopted a healthy lifestyle by eating right, exercising regularly and drinking filtered water, so why disregard the air we breathe? The correlation between breathing in clean unpolluted air and longevity is undeniable. A high-quality air cleaner or purifier removes airborne particles such as dust, pollen and VOCs.