Health and wellness

Seven eco-friendly, zero-waste ways to treat mould now it’s getting wet and warm

As Hong Kong’s warm, humid weather rolls in here are some options for eco-conscious residents to get to grips with the city’s common enemy

PUBLISHED : Sunday, 22 April, 2018, 8:01pm
UPDATED : Monday, 23 April, 2018, 7:05pm

Spring in Hong Kong means warm and humid conditions, which brings with it the blight of mould and mildew. They are not only unsightly, but can cause respiratory problems, allergic reactions, nervous-system disorders and even depression.

The annual battle to eradicate them often results in discarded footwear, upholstery, and even mattresses as fungal spores propagate, leaving few surfaces untouched by telltale green fuzz or black polka dots.

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Running a dehumidifier 24/7, hosing your flat down with fungus-fighting chemicals and stuffing enclosed spaces – such as wardrobes and drawers – with disposable moisture boxes can help get to grips with the problem, but these strategies are not so eco-friendly in the long term.

Plastic-packaged poisons and disposable boxes of silica, heating bars for the wardrobe and dehumidifiers running round the clock might keep the mould at bay, but they will run up your electricity bill, grow your carbon footprint and create unnecessary plastic waste.

For prominent zero-waste advocate Paola Cortese, whose Zero Waste Life programme teaches clients how to live more sustainably through reducing their personal waste footprint, environmentally friendly solutions must also be practical.

“It’s crucial to have a dehumidifier in the house,” Cortese says. “Yes, it’s electric and takes energy, but the health benefits far surpass the negative [aspects].”

However, there are ways to make the process greener, she says. “A zero waster can buy it second-hand from local sources,” Cortese says, recommending Hong Kong classified ad sources such as AsiaExpat, GeoExpat and Facebook buy-and-sell pages.

The appliance can either be sold on again for others to use, or disposed of sustainably via Alba IWS, a partnership between a German recycling specialist and a Hong Kong waste management firm that has a contract with the government to collect and process electronic waste at a purpose-built facility in Tuen Mun.

Parties either apply for collection, or drop off their unwanted large appliances at the facility, where the items will either be recycled or donated to local families.

As an extra step, Cortese says: “The customer can also offset the energy used by planting a tree with start-ups like EcoMatcher, for example.”

Proper ventilation in traditionally humid areas, such as in the bathroom or kitchen, is “an absolute must”, too, Cortese says.

The former interior designer likes to recycle used coffee grounds as passive moisture absorbers in containers left in the refrigerator, bathroom and wardrobes to reduce humidity, and says charcoal and chalk work similarly well.

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To treat outbreaks of mildew and keep mould from taking root, Cortese says: “I maintain the house with vinegar and water, and occasionally a dash of baking soda or used coffee grounds if I need a bit of scrubbing. Switching from natural loofah to metal scrubs works too for tougher stains.

“So far I have no mould issue at home with these simple steps.”

Here are some more green tips on how to beat Hong Kong’s common enemy.


1. Run exhaust fans in kitchens and bathrooms that can be turned off manually when not cooking or showering.

2. Clean up water spills straight away and fix leaky pipes or ceilings.

3. Make sure air conditioners are cleaned once a year to prevent mould build-up and ensure the machine is consuming energy as efficiently as possible.

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4. After showering, spray your shower with white vinegar to stop mildew growing on moist surfaces.

5. When purchasing an electronic dehumidifier, select a “grade one” energy efficient model with an eco mode that adjusts compressor speeds in response to humidity changes. The collected water might not be quite drinking safe, but it can be used to water plants, so less of it is wasted down the drain.

6. Make your own passive moisture-absorbing box dehumidifiers using water retaining granules, such as salt, rice, charcoal, coffee and chalk. Store them in an old lunchbox with a perforated lid, or repurpose “used” shop-bought damp traps.

7. When decorating, select eco-friendly, zero-VOC, mould-resistant paints, which are breathable and stop mould with high pH (potential of hydrogen) value instead of harsh chemicals.


1. Spray patches of mould with distilled white vinegar and leave to sit for an hour before wiping clean with water.

2. Dissolve a quarter of a teaspoon of baking soda in a spray bottle of water and apply to the mouldy area. Use a scrubbing brush to remove the mould, then rinse with water.

3. Add two teaspoons of tea tree oil to two cups of water and spray onto mould without rinsing.

4. Dilute 20 drops of citrus seed extract in two cups of water and spray onto mould without rinsing.