Improving air quality indoors during self-isolation for Covid-19

Tips for cleaning the home during self-isolation and improving air quality indoors with pot plants.

In order to stem the spread of Covid-19, several countries across the world are under lockdown, with people being forced to stay indoors, with only brief forays allowed outdoors for a little solitary exercise or some essential shopping.

It seems South Africa is not far behind, and social distancing is now a reality, with more and more people working from home, and the elderly staying indoors as much as possible. This is all good and well, but what most folk do not realise is that the air in our homes is typically up to five times more polluted than the air outside.

Indoor air pollution is a well-known fact, with gaseous chemicals like formaldehyde and benzene being classified by the Environmental Protection Agency (EPA) as known human carcinogens. These are found in a number of household items including paint, pressed-wood furniture, plastic bags, computer ink, carpeting, and household cleaners. According to the EPA volatile organic compounds are one of a variety of pollutants that are currently so pervasive, that indoor air is now two to five times more polluted than outdoor air.

When NASA scientist, Bill Wolverton tested houseplants in lunar space stations for their detoxifying potential he came up with some intriguing findings. Barberton Daisies (Gerbera) removed benzene from the air and Peace Lilies (Spathyphullum) removed a noxious substance known as trichloroethylene, while Devils Ivy (Scindapsus) and Philodendrons, reduced airborne formaldehyde. His research stimulated further studies and in 1994 a German report proved that only one Spider Plant (Chlorophytum comosum) could detoxify a 100 cubic-foot room, polluted with formaldehyde, in only 6 hours.

Some studies have suggested that houseplants can reduce fatigue, coughs, sore throats, and other cold related symptoms, and may help lower blood pressure and improve concentration, so next time you are out shopping, grab a couple of indoor potted plants – if you are cooped-up at home, they will also give you a lot of pleasure. Remember to keep them out of reach of small children and pets because many of them are poisonous if ingested. 

To rid the home of indoor air pollution use an average of one indoor plant or tree for every nine square metres. In the plant's natural process of respiration, it will absorb your toxic waste while adding oxygen and moisture to the air. Within 24 hours some plants will already be removing up to 87% of indoor air pollution

Adding houseplants is a simple and beautiful way to help detox your home, because many common household cleaners are listed amongst these pollutants, if you are planning on taking advantage of confinement measures to do some thorough spring-cleaning, you should be wary of overusing industrial cleaning products, and you should clean in a well-ventilated room with the windows open.

 Also if money is tight and you are on a strict budget, there are cheaper options which are just as effective for cleaning. Traditional hard soaps, bicarbonate of soda, and white vinegar are precious natural allies in the bid to keep your home hygienically clean. These four traditional cleaning products are all that you need to clean all types of surfaces.

Bicarb is good to clean most surfaces, and is great for scrubbing pots and pans.  Traditional hard soaps can be grated and melted down in hot water to make a general purpose household cleaning detergent which can also be used for washing clothes and other surfaces, and vinegar is a good sanitiser for all glazed modern surfaces, and especially glass.

Another easy way to clean the air inside is to air your home several times a day, but especially early in the morning and in the evening before going to bed, as well as after cooking or cleaning.  Do not smoke indoors, especially around children, tobacco smoke leaves lasting traces on walls, fabrics, floors and ceilings, and inhaling the air in an enclosed space polluted by tobacco increases the risk of heart disease and respiratory disorders.

Some people are raising questions about the role of indoor air-filtration systems and their efficacy in protecting us from the virus. Most public health guidance suggests that COVID-19 transmission is predominantly associated with large droplets.  Although filtration in buildings and air conditioning systems may be used as part of an overall risk mitigation approach, they are not generally regarded as a solution by themselves and there is no direct scientific evidence of benefit. However, some reduced exposure can reasonably be inferred based on the ability of some filters to remove relevant-sized particles and droplets.

Also, bear in mind that in order for air filters to have any real impact on the spread of infectious diseases, the filters have to be appropriately designed for your home, and properly installed and maintained. This is why air filtration is only a small part of the solution.

 If you already have an air conditioner use it, but if it has not been cleaned for a long time, do so now. DNA and RNA from other viruses that are generally associated with droplets have been found on used air filters, so precautions should be taken when changing filters, and this becomes particularly important in a building or home where there are known or possible cases of any infectious disease including COVID-19, and also extends to portable air cleaner filters and vehicle air filters.  Filters should be changed with the system turned off, while wearing gloves and a face mask if possible, and disposed of in a sealed bag.

There is no direct clinical evidence of the benefit of portable air cleaners for reducing infectious disease risk, but some benefit can be reasonably inferred for portable HEPA filters, provided they are appropriately sized i.e., their removal rate is appropriate for the size of the room. They also need to be properly maintained and operated. HEPA filters are used in applications that require contamination control, such as the manufacturing of disk drives, medical devices, semiconductors, nuclear, food and pharmaceutical products, as well as in hospitals, homes and vehicles.  As with building filtration, they are only likely to be effective in concert with other measures.

Many folk are wondering about ultraviolet (UV) lamps, and if they work? Yes, a properly designed and maintained UV system, often in concert with filtration, humidity control, and airflow management, has been shown to reduce infections from viruses, however, the details of the system are very important (e.g., design of fixtures, lamp type, lamp placement, airflow amount and mixing, etc.).  Simply adding UV to an existing system without consideration of these factors has not been demonstrated to have a benefit.

What about ionizers, ozone generators, plasma, and other air cleaning technologies? Although these have shown promise in controlled tests done in laboratories and other idealized settings, none of these technologies have been proven to reduce infection in real buildings, but if you already have these and you love using them in your home, why not continue to use them?

Here are some of the best potted plants to clean the air:

Barberton Daisy (Gerbera hybrids)

These plants produce flowers for many months in summer if placed in a warm room with bright light. They are specially bred to grow indoors and don't like too much direct sun, but a some morning sun won't harm them. Water them regularly in summer, less in winter and feed them every two weeks when they are in bloom. They require very well drained soil. 

They remove benzene from the air, released by tobacco smoke, printers, photocopiers, floor and wall coverings, particleboard, adhesives, paints, stains and varnishes.

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Chrysanthemums originate in East Asia and there are about 40 species. Their exquisite shapes, and kaleidoscope of colours, make them the most alluring pot plant. You can really match them to your decor. Place them in a warm, bright position indoors and water them when they are almost totally dry. Do not

Chrysanthemums absorb Benzene, released by tobacco smoke, printers, photocopiers, floor and wall coverings, particleboard, adhesives, paints, stains and varnishes.

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Peace Lily (Spathyphyllum)

This family of plants  belongs to the arum lily family. They have attractive, dark green leaves and beautiful white to green flowers. They will flower in low light levels but grow best in a warm, bright position indoors. They enjoy humidity, so spray the leaves down with tepid water often. Plant them in deep, fertile, well-drained soil and water and feed them regularly.

This plant and absorbs alcohols, trichloroethylene (a dry-cleaning chemical), formaldehyde, and benzene from the air in your home. It removes acetone (an ingredient of plastic), benzene (present in glue), trichloroethylene (found in printers) and xylene (emitted by computers).

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Devils Ivy, Golden Pothos  (Scindapsus)

These climbing plants from the Solomon Islands are grown for their lovely shiny leaves. They are mostly trained to climb up moss filled poles but can also be planted in hanging baskets. Devils Ivy is very easy to grow indoors in moderate to good light. They like good well-drained soil and require high humidity to look at their best. Spraying the leaves and stems down regularly with tepid water increases humidity and will keep them clean and healthy. Water them regularly in summer, less in winter and feed your plant once a month with a water soluble plant food that is high in nitrogen.

Devils Ivy reduces airborne formaldehyde.

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Boston Fern (Nephrolepis exaltata)

The Boston fern adds a elegant charm and classic beauty to any home. They like a warm (not hot) position indoors with good light but no direct sunshine. Keep them away from cold draughts. Humidity is essential to Boston ferns, so mist spray the leaves daily with tepid (not cold) water and place the pots on drip trays filled with gravel and a little water. In summer, keep the soil evenly moist but not saturated; never allowing the soil to dry out totally. In winter, allow the surface of the soil to become a little dry before watering. During summer feed with a water soluble, high nitrogen houseplant food like Nitrosol; diluted to half of the recommended strength.

This plant adds humidity and ranks best at absorbing formaldehyde (found in carpeting and pressed wood, paint and shelving) and the solvents found in furniture and floor wax.

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Corn Plant (Draceana)

There are many exciting varieties of Corn Plants. They come mostly from Africa with species in most tropical regions and two that are endemic to the Canary Islands. Some have broad, striped leaves while others have delicate, thin leaves. They vary in height but will slowly form tall bare stems, topped with gracefully arching leaves. Corn Plants are excellent to use in darker areas indoors and will grow easily in artificial light in offices etc. Plant them in good, well-drained potting soil and water them regularly but do not over water. Feed once a month.

The Corn Plant absorbs trichloroethylene from the air in your home. Found in inks, paints varnishes, lacquers, adhesives and  dry cleaning.

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Spider Plant (Chlorophytum comosum)

The Spider Plant is a popular houseplant with both green and variegated varieties. It is especially popular plant with beginners, as it is easy to grow and is very tolerant of neglect; being able to thrive in a wide range of conditions. They need bright natural light indoors and can get sunburnt if grown in too much direct sunlight. They also do very well when grown under grow lights, but will be reluctant to produce the plantlets unless you decrease their light hours to simulate the naturally shorter days of autumn, when they normally produce their 'babies'. Keep the soil evenly moist, but never soggy. Feed the plant every 3 or 4 months with any pot plant fertilizer.  Over fertilizing will damage the plant, so when you feed use 1/2 of the recommended strength. On mature plants the tips of the leaves can go brown and this is generally caused by chemicals in the water.  Using rainwater or distilled water will take care of this problem.

Researchers at the US based National Space Technology Laboratories found that a single spider plant enclosed in a room filled with formaldehyde (found in air fresheners and detergents) removed 80% of pollutants in only one day. If you have a gas geyser in the bathroom, the spider plant will help clear the carbon monoxide from the air as well.

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Rubber Plant (Ficus elastica)

This popular pot plant is very easy to grow and care for. It is a vigorous grower and doesn't ask for much attention. It will tolerate low light indoors but try to avoid really dark places, as this will cause the plant to become weak and spindly. Brown, dead spots on leaves are usually scorching, a sign that your plant is getting too much light. These plants can grow ten or more feet high indoors, so pruning is advisable to keep it in an attractive form and acceptable size. The Rubber Plant likes a well-drained soil. Avoid over-watering, but don't let it dry out totally either. Symptoms of over-watering and under-watering are similar, such as leaf yellowing and leaves falling off.  Watering once a week is a good place to start, but adjust your schedule depending on how quickly the soil dries out. You should also water slightly less often in the cooler months when the plant slows down its growth. Fertilization is not really necessary, but can be done once a month with a water soluble fertilizer, if you like.

Removes formaldehyde found in upholstery, clothes, facial tissues, paper towels, grocery bags, gas stoves, carpeting, particleboard, plywood, adhesives, paints, stains and varnishes, foam insulation, paper goods, household cleaners and water repellents.



Weeping Fig (Ficus benjamini)

This elegant potplant is grown for its gracefully, drooping branchlets of glossy dark green leaves. It grows best in warm rooms with bright light but will tolerate darker areas. There are numerous cultivars with different leaf variegations, ranging from dark to light green, golden yellow and white. It requires a moderate amount of watering in summer, and only enough to keep it from drying out in the winter. Never overwater this plant or it will suddenly drop its leaves. The leaves are also very sensitive to small changes in light and often if it is relocated to another position indoors, it reacts by dropping many of its leaves, replacing them with new leaves adapted to the new light intensity. The plant is sensitive to cold and should be protected from drafts, especially in winter.

The Weeping Fig has been shown by NASA to effectively filter most indoor air toxins and helps remove formaldehyde.  Formaldehyde is the most common indoor toxin that is found in most cleaning products. It also works well to remove chloroform which is found in dyes and pesticides.

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Golden bamboo palm  (Chrysalidocarpus lutescens)

This graceful palm remains the most popular pot plant and will grow beautifully indoors if it is placed in moderate to bright light indoors. If it receives too much direct sunlight indoors the fronds may get burnt. Water it well throughout the year, but more moderately in winter in cold regions. It likes well-drained soil and needs to be sprayed down regularly with tepid water to increase humidity around the leaves. This is especially necessary in cold, dry regions of the country. Misting with water will prevent brown tips on the leaves, caused by lack of humidity and keep the plant clean and healthy as well. Standing the plant on a drip tray filled with pebbles and a little water will also help to increase humidity. Never allow the pot to stand directly in water or it could rot.

A large palm is fantastic for cleaning indoor air as it transpires one litre of water every 24 hours. This high transpiration rate makes this plant among the best for removing benzene, found in varnish and the chemicals found in plastic toys. It effectively removes xylene and toluene, found in paint.

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There are many varieties to choose from, ranging from tall climbers with large attractive leaves to the more delicate, smaller growing ones. They are normally trained to climb up moss filled poles but some varieties will cascade and are planted in hanging baskets. These climbing plants enjoy high humidity. They grow easily indoors in moderate to subdued light. Water them regularly in summer and spray the plants down with tepid water regularly to increase humidity. Feed monthly with a water soluble pot plant food that is high in nitrogen.

Philodendrons remove formaldehyde, the most common indoor toxin  found in most cleaning products, upholstery, grocery bags, gas stoves, carpeting,  paints, stains and paper goods

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There is a vast array of orchids to choose from for the home, from  large growing specimens to tiny dwarf varieties. There are those that that thrive in sun and those that prefer subdued light. If they are placed in the correct position indoors and watered and fed correctly, they can give you many years of pleasure. Orchids are more active at night and will work harder than any other plant to purify and re-oxygenate the air while you sleep.

Dendrobium orchids are effective at removing acetone, an ingredient of plastic and formaldehyde, found in carpeting, pressed wood, paint and shelving.

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English Ivy (Hedera helix)

Ivy is used successfully indoors as a foliage plant. It is excellent for hanging planters and other applications which require a cascading or trailing plant. The small-leaved cultivars are especially attractive indoors and can be trained into formal shapes on trellises and made into topiary figures. Ivy makes a good ground cover for interior planting beds and the soil surface of large free-standing planters containing interior trees. Ivy loves a well-drained, peat-based potting media which has a high water-holding capacity. It can be grown in medium to bright filtered light very successfully. The plants may be grown under sunlight, but too much direct sun can cause the leaves to become pale or develop brown necrotic areas. Sunlight may be supplemented with electric lighting or fluorescent tube lamps. Feed every two weeks during the growing season with a water soluble fertilizer.

Ivy is a good remover of formaldehyde, benzene, toluene, xylene and trichloroethylene from the atmosphere.

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Azalea (Rhododendron

These popular garden plants are grown indoors for their breathtaking blooms in shades of pink, red, white, purple, lilac and even orange. The flowers can be tiny or large, single or double. They will grow easily indoors if their specific needs are met. Place them in a warm (not hot) room, with good light. They love high humidity and enjoy being sprayed down often with tepid water. Placing the pots in drip trays filled with gravel and a little water will help to increase humidity around the leaves. Let the soil to dry out partially before watering but never allow it to dry out totally. Re-pot into a slightly bigger pot after they have finished flowering. Use a rich potting soil with added peat and ensure that it drains well. If your plants need pruning it can only be done when they are finished flowering because azaleas flower on last seasons growth. Pruning too late will affect flowering.

Azaleas remove Formaldehyde, found in upholstery, clothes,  gas stoves, carpeting, paper goods, household cleaners etc.

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