Indoor Air

​Indoor Air

Excerpts from an article in Non-Toxic Times, 2/04

The real power of plants lies in their ability to remove unhealthy chemicals from our indoor air.

Studies have shown that the atmosphere in rooms filled with houseplants typically contains between 50% to 60% fewer mold spores and bacteria.

Plants accomplish this task in two main ways.

The first is by literally absorbing chemicals in the air via microscopic leaf openings called stomata. Once absorbed inside, the plant either breaks down the pollutant in question, or it sends the contaminant down to its roots where its released as food for the colonies of microbes that typically live in a plants root zone.

These harmless organisms are a key factor in a plant's ability to purify air. Plants of all kinds have evolved to depend on bacteria to break down soil debris into food that can then be taken up by their roots. It's a symbiotic relationship in which plants have developed the ability to actually culture their own microbial colonies. In this ancient system, plants provide food to the bacteria and the bacteria convert this and other food sources into nutrients the plant itself can then utilize.

As luck would have it, this food cycle can include toxic chemicals absorbed by the plant. Once absorbed by stomata and transferred to the roots, microbes are able to break down a wide variety of unhealthy compounds into materials the plant can then re-absorb as food.

These pollutants are also delivered to soil bacteria by a mechanism known as transpiration. In this process, the water vapor a plant emits through its leaves rises away from the plant and into the atmosphere. As it does so, it creates convection currents of air that move in the opposite direction. Heading down toward the base of the plant, these currents draw pollutants into the soil where they're rendered harmless by bacteria living there.

Using plants to effectively purify indoor air requires more than a few.

Homes with indoor air problems as well as healthy homes seeking to stay that way won't be able to accomplish their aims with a handful of potted plants on a windowsill. On the other hand, it's by no means necessary to live in a virtual jungle in order to realize appreciable atmospheric benefits.

Placing houseplants in reasonable abundance throughout the home will result in a healthier atmosphere than that found in a home where no plants are present at all.

(It should also be noted that while houseplants can remove many VOCs and other gaseous compounds, they don't do anything to help with other indoor air hazards like particulates, dust, radon, etc.)

Because the amounts and types of individual pollutants removed by plants differ from species to species, and because the levels of specific pollutants often vary significantly from home to home, there's no set number of plants recommended by experts for maximum results.

Instead, the general rule of thumb is the more plants the healthier the air. This purification power can be maximized by choosing those plants found to have the greatest air cleaning abilities. Following is a list of 20 of the top choices for removing gaseous pollutants from indoor air. Exceptional abilities are noted where applicable.

Boston fern (Nephrolepis exaltata Bostoniensis) – This plant is number one plant in overall purifying performance.

Areca palm (Chyrsalidocarpus lutescens) – Another top overall performer.

Lady palm (Rhapis excelsa)

Bamboo palm (Chamaedorea seifrizii) – One of the top rated plants for formaldehyde, benzene and trichloroethylene removal. Also noted for high transpiration rates.

Rubber plant (Ficus robusta) – Excels at formaldehyde removal.

Dracaena Janet Craig (Dracaena deremensis) – Excels at formaldehyde removal.

English Ivy (Hedera helix) – Excels at formaldehyde removal.

Dwarf date palm (Phoenix roebelenii) – Expecially recommended for xylene removal.

Ficus alii (Ficus macleilandii alii)

Peace lily (Spathiphyllum sp.) – Excellent for removing alcohols, acetone, formaldehyde, benzene and trichloroethylene.

Corn plant (Dracaena fragrans Massangeana) – Another good choice for formaldehyde.

Golden pothos (Epipremnum aureum)

Kimberly queen fern (Nephrolepis obliterata) – Good for formaldehyde and alcohols.

Florists mum (Chrysanthemum morifolium) – A good seasonal choice for formaldehyde, benzene and ammonia removal.

Gerbera daisy (Gerbera jamesonii) – Has a high transpiration rate.

Dracaena warneckei (Dracaena deremensis warneckei) – Excels at benzene removal.

Dragon tree (Dracaena marginata) – A top choice for xylene and trichloroethylene.

Schefflera (Brassaia actinophylla)

Spider plant (Chlorophytum comosum)

Weeping fig (Ficus benjamina)

For more information, we recommend reading How to Grow Fresh Air, 50 Houseplants that Purify Your Home or Office, by B.C. Wolverton.


Rev Environ Health, 33 (1), 63-76  2018 Mar 28

Antifungal Properties of Essential Oils for Improvement of Indoor Air Quality: A Review

Harriet Whiley 1, Sharyn Gaskin 2, Tiffany Schroder 1, Kirstin Ross 1

PMID: 29077554  DOI: 10.1515/reveh-2017-0023

Abstract

Concerns regarding indoor air quality, particularly the presence of fungi and moulds, are increasing. The potential for essential oils to reduce, control or remove fungi, is gaining interest as they are seen as a “natural” alternative to synthetic chemical fungicides. This review examines published research on essential oils as a method of fungal control in indoor environments. It was difficult to compare the relative performances of essential oils due to differences in research methods and reporting languages. In addition, there are limited studies that scale up laboratory results and assess the efficacy of essential oils within building environments. However, generally, there appears to be some evidence to support the essential oils clove oil, tea tree oil, oregano, thyme and lemon as potential antifungal agents. Essential oils from heartwood, marjoram, cinnamon, lemon basil, caraway, bay tree, fir, peppermint, pine, cedar leaf and manuka were identified in at least one study as having antifungal potential. Future studies should focus on comparing the effectiveness of these essential oils against a large number of fungal isolates from indoor environments. Studies will then need to focus on translating these results into realistic application methods, in actual buildings, and assess the potential for long-term antifungal persistence.