Bushfires have been burning across many parts of Australia in recent weeks, particularly in the most populated state of New South Wales, and more recently Victoria. Catastrophic fire conditions have existed, with flames being fanned across the country by high winds, above 40°C temperatures, low humidity and long-term dryness in the bush. These fires are unprecedented and deadly, and many lives and homes have been lost. An area bigger than Belgium has already been burned, despite the warmest summer months not yet arrived.
The frequency and severity of bushfires in Australia will continue to increase with global warming, as they also will in New Zealand, California and other parts of the world.
Australian bushfires tend to burn for weeks on end across large areas of land, and this often sends smoke over populated areas. Residents of Sydney have endured smoke for weeks, and when I stood on the tarmac of Sydney airport recently, it was impossible to avoid the smokey smell despite official announcements saying there was nothing to worry about. Also the haze that seemed to envelop the whole city as the plane came in to land, causing poor visibility and making driving a dangerous pursuit. Millions of people in Sydney and other parts of N.S.W. and Australia, have been blanketed by and frequently exposed to bushfire smoke in recent weeks.
Effects on lung health:
Exposure to smoke is obviously not good for human or animal health, and the links between cigarette smoking, lung cancer and emphysema, are well established.
Harmful gases in smoke from burning bush include carbon monoxide, carbon dioxide and nitrogen oxide, all of which are present in cigarette smoke and more prevalent nearer to a fire. However, most danger lies in ultrafine particles known and measured globally as particulate matter PM2.5 (smaller than 2.5 micrometres in diameter). These are invisible to the human eye, cause haziness in the air and can travel vast distances on the wind. They are often coated in toxic chemicals such as lead, and are most worrying because their tiny size means they are able to penetrate deep into the lungs.
Recent PM2.5 readings in Sydney have reported levels as high as 734 micrograms – the equivalent of smoking about 37 cigarettes a day. Firefighters and those living closer to blazes, have been and are being exposed to much higher levels, according to a director of the Fire Centre Research Hub at the University of Tasmania, Prof David Bowman (1).
Australian Paramedics have treated hundreds of people for breathing problems, and there have been increased hospital admissions for asthma and breathing difficulties. Most sensitive are children, the elderly and smokers, while those with asthma, heart and lung problems have experienced increased symptoms such as chest tightness and difficulty breathing. If the smoke lingers, then harmful gases and PM2.5 particles could eventually have the same damaging effects on the lungs as cigarettes.
These types of exposures of millions of people to smoke inhalation from bush or forest fires, is clearly already a major public health concern. However, as with most health concerns, individual action and responsibility, also belongs to each of us.
So what can Australians and anyone else subject to significant or chronic exposure to smoke from bush or industrial fires do to reduce the harmful effects of this to their health, apart from stay indoors with the windows shut, wear masks that experts say do little to prevent fine particle inhalation, or simply panic?
Like most people I am angry and concerned about climate change, and don’t have many answers to offer. However, the impact that these bushfires are having on the Australian people is absolutely enormous, and it is therefore appropriate to review evidence suggesting that certain plant extracts may be usefully taken or inhaled by those forced to incur either acute or longer term ongoing exposure to smoke.
I’ve previously mentioned some of these in my September 2016 and November 2018 blogs in relation to the Haze season in Singapore, and high levels of airborne pollution in downtown Auckland. They include the herbs Marshmallow, Mullein, Elecampane, White horehound, Horseradish, Nasturtium, Ribwort, Hyssop and the New Zealand native plant Hoheria. In this and the next couple of blogs, I will further explore the relevant traditional use and pharmacology of each of these herbs in more detail, as being potentially useful when inhaled or ingested to help protect our lungs and overall health against the numerous damaging effects of bushfire smoke and other airborne pollutants.
Expectorants & mucous membrane tonics:
With smokers and others exposed to airborne pollutants on a regular basis, a cough is the body’s natural reflex to expel unwanted substances from the lungs. Critical to the lungs defence system, are the millions of tiny hairlike structures known as cilia lining our lungs, which beat in waves and whose natural function is to expel mucus and potentially harmful particles or gases. In medicine, expectorants are drugs and herbal preparations which have the ability to speed up and enhance this natural elimination and protective process, and their inclusion in most cough medicines, is well known.
Marshmallow (Althaea officinalis) root is no longer included in marshmallow confectionary products sold today, but this plant is still commonly used as an expectorant and for bronchial congestion, by herbal practitioners. Good quality marshmallow root contains at least 5-10% of mucilaginous polysaccharides (known as ‘mucilages’ to most herbalists), which form a protective and soothing layer on inflamed or damaged mucous membranes and human epithelia (2). German researchers have measured an increase in cell viability, cell vitality and proliferation, following treatment of human naso-pharyngeal epithelial cells with marshmallow extract (3).
Another useful mucilaginous herb regarded as a tonic for respiratory tract mucous membranes, is Ribwort (Plantago lanceolata). The leaves of this common plant when harvested and prepared in the optimal way and taken in sufficient doses, support the cilia’s protective barrier effects by nurturing the delicate mucous membranes of the upper nasal passage. Like Marshmallow and leaves or bark of the sweet tasting and mucilaginous New Zealand native plant Hoheria (Hoheria populnea), it has an expectorant and cleansing effect on the upper respiratory tract. These and other herbal expectorants, can thus be helpful, to help facilitate the bodies own natural defence system designed to keep harmful particles and gases, out of our lungs.
- Davey Melissa, Australia faces ‘massive’ rethink to prepare for long-term bushfires and air pollution. The Guardian, 15 Dec 2019.
- Schmidgall J et al, Int J Biol Macromolecules 10, 217-225, 2002.
- Deters A et al, J Ethnopharmacol 127(1):62-69, Jan 8, 2010.