Bushfires remain prevalent across Australia, with smoky conditions possibly becoming more normal as climate change takes hold. Rural communities in NSW have been inundated by smoke for weeks, with Sydney also choked by bad air and dangerous smoke particles. While everyone is aware of the destructive power of fire when it comes to harming property and affecting lives, the true dangers of bushfire smoke are only starting to be understood.

The air quality in Sydney has been ranked among the worst in the world over recent weeks, with air quality in the Harbour City worse than highly industrialised places like Shenzhen, China. Not only have we seen the highest levels of air pollution from smoke ever recorded, but health officials are warning of more stifling conditions to come. With bushfires continuing to degrade air quality for large parts of NSW, an increasing number of people are getting concerned about the impact on their own health.

The main harmful factor in bushfire smoke is the presence of minuscule solid particles, which can affect literally every aspect of human health. According to Associate Professor Fay Johnston, head of the environmental health group at the Menzies Institute for Medical Research, "These particles are classed as PM2.5, which means particulate matter less than 2.5 micrometres in diameter... Most of them are even smaller than that again, so we’re talking something really tiny, smaller than a red blood cell.”

While bushfire smoke has long been associated with asthma and breathing problems, there is an emerging consensus of links between bushfire smoke and increased risk of heart failure, heart attacks, strokes, pulmonary embolism, and high blood pressure. In fact, according to a US study on air pollution and human health, bad air quality is linked to increased hospital admissions for a much wider range of medical conditions than those usually blamed on pollution.

According to Professor Francesca Dominici in a study published in the British Medical Journal, air pollution was also connected to septicaemia, UTIs, and infection among other conditions: "Even though we don't know yet all of the clinical pathways that could have led to this disease [lung disease], we do know that inhalation of fine particulate matter penetrates deep into the lung and initiates a series of inflammations that could simultaneously affect multiple organs."

The bad news for Sydneysiders and others living under a smoky sky, is that summer has just begun. While recent conditions have been the result of unusual drought conditions and strong northerly winds, there is a very real danger that these events could become more normal. When conditions are really bad, it's best to avoid strenuous exercise and stay indoors. Face masks can also be useful in some conditions, but only if they're designed to filter 95% or more of tiny PM2.5 particles.