Yet, nice as they can look, studies show burning candles is one of the . This is because when burning, candles emit a .
These particles are so small that they are invisible to the human eye, and more than a thousand times thinner than a human hair. They can remain airborne for long periods, and when candles are blown out, the concentration of these particles (including soot) increases even further.
conducted in exposure chambers (where the climate is controlled) at Aarhus University, we examined how indoor air is affected both by burning candles and cooking pork in an oven.
Cooking – and especially frying – is known to emit high concentrations of particles due to combustion (the process of burning something). Particles from combustion processes are among the to human health – but less is known about the role that particles emitted from candles plays when it comes to indoor air pollution.
Our research found that while both candles and cooking emit high levels of particles, the number . Even more significant was the difference in particle size: cooking produced particles about 80 nanometers wide, whereas candles generated particles around seven-to=eight nanometers in size – much smaller and much easier for our lungs to inhale.
We also measured chemical compounds in the air, and found that burning candles produced not only soot particles but gases such as nitrogen dioxide and polycyclic aromatic hydrocarbons (PAHs) – a group of chemicals associated with inflammation and even cancer.
Ultrafine particles are of particular concern from a health perspective. They are easily inhaled into our lungs, but has found they are excreted from the body very slowly.
Due to their extremely small size, particles from candles , known as the alveoli, and . From there, they can reach organs such as the heart and brain.
Indeed, the particles formed when candles are burning are remarkably similar to those found in diesel exhausts in . These particles have been to increased mortality rates from lung and cardiovascular diseases.
In our , we also investigated how candle burning affects young adults with mild asthma. We found subtle but measurable biological changes following exposure to candle emissions.
Some markers of airway and blood inflammation were altered, and participants . Other among healthy adults have observed small decreases in , changes in and heart rate, and after exposure to burning candles.
You might be thinking: all this from just a candle? But it’s worth remembering that people with chronic conditions like asthma or chronic obstructive pulmonary disease are far more sensitive to particulate air pollution.
Because people with these conditions already have chronically inflamed airways, even relatively low levels of pollution — including particles released by burning candles — can be enough to trigger symptoms.
Children, older adults and people with chronic illnesses are also particularly vulnerable to air pollution, due to immaturity of their lungs or weakened immune systems.
Indeed, for anyone with asthma or other respiratory conditions, the quality of indoor air is not a minor detail, but a key factor in day-to-day symptom control and long-term respiratory health.
But that’s not to say those without lung disease or asthma aren’t affected. As shows, burning candles affects not only the indoor environment but potentially everyone’s health. Fortunately, a few simple steps can help maintain a healthier indoor climate.
Try using LED candles, for example, or light only a few candles at once. You should also place candles away from drafts to avoid a flickering flame, which can produce more soot and smoke. Trim your candles’ wicks to reduce soot formation, too. And candles should never be burned near (or by) people with respiratory disease.
Most importantly, air out the room afterwards by opening your windows. Such measures can help reduce the number of particles significantly, and make all the difference when it comes to keeping your cosy or -time healthy.
, Postdoctoral fellow in Public Health,
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