How Do Heatwaves Affect Ozone?

It’s rare that the UK climate enjoys (or suffers, depending on your predilection) a heatwave, but when it does arrive, most of us are too busy topping up our tans or slapping on the sunscreen to worry about health repercussions beyond our skin. Indeed, the effect that elevated temperatures can have on the air we breathe goes all but unnoticed.

However, it’s vital to remember that ozone levels in our atmosphere are directly affected by the temperature. When heatwaves strike, this deadly pollutant can spike, causing subtle but potentially disastrous long-term impacts on our health. With that mind, exercising caution should be advised when spending time outdoors this summer.

What is ozone?

When most people hear the word “ozone”, they immediately think of the body of gases in our upper atmosphere which protects the Earth from the damaging rays of the sun. However, ozone also occurs closer to the surface of the planet, where it can be a cause for concern when it comes to air pollution.

The gas is formed when other particles of pollution, including nitrous oxides (NOx) and volatile organic compounds (VOCs), are exposed to strong sunlight. These contaminants are often detected in high concentrations around energy facilities and in places with a high volume of vehicular traffic, and are damaging in their own right. At elevated temperatures they can be converted into ozone, which is why heatwaves are so bad for air quality.

“Like most chemical reactions, that chemical reaction [of converting NOx and VOCs into ozone] comes faster in warmer temperatures,” explains meteorologist Jeff Masters. “So you’re going to crank out the ozone the hotter the temperature is
. That’s why ozone is a summer problem.”

The harmful effects of too much ozone

 According to the National Institute for Occupational Health and Safety (NIOSH), the recommended “safe” level of ozone exposure is a mere 0.1 parts per million (ppm). However, it is estimated that concentrations lower than this – 0.07 ppm, for example – can be enough to cause our lung muscles to tighten unnaturally, thus increasing the likelihood they may contract an infection.

 Ozone is also known to exacerbate the symptoms of asthma, cause chest pains, inflame tissue in the lungs and result in uncontrollable fits of coughing. As such, it’s a pollutant that’s well worth avoiding for the entirety of the population, but especially for vulnerable people. That includes the very young, the very old and those who already suffer from existing lung or cardiovascular conditions.

How can you limit your exposure to ozone during Britain’s excellent weather? The short answer is simple: stay away from pollution hotspots. It’s quite possible to still get your fill of vitamin C this summer – just try to do it in a quiet country park rather than by a busy urban thoroughfare.