Tropospheric ozone is a secondary pollutant, which means it’s produced by the action of sunlight on other pollutants. During the summer, and especially during heat waves, sunlight effect is maximum, and big quantities of tropospheric ozone are produced. Tropospheric ozone, which is a pollutant, mustn’t be confused with stratospheric ozone, which protects us from UV radiation, so it’s good for animals and plants. Tropospheric ozone is a powerful oxidant, and affects environment, people, plants, animals and materials due to this strong oxidant effect.

Sunlight makes some particles at the atmosphere (for example the ones coming from cars exhausts) react and produce ozone. This ozone remains at the atmosphere and it irritates respiratory tract by inhalation, and skin, eyes and membranes by direct contact. When temperatures are very high, our pets pant in order to reduce their body temperature, but since panting means breathing very quickly, they breathe a higher volume of ozone, and the damage is bigger. The effects are caused by the irritation, and include pneumonia, asthma crises, chronic bronchitis, coughing, and also ocular irritations with conjunctivitis. Where is ozone? The main problem with ozone is that it moves: traffic contamination is more important in towns, but the ozone produced when sunlight makes this traffic contamination react, appears and gets accumulated mostly in country areas. Besides, the effect of sea breeze makes ozone concentration get increased at midday and evening, and this is important, because we prefer to go for a walk with our dogs in the evening because temperatures are not so high, so they get exposed to this pollutant.
Some of the most important effects of heat waves are caused by high ozone concentrations rather than high temperatures themselves. Unfortunately there is nothing we can do for reducing ozone environmental concentrations, because regulations for reducing atmospheric pollutant emissions are a task for the authorities, but one thing we can do is to choose a less dangerous hour for taking our dogs for a walk.

Some extra info:

Liliana Aldeguer Cerdán col 793
English translation by Sergio Reina Esteban col 747