New research from Pennsylvania State University has found that each of us is regularly producing our own personal cloud of pollutants, which actually affects indoor air quality. Don't start sniggering and blaming the dog though – it's not the way you think. The team found that oils on our skin and clothes are reacting with ozone in the air, producing a range of volatile and semi-volatile substances.

While ozone is generally thought of as a good gas, that's only when it's high in the stratosphere, protecting us from the Sun's radiation. In high enough concentrations at ground level it can be harmful to breathe, irritating the airways and aggravating asthmatic symptoms.

Ozone is increasingly common in cities, where levels can vary between 5 and 25 parts per billion, or even higher, so the Penn State team set out to investigate indoor air quality, and found some rather surprising results.

"The bottom line is that we, humans, spend more than 90 percent of our time in buildings, or indoor environments, but, as far as actual research goes, there are still a lot of unknowns about what's going on and what types of gases and particles we're exposed to in indoor environments," says Donghyun Rim, an author of the study. "The things that we inhale, that we touch, that we interact with, many of those things are contributing to the chemical accumulations in our body and our health."

Using computer models of these indoor environments, the team found that ozone in the air can react with certain substances found in skin oils, such as squalene, fatty acids and wax esters. It turns out that these reactions can create substances such as carbonyls and other organic compounds, which in turn can further irritate the skin and lungs.

"When the ozone is depleted through human skin, we become the generator of the primary products, which can cause sensory irritations," says Rim. "Some people call this higher concentration of pollutants around the human body the personal cloud, or we call it the 'Pig-Pen Effect'."

That nickname for the effect comes courtesy of the smelly little Peanuts character Pig-Pen, who was always accompanied by his own personal cloud of dirt. Maybe he wasn't such an outcast after all.

Interestingly enough, the study showed that thanks to our skin oils we're actually reducing the levels of ozone in our immediate vicinity. And the longer we wear a particular piece of clothing without washing it, the more effective an ozone converter it becomes. A t-shirt saturated in skin oil, for example, can remove between 30 and 70 percent of the ozone circulating around the wearer.

But the researchers say it's hard to tell how well this positive is balanced out by the negatives – namely, the other pollutants in the personal cloud it creates. Instead, it's probably better to focus on cutting pollution and designing better indoor filtration systems.

The research was published in the journal Communications Chemistry.