Why stay inside during an ozone alert?

[AskNott]

The Indianapolis area, and downwind counties, have an ozone alert today, which they call a Knowzone Day. When hot weather combines with a stationary front, the stuff from local pollution sources gives us more ozone than is safe for children and folks like me with breathing difficulties.

The Knowzone notices tell us to stay indoors, restrict motorized travel, and not mow or fill gas tanks until after 6:00pm. I don’t entirely understand this.

Isn’t ozone a gaseous form of oxygen that can’t be escaped by staying indoors? Do they just want to avoid having me do my coughing out in public?

[anson2995]

If I might add to the OP’s question…
Driving on the freeway yesterday, I noticed the messageboard said “High ozone levels. Please reduce speed.” How does driving slower help?

[Tapioca_Dextrin]

What is Ozone? Where does it come from?

Ozone is a toxic gas which is formed by a reaction between air pollutants and sunlight. 

While the ozone layer in the upper atmosphere protects you from the sun's most damaging rays, ozone near the ground is a health hazard. Ground-level ozone affects the respiratory system and can be especially harmful to the very young, the very old, and people with chronic lung disease. 

Although we have some control over pollutants, we have no control over the heat and sunlight that turn pollutants into ozone. Ozone is most likely to exceed safety limits from April through October (ozone season), when seasonal heat and sunlight are highest. 

In metropolitan areas, consumers are responsible for a significant percentage of the air pollutants that lead to smog. These pollutants come from our cars, lawn mowers, boats and the oil-based paints and cleaning products we use at home.

Driving faster makes your car less fuel efficient. Burning more gas = creating more pollution = creating more ozone.

Going outside means that you are going to drive somewhere, or you’re going to walk. Walk = exercise. Exercise = breathing more air. Breathing more air = breathing more pollution.

[AskNott]

@Tapioca Dextrin

Going outside means that you are going to drive somewhere, or you’re going to walk. Walk = exercise. Exercise = breathing more air. Breathing more air = breathing more pollution.

I routinely go to the gym to work out, indoors. They don’t warn against exertion, just going out, as if the air is better in here. Filters and air conditioning would seem to have no effect on ozone. I cut short my Thursday workout because I started to feel vaguely awful after about half an hour.

I have no problem staying in; it’s hot and muggy out there. I’ve not used the grill during the alert. I’m not doing much driving. I haven’t mowed since before the alert. However, the dog must be walked.

[clairobscur]

@AskNott

I routinely go to the gym to work out, indoors. They don’t warn against exertion, just going out, as if the air is better in here. .

Over here, they do advise against exertion, especially for kids, elders, people with respiratory issues, etc… during ozone alerts.

However, they also advise against going outdoors for the same categories of people. And I too wondered why. It’s not like ozone is going to avoid trespassing, is it?

[Broomstick]

As someone with some respiratory problems…

I can’t explain the why of it, but ozone+hot air+humidity is a lot harder for my lungs to handle than cooler air and less humid air, with or without ozone. So it may not be so much the quantity of ozone as removing the additional stressors of heat and humidity that makes the difference.