On Thurs., Jun. 18th, posted on the Air Quality Matters blog was: “High temperature, high pressure, high ozone and clear skies? Yes!”
With a title like that, it would seem that the air condition that existed in Fresno on Sun., Jun. 14th, was favorable when, in fact, it wasn’t. So, it could very well be that that post title was misleading. One adage more than any other comes to mind: A book cannot always be judged by its cover. Ah, but another: “Looks can be deceiving,” comes to mind here too.
True, area skies were clear. But another thing needs to made clear here: Clear skies alone do not always tell a person all that they need to know. Unfortunately, ozone was in area air that day at both moderately unhealthy and unhealthy levels. And, smog, often associated with ozone, it, on the other hand, was noticeably missing.
So, ozone, what is it, exactly?
Ozone (O3) is formed from the combination of hydrocarbons (HC) with oxides of nitrogen (NOx) in the presence of sunlight. It is naturally occurring in the stratosphere and is otherwise known as stratospheric ozone. But, on the Earth’s surface and close to it, what is often referred to as “ground-level ozone” or “tropospheric ozone,” this is the non-naturally occurring ozone – the unhealthy type that is damaging to lung tissue when breathed in.
It isn’t just this. Ozone as a corrosive gas is invisible. It can’t be seen by the naked eye, in other words.
Also important to know about O3 is that it appears to be unhealthy at even low concentrations. This is no doubt the reason for change being sought by the U.S. Environmental Protection Agency (EPA) to revise the 8-hour National Ambient Air Quality Standard (NAAQS) for both primary and secondary ozone from its current 75 parts per billion (ppb) of air concentration standard (set in 2008) to between 70 and 65 ppb.
From “Process of setting new smog standards shouldn’t be like pulling teeth” there is this:
“Remember: Anything over the 75 ppb threshold corresponds to an Air Quality Index (AQI) of 101 which means ‘unhealthy for sensitive individuals’ (or groups) or worse – either unhealthy for everyone (at best) or hazardous (at worst). With a new standard adopted this would more than likely mean the AQI would need to be adjusted to reflect the change.”
And, also from that same article, so noted is that “A final ruling is expected by October later this year.”
The lesson here is that ozone is something that needs to be paid careful attention as what cannot be seen – ozone in this case – can most assuredly be harmful. It is important to take heed.