Drought does or does not make air pollution worse; which is correct and why?

Rain influences air pollution. Wind does also. So, why wouldn’t drought? Seems logical it would.

I read where the effects of the drought in the western U.S., at least in the San Joaquin Valley of California, have made air pollution worse.

San Joaquin Valley Air Pollution Control District Executive Director and Air Pollution Control Officer Seyed Sadredin in the “A message from the Air Pollution Control Officer” section of the “Report to the Community: 2014-15 Edition” wrote: “As Valley residents, we are all painfully aware of the devastating impacts the drought has already had on our economy and the quality of life in Valley communities. Air quality was another victim of the unprecedented drought conditions we faced. Despite record low levels of particulate pollution emitted by Valley businesses and vehicles, these abnormal weather conditions led to extremely high levels of ambient particulate concentrations not seen in the Valley in over a decade.”

Seems straightforward enough, but how can one know for sure? Should location factor into any of this?

California’s San Joaquin Valley is known notoriously for its hot and, yes, dry summers. But, this is the way conditions typically are irrespective of whether it is a wet or dry year. To put things in perspective, in an average, normal year rainfall measures about 11.5 inches. In a really wet year, the Valley could get double that. In a really dry year, half a normal years’ rainfall would be about right. This year so far, total rainfall is nearly seven inches – 6.97 to be precise. Last year on this date, the total recorded rain reached only 4.81 inches. Rain for the year, meanwhile, is measured from Oct. 1 to Sept. 30. So, you can see this rain-year is winding down. California, incidentally, is in its fourth year of drought, that would be: 2011-’12, 2012-’13, 2013-’14 and 2014-’15.

So, if the drought does, in fact, make air pollution worse, this should show up in the number of days a year and/or during the summer months at least where the air quality being anything but good is greater during times of drought compared to times when precipitation totals are high – or one would think. The problem with reaching a conclusion based on that assumption is that many different variables would need to be taken into account as a lot more than just dry conditions could affect air quality. For example, a dry spell could be accompanied by strong winds which might help clean the affected air, the filth in it being blown elsewhere. Then again, the opposite could be true if the wind strength is strong enough to stir up plumes of dust, which would no doubt serve to worsen air quality. And, that is only one example.

What should prove helpful is to look at the overall trend in air quality during non-dry years to try to get a feel for what is going on air-quality-wise and compare this to the air quality trend in dry years.

As to the matter of location, this could definitely play into this as well. Not all areas in California, or, for that matter, throughout the west, register the same amount of non-good air quality days. There are regions where the air year-round is mostly clean while other areas may experience more non-good-air-quality days than good ones. So, in this sense location would be a factor irrespective of whether a particular region experiences drought conditions or it doesn’t.

If the proof really is in the pudding, as far as I’m concerned, before any entity can pronounce that drought conditions automatically result in poorer air quality, I would want to see firsthand proof. You know what they say: seeing is believing.

The end of the story? Hardly. After the rainfall season for this year officially ends on Sept. 30th, I will make it a point to take a look at fine particulate matter (PM 2.5) and ozone (O3) air-pollution data for every year going back to year 2008 to see if I am able to draw any sort of conclusion regarding whether or not the drought had an effect on air pollution in the San Joaquin Valley and report back with what I am able to find or not find.

Stay tuned.


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