Could changing school schedule improve air quality, benefit students?

For two consecutive winters (2013-’14 and 2014-’15) in the San Joaquin Valley, air quality has been quite problematic. In Nov. and Dec. 2013, and in Jan. 2014 and Jan. 2015, many were the number of days where fine particulate levels exceeded the federal PM 2.5 daily standard of 35 micrograms per cubic meter of air.

Fireplace_Burning[1]Meanwhile, the San Joaquin Valley Air Pollution Control District (air district) stresses that as much as 30 percent of all fine particulate matter daily in Valley air in winter, is on account of residential wood-burning activity. 1

Yet, at the same time, in the air district’s “Report to the Community – 2014-15 Edition,” on page 51 there is a pie chart for “Annual PM 2.5 Emissions” and the breakdown is as follows:

  • Agricultural Waste Burning and Forest Management – 19%
  • Cooking Including Charbroiling – 5%
  • Farming Operations – 19%
  • Fireplaces and Wood Stoves – 6%
  • Fugitive Windblown Dust – 10%
  • Heavy Duty Diesel Trucks – 4%
  • Other Mobile Sources – 10%
  • Other Sources – 19%
  • Road Dust – 19%

As it has to do with the number of fine particulate matter exceedances in the Valley, in “Valley top spot for fine particle pollution … again!” I wrote: “… from the California Environmental Protection Agency Air Resources Board’s ‘Air Quality and Meteorological Information (AQMIS2)’ page, 49 is the number of days the Valley exceeded the 24-hour federal PM 2.5 health standard of 35 micrograms per cubic meter of air this winter (30 in Jan. and Feb. 2015 and 19 in Nov. and Dec. 2014), this compared with the South Coast Air Basin’s 25 (20 in Jan. and Feb. 2015 and 5 in Nov. and Dec. 2014). The number of times the Valley exceeded the federal PM 2.5 standard last year (Nov. 1, 2013 through Feb. 28, 2014) was 71.” The three months of the year where the greatest number of such exceedances appears to be occurring, are in Nov., Dec. and Jan.

Furthermore, between 1999-’00 and 2013-’14, season average PM 2.5 in micrograms per cubic meter ranged from a high of 44 in 1999-’00 to a low of 21 in 2012-’13. Average fine particulate matter in the Valley in 2013-’14, meanwhile, was 32 micrograms per cubic meter of air. For all years together during that 15-year span, average PM 2.5 is 30 micrograms per cubic meter of air.2

This time coincides with wood-burning prohibitions that go into effect in the Valley between Nov. 1 and Feb. 28. This past winter fine particulate matter levels reached as high as 144 micrograms per cubic meter of air on Nov. 7, 2014 in the city of Madera (this was more than four times the federal daily PM 2.5 health standard of 35 micrograms), and that was at 12 noon – a “ROAR” level of 5, incidentally. “ROAR,” according to the air district, stands for “Real-Time Outdoor Activity Risk.”

During winter, oftentimes the highest fine particulate matter concentrations are right around the noontime hour. In light of this would it behoove school district officials to create a school schedule taking into consideration these air quality conditions? For instance, school could be held from February to November.

Some might argue, however, that ozone levels are problematic during summer months. Though this may be the case, many agree that between ozone and fine particulate matter, the latter is by far the more unhealthful of the two pollutants.

Also, by adhering to this scheduling arrangement, summer school sessions would need to be rescheduled for winter.

There is no doubt something along these lines could work, but the main considerations are if student exposure level to fine particulate matter would be less, if summertime air quality would be appreciably worse, if the overall change would be more or less unhealthful for students and if air overall would improve as a result.

Barring implementing something on this order, subscribing to the traditional school schedule and scheduling time away from school on occasions when both fine particulate matter and ozone are at their highest concentrations typically, could provide a reasonable alternative to the earlier mentioned suggestion.

In the final analysis, some may be inclined to want to leave things well enough alone. On the other hand, such a readjustment potentially could be advantageous.


  1. “2013-2014 Wood Burning Season Summary,” from the San Joaquin Valley Air Pollution Control District Governing Board, Apr. 17, 2014, p. 4.
  2. Ibid, p. 9


– Alan Kandel

1 thought on “Could changing school schedule improve air quality, benefit students?”

  1. Alan,

    Reporting winter day sources of PM2.5 (2nd paragraph) and comparing these to annual average day sources (3rd paragraph) is akin to an apple and oranges comparison. Residential wood combustion occurs almost exclusively on winter days while agricultural waste and forest management (open) burning occur almost exclusively on spring, summer, and fall days. Thus, an annual inventory showing high contributions from open burning may confuse readers when they are asked to reduce wood heating during the high PM2.5 season, which extends from November through February as you report above.

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