2026-08-13 · air

Tacoma fine particulate pollution runs above its usual range

Tacoma fine particulate pollution measured 14.5 micrograms per cubic metre on 2026-08-13, against a typical 7.5 across 31 comparable days (same time of year, all years on record), which ranged from 3.0 to 60.3.

Today

14.5

micrograms per cubic metre

Typical

7.5

median of 31 comparable days

Difference

+95%

against typical

Surprisal

2.4

bits

Tacoma fine particulate pollution, last 60 days on record. The dashed line is the median of the 31 comparable days used as a baseline (same time of year, all years on record), and the shaded band is one robust standard deviation either side of it. Those days ranged from 3.0 to 60.3. The marked point is 2026-08-13.

Quiet day. Nothing crossed the bar for a genuinely strange reading. This is the least ordinary thing the machine found among 20 series, and by chance alone a day like it turns up most days. Most days are ordinary. Saying so is part of the job.

Also unusual today

Seattle automatic fire alarms at 14 dispatches, typically 22 1.9 bits
Seattle lower-priority aid responses at 18 dispatches, typically 14 1.9 bits
Seattle motor vehicle incident calls at 10 dispatches, typically 6 1.9 bits
Wikipedia readers looking up the Tacoma Narrows Bridge at 158 pageviews, typically 198 1.6 bits

How this was measured

Series	`air.tacoma.pm25`
Value	14.5 micrograms per cubic metre
Baseline	median 7.5, range 3.0 to 60.3, from 31 days (same time of year, all years on record)
Robust z	+2.19
Surprisal	2.42 bits (p = 1.88e-01)
p estimate	empirical: measured directly against the comparable days
Series tested	20
Recurrence	most days

Read the full method, or take the permanent link to this day.

The headline and the sentence above were written by the machine from a fixed template. The language model was unavailable or its draft failed a check.