HazardsRiding in the smoke
ขี่ในควัน
Not a visibility problem first. A lungs problem first, and a visibility problem after.
What it is
In March and April the measured PM2.5 on this circuit sits above the US 24-hour standard on most days. On a bike you are breathing hard, at volume, for six hours.
The long version
The visibility part is real and is worst at the viewpoints, which are the places that were the reason for stopping. A ridge that should show fifty kilometres shows two.
The breathing part is the one that matters. Inference — a rider at speed moves far more air through their lungs than someone walking, and an open-face helmet filters nothing at all. A fitted FFP2 or N95 worn under the helmet is what people use; a surgical mask, a buff or a bandana does not filter particles at this size. Anyone with asthma should treat March and April as a medical question and not a scheduling one.
There is also a third effect that gets missed: Inference — smoke flattens contrast, and flat contrast on a road whose whole difficulty is reading the next bend's radius is its own hazard. Slow down more than the visibility distance alone suggests.
Runs with
- storyThe smoke — The four years of measurements behind this.
- eventBurning season — The dates.
- termPM2.5 — What is actually in the air.
Named here by
- coffeeThe 7-Eleven — Clean air indoors, when there is none outside.
- eventBurning season — What it does to you on the bike.
- termPM2.5 — What it does on a bike.
- storyThe smoke — Riding in it: what it does to sight and to lungs.
Where each claim comes from
| Field | Tier | Source | Note |
|---|---|---|---|
| default | harvested | Open-Meteo Air Quality API (Copernicus CAMS) — Open-Meteo | |
| text.story | inference | the mask and exertion reasoning is this project's; no clinical source is cited and none should be read in | |
| text_th | inference | written in Thai by this project, not machine-translated |
Sources
- Open-Meteo Air Quality API (Copernicus CAMS) — Open-Meteo
- Final Reconsideration of the National Ambient Air Quality Standards for Particulate Matter — US Environmental Protection Agency
- Southeast Asian haze — Wikipedia (en)
- Motorcycle helmet — Wikipedia (en)
cited Cited — a named source, linked · harvested Harvested — fetched from an open dataset, with its licence · tradition Tradition — general knowledge of the tradition, hedged · inference Inference — this project's own reasoning from the above · field Field — someone stood there