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Pollutants

Smoke

Wood smoke is worse than cigarette smoke.

more toxins
more severe toxins - dioxins.
longer lasting free radicals.

Allergens

The period at the end of this sentence is approximately 400 microns in size.
Pollen grains are 30 microns, dust mite waste particles are about 20 microns, and cat allergen particles vary from about 1 to 20 microns in size.
Virus .1 micron. Bacteria .5 micron.

Particulate matter

Size
- Common measurements: PM2.5 (2.5 micrometers), PM10 (10 micrometers)
- “It is generally recognized that smaller particles are more harmful to human health. Unlike larger particles, PM0.1 can penetrate pulmonary tissue, enter the bloodstream, and circulate throughout the body. Thereby, PM0.1 can damage a number of internal systems that may be inaccessible to larger particles.”
Measurement
- Units: μg/m³, AQI
  - For conversions: airnow calculator
- Instruments:
  - Can purchase USB charging censors which talk to phone apps quite cheaply.
Healthy levels
- Indoor 24-Hour PM2.5 levels 55.5μg/m³ = 150 AQI or above : unhealthy for all. Sensitive groups get affected at lower levels (> 35.5μg/m³ = 100 AQI).
- For outdoors, 24-Hour averaging is not that reliable - winds have a big effect.

Sources

Dust from sweeping on concrete yard in Mountain view raised PM2.5 levels from 20μg/m3 to 148 μg/m3.