STEM与日常科技·英语30篇（1）

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PM2.5传感器如何测量细颗粒物

PM2.5 sensors detect airborne particles smaller than 2.5 micrometers—about 1/30 the width of a human hair.
Most consumer-grade sensors use laser scattering: a laser beam shines through an air sample and hits suspended particles.
When light scatters off particles, a photodetector measures intensity and angle to estimate particle count and size distribution.
Algorithms then convert raw signals into micrograms per cubic meter (μg/m³), the standard air quality unit.
Calibration against reference lab instruments ensures accuracy, though low-cost sensors may drift over time.
Temperature, humidity, and airflow affect readings, so advanced models include environmental compensation.
Some sensors also distinguish between dust, smoke, and pollen using multi-wavelength lasers or optical filters.
Data streams wirelessly to apps, helping users decide when to run air purifiers or avoid outdoor exercise.
Citizen science networks now aggregate millions of sensor readings to map hyperlocal pollution hotspots.
Understanding these principles helps people interpret real-time air quality data more critically.