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