STEM与日常科技·英语30篇（7）
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How Air Quality Monitors Detect PM2.5 Without Lab Equipment
空气质量监测仪如何无需实验室设备检测PM2.5颗粒
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Portable air quality monitors detect PM2.5 particles using laser scattering principles instead of lab-grade filters.
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A tiny laser beam shines through an air sample chamber where particles pass one by one.
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Each particle scatters light at angles that sensors measure to estimate its size and concentration.
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Algorithms compare scattering patterns against known standards for PM2.5, PM10, and pollen.
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Temperature and humidity sensors correct readings because moisture affects particle behavior.
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The device updates measurements every six seconds and averages them over ten minutes for stability.
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Battery-powered units use low-power processors to run these computations continuously.
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Manufacturers calibrate each unit against reference instruments before shipping to ensure accuracy.
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Consumer models trade some precision for affordability but still meet WHO guideline thresholds.
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This real-time insight helps people avoid exposure during wildfire smoke or traffic pollution peaks.