With OMEGA® HHTP21, users can be proactive in measuring fine and course particulate pollution that comes from many different types of sources. Handheld unit offers measurement ranges of PM2.5 from 0–500 µg/m³, humidity from 1–99%, and temperature from -4 to 140°F. Meter includes Data Hold and Max/Min with time stamp function, 6-color LED indication of air quality at Good/Moderate/Poor, and preset warning point with buzzer alarm, LED, and alarm output.