Particulate Matter
Particulate matter is tiny bits of dust, smoke, and soot that float in the air we breathe.
When you shake flour over a bowl, tiny bits float up into the air. Some are heavy enough to fall back down fast. Others are so light they drift around for a long time. Particulate matter works the same way in the air we breathe.
Explaining particulate matter by grade level
Dust and smoke float in the air all around us. Some bits are too small to see with your eyes. You can catch them on a sticky card left outside. Cards near busy roads collect more bits than cards in a park.
Projects that explore particulate matter
Heating systems pull air through filters constantly, and those filters slowly fill with particulate matter — the tiny bits of dust, smoke, and soot floating through indoor air. To find out which furnace filter brand catches more of these particles, you cut two brands in half and weigh each half on a triple beam balance. One half of brand A sits side by side with one half of brand B inside the same furnace for one week. When you remove and reweigh each half, the difference in mass tells you exactly how many particles each brand collected. After three to four repeated trials, brand A gained more mass every time — meaning it trapped more airborne particles under identical conditions.
Air pollution isn't the same everywhere — the amount of particulate matter drifting through the air shifts depending on location and even the day of the week. To measure this, you coat microscope slides with petroleum jelly and place them in different spots: some indoors, some outdoors on window ledges or in open fields. After leaving all slides exposed for the same amount of time, you compare them against control slides kept sealed in a drawer. Under a magnifying glass or microscope, you count the particles stuck to each one. The results show which locations collect the most airborne dust, smoke, and soot — and whether weekdays differ from weekends.
Particulate matter — tiny bits of dust, smoke, and soot — floats through the air and settles on sticky surfaces. You cover index cards with clear packing tape, sticky side out, and place them at different locations around a schoolyard. By comparing your cards to each other, you can figure out which spots have the poorest air quality.
Particulate matter — tiny bits of dust, smoke, and soot — fills the air in varying amounts across a city. Sticky collection boards left at eight urban locations for three days trap these airborne particles from the surrounding air. When you count the trapped particles per square centimeter, the bus station board has the most and the building rooftop has the fewest.