Science project

Counting Air Particulate Matter


Is There More Air Particulate Matter in an Urban or Rural Area?

I chose the problem "Is there more Air Particulate Matter in an Urban or Rural Area" because I was interested in finding out whether air pollution is different in an urban and rural area. Also, I wanted to find out whether there is a difference in particulate air pollution depending, on the type of community or habitat. I also want to find out if the amount of particulate air pollution in an area is constant over time, or are there other factors that affect it, like weather or human activity.

Air pollution is known to be a health hazard. I was interested in doing an experiment to find out some of the patterns of air pollution.

  • Is there a difference between air pollution in urban areas as compared to more rural areas?
  • In a setting (urban versus rural), is there a difference in air pollution within different communities?
  • Is the quantity of air pollution the same over time or does it vary with temperature, wind, or human activity?

I used a measure of particulate air pollution to answer some of these questions.

Background Information

Pollutants are any materials, such as gas, particles, or chemicals that are released into the environment. The class of pollutants that are released into the atmosphere is known as air pollutants and is called air pollution. Air pollution can be in gaseous or particulate forms. Major sources of air pollutants are from the burning of fuels and wastes, factory emissions, automobile exhaust, and cigarette smoke. There are natural sources of air pollution as well. For example, the dust and salt blown from the ocean or the "haze" produced by plants in our large forests are natural forms of air pollution.

The chief forms of chemical pollutants in air pollution are carbon dioxide (CO2), carbon monoxide (CO), volatile-organic compounds (VOC), nitrogen oxide (NOX), and sulfur oxide (SOX). These chemicals can mix together to form other chemical compounds that are also pollutants. These pollutants can have major effects on humans. Such as, a headache, itchy-red eyes, dizziness, tiredness, trouble breathing, colds, the flu, lung problems, even an increased death rate.

Another form of air pollution comes from particulate matter. It is called Particulate Air Pollution. This type of air pollution refers to microscopic, air-born particles, that are suspended in the atmosphere. Particulate matter is 10 microns or less in size. This is the same as one half of the width of an average human hair. Most sources of particulate air pollution come from organic sources. But most organic materials are not harmful. Some of the sources of particulate pollution in the atmosphere are from tobacco smoke, wood smoke, burning of coal, logging, earth moving (construction, road building), and diesel-burning vehicles. Even lawn mowers produce small particles when grass and leaves are chopped up and blown out from the mower. Particulate Air Pollution is a human health hazard because it can travel into your lungs and cause a variety of respiratory problems. Children and senior citizens are affected the most. Particulate matter can be cause an increase in emergency room visits, hospitalization, days off of school and work, heart and lung problems, and an increase death rate.

In addition to human health problems, both chemical and particulate air pollution are prime factors involved with the warming of the earth by the greenhouse effect and the depletion of the earth’s protective ozone layer. There are ways we can tell how bad the air pollution is around us.

The way we do this is with the "Air Quality Index"


I believe that there will be more air particulate matter in the urban areas than in the rural areas. From the background reading I learned that most of the sources of particulate matter come from urban areas. Automobiles and industry are the most common sources of particulate air pollution and there are more of both in urban areas as compared to rural areas.

I also hypothesize that within each area, the three different community types will have different quantities of particulate pollution. The road will have more than the fields, which will have more than the forests (roads > fields > forests). I believe this because there is more activity that produces particulate pollution near a road. In the fields there is air circulation, which will bring in particles but it is not near the sources of pollution. The forest will have the best air quality because the air is still and the tree’s leaves block particles.


  • 6 or more slides (3in-1in)
  • Permanent marker
  • Ruler
  • 3 sites in an urban area
  • Forest - Millstream Park
  • Field – Millstream Park * Road – Railroad Ave.
  • 3 sites in a rural area
  • Forest – Back yard, Deerfield
  • Field – Back yard, Deerfield
  • Road – Coon Box Rd.
  • Vaseline
  • Dissecting microscope


  1. Choose three similar sites in both an urban and rural area: along a major road, grass covered open area, and forest.
  2. Mark two equal areas (1.5 cm x 1.0 cm = 1.5 cm2) on the back of each slide with a permanent marker. Each 1.5 cm2 area constitutes a sample.
  3. Label one section of the slide A the other B. Make sure that all labeling is on the back of the slide, otherwise the sample areas and the labeling may be mistakenly rubbed off.
  4. Give each slide a number 1-6 and have a key for the area and place where the sample will be taken in. For example: #1-urban field, #2-urban road, etc.
  5. On the opposite side you marked on, apply a thin coating of Vaseline. Rub any excess off the slide to make the Vaseline coating even. (When particulate matter lands on the Vaseline it will stick to the slide.)
  6. In the three different areas lay the slide on a flat surface (fallen tree, block of wood, etc.) and in an open area.
  7. Leave the slides out for 24 hours to collect particulate matter.
  8. Record weather conditions for the 24-hour period; high and low temperature, wind velocity.
  9. Record any peculiar activity that may have occurred in the vicinity of a sample during the 24-hour period.
  10. Collect the samples and place them in a covered container so they are not contaminated with additional particulate material as you leave the site.
  11. Carefully, without smearing the Vaseline, take each slide and put them under a dissecting microscope.
  12. Under the microscope count the particulate matter in each of the 1.5 cm2 sample sections and record your observations.
  13. Repeat this procedure a minimum of three times per site.


My data show that there is more air pollution particles in the rural areas as compared to the urban areas (Table 1). When all of the samples in all of the communities were averaged together, the total particles for the rural areas averaged 153.40 particles/1.5 cm2 and the urban average was 134.07 particles/1.5 cm2 (Fig. 1). Looking at all the data from each one of the 3 trial taken, in every case the rural areas had a higher number of particles than when compared to the urban areas (Fig. 2). In the three trials the particles in the rural area were 445.5, 459.5, and 475.5 particles/1.5 cm2 and the three urban trials were 348.0, 424.5, and 453.0 particles/1.5 cm2 (Table 1). These findings are completely opposite my hypothesis where I thought that there would be less particulate pollution in the rural areas as compared to the urban areas.

I think that there are several reasons why my experiment produced these results. First, the samples were taken during the period of mid October to mid November. This was the finishing of the corn harvest and during the soybean harvest. Harvesting crops with a combine produces lots of dust and chopped up plants that are blown in the air. I think these particles were what landed on my slides. The urban areas are far enough away from the harvesting that the particles were not blown there. If I had done this test during the summer when there was no harvesting or when farmers are not working their fields, I think I would have different results. I also think that the particles that are produced in urban areas may be too small to be seen with a dissecting microscope. Particles of soot from car and truck exhaust are very small as compared to dust, soil particles, and plant parts that are blown in the air from harvesting.

One other hypothesis I had was that there would be a difference in the particulate air pollution in different types of habitats. My hypothesis was that there would be more particles in near the road and the least amount would be in the woods. I thought the field sites would be somewhere in between. The data for the rural areas (Fig. 3) show that the most particles were collected from the forest site and the least from the road site. This is completely opposite my hypothesis. I this is because the forest slows wind movement and allows particles to settle better than along the road or in a field.

Unlike the rural area, the urban area did agree with my hypothesis that the road would have the most particulate pollution (Fig. 4) when compared to other habitats. But the urban field did show the lowest amount of particles.


In conclusion, my project was to find out, "Is there more air particulate matter in an urban or a rural area". For my project I chose three sites in an urban area and three sites in rural area. Then I placed slides smeared with a thin layer of Vaseline in each of these sites to capture particulate air pollution. I repeated the experiment three times and averaged the results. Based on my date there was more air particulate matter in the rural area as compared to the urban area. This was because the time of the year I sampled was during the corn and soybean harvest and that produced a lot of material. I do not think that this level of particulate matter is constant throughout the year but does occur when farmers are active in their fields. Also, the soot particles produced by automobiles and trucks in the urban area may have been too small to see and count.

The data that I recorded was opposite my hypothesis in one case but not another. I thought there would be more particulate pollution along the road as compared to the field or the forest. In the rural area my hypothesis was wrong. But in the urban area it was correct. I think that forests slow the movement of air. In the rural areas where there was crop harvesting, the particulate matter settled out. But in the urban area where there was no plant particles to settle out in the forest, the road had the greatest amount of particulate air pollution.


  • Williams L. Ramsey, Lucretia A. Gabriel, James F. McGuirk, Clifford R. Phillips, Frank M. Watenpaugh, 1982, Holt Science textbook, Holt, Rinehart &Winton Publishing, pp. 472-477.
  • American Lung Association, The Air Quality Index - Fact Sheet.
  • protection
  • Boy Scouts of America, 1998. Environmental Science Merit Badge Handbook, Irving, TX, pp. 96.
  • Environmental Protection Agency (EPA) ( Air Quality Index, Fact Sheet.
  • EPA, (, Particulate Matter. * EPA, (, Air Now.
  • Miller, Tyler, 1988. Environmental Science, 2nd edition. Wadsworth Belmont CA, pp. 318-346.
  • Oregon Department of the Environment, (, Air Quality Index.





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