Particulate Matter Indicator

The Particulate Matter Indicator estimates the primary particulate matter emissions associated with Canadian agricultural activities from 1981 to 2011. Particulate matter is a mixture of solid particles and liquid droplets of varying size and chemical composition that are suspended in the air. It is classified as either primary particles emitted directly into the air or as secondary particles formed in the air by chemical or physical processes.

What are Agri-Environmental Indicators?

Agri-Environmental Indicators (AEI) are measures of key environmental conditions, risks, and changes resulting from agriculture and of the management practices that producers use to mitigate these risks. They help explain:

  • how the agriculture sector is performing,
  • why it is performing as it is,
  • whether that performance is satisfactory, and
  • how it is likely to evolve in the future.

Agriculture and Agri-Food Canada (AAFC) has been compiling and analyzing data and reporting on AEIs since 1993, but uses data from as far back as 1981. The Particulate Matter Indicator is one of several national indicators being tracked by AAFC.

Overall state and trend

Particulate matter emissions have been decreasing on agricultural lands in Canada, with a decline of 63% for total suspended particulate (TSP), 58% for PM10 and 61% for PM2.5 since 1981 (refer to Figure 1 below in the text box "What do the different size classes of particulate matter represent?" for an explanation of size classes). In 2011, emissions were 3,066 kilotonnes (kt) for TSP, 1,190 kt for PM10 and 276 kt for PM2.5. The greatest improvements have occurred in the Prairie Provinces and can mainly be attributed to a reduction in summerfallow, along with a shift to reduced tillage and no-till practices in this region, which has reduced the quantity of particulates produced during land preparation and harvesting.

What do the different size classes of particulate matter represent?

Particulate matter is comprised of millions of different chemical compounds, dust and biological material, including feather fibres, dander and bacteria. These particles are classified according to their aerodynamic diameter (which is a means of measuring their size as they have irregular shapes). They are defined as follows:

Particles with an aerodynamic diameter of less than 2.5 micrometres. These particles are easily inhaled into the lower airways (the gas-exchange regions of the lungs) and deposited in the lungs, causing adverse health effects.
Particles with an aerodynamic diameter of less than 10 micrometres, including PM2.5. These particles can be inhaled into and settle in the bronchi and lungs, leading to health problems.
Total suspended particulates consist of all particulate matter suspended in the atmosphere with an aerodynamic diameter of less than 100 micrometres.
Figure 1: Particle matter size classes – adapted from the United States Environmental Protection Agency (2004)
Description of this image follows.
Description - Figure 1

The diagram uses a human hair, between 50 and 70 micrometres in diameter to illustrate the particulate matter size classes.

TSP corn pollen up to 120 micrometres in diameter

PM10 Dust, mould, etc. less than 10 micrometres in diameter

PM2.5 combustion particles, organic compounds, metals, etc. less than 2.5 micrometres in diameter

Use the interactive map below to zoom in and explore different regions.  Note that the regions showing the highest emission levels are found within the Prairies, and both the Lake Erie Lowland region of southeast Ontario and the Saint Lawrence Lowlands region of Quebec contain some pockets of very high emissions.

In addition to exploring the 2011 values, click the play button to view changes over time. Since 1981, there has been a significant decrease in emissions across Canada, particularly evident across the Prairies, as well as in parts of Ontario and Quebec. Pockets of decline can be seen in southern BC and in parts of Quebec, as well as in the Maritimes.

Generally speaking, the large improvements in the Prairies can be mainly attributed to the reduction in summerfallow – a practice of leaving fields bare – as well as an increase in reduced tillage and no-till practices, which have reduced the amount of bare soil exposed to degradation and therefore the quantity of particulates produced during land preparation and harvesting. The isolated increases in emissions elsewhere can be explained by shifts in cropping practices and crop types. The sharp decline in beef cattle production between 2006 and 2011, as well as a longer-term decline in dairy herds since 1981, has reduced the area under pasture and forage production. Much of the area previously dedicated to these land uses has been converted to annual crops, such as corn, which do not provide as much cover as perennial crops, and increase the risk of particulate matter emissions during land preparation and harvesting. In spite of this however, overall trends are improving on a national basis.

Figure 2: Total suspended particulate emissions in Canada, 1981-2011

Legend: legend

Use the interactive map in Figure 3 to explore the change in total suspended particulate between 1981 and 2011. It is apparent that the decrease in particulate matter emissions is most significant in the Canadian Prairies.

Figure 3: Change in Total Suspended Particulate, 1981 to 2011

Legend: legend

Particulate Matter performance index

The state and trend of the Particulate Matter Indicator can also be seen in the performance index below.

Figure 4: Particulate Matter Index
Description of this image follows.
Description - Figure 4
Year Index Value
1981 17
1986 22
1991 23
1996 24
2001 33
2006 39
2011 50

In 2011, the state of particulate matter emissions resulting from farming activities in Canada was "Moderate". The index illustrates an improving trend, representing a reduction in particulate matter emissions between 1981 and 2011. This reduction is primarily attributed to the widespread adoption of reduced tillage and no-till, as well as decreases in the use of summerfallow in Manitoba, Saskatchewan and Alberta.

The index tends to aggregate and generalize trends and so should be viewed as a policy tool to give a general overview of state and trend over time.

How performance indices are calculated

Specific trends

Prairie farmland sees a significant reduction in particulate matter since 1981

The Prairie Region has seen significant reductions in particulate matter emissions over the past 30 years. While there are still pockets of high or very high emissions, much of the agricultural land within the Prairie Provinces has moved into a lower emission class category. You can explore these improvements in the swipe map below.

Figure 5: Change in total suspended particulate emissions (kg ha-1 yr-1) in the Prairies between 1981 and 2011.

Legend: legend

These reductions can also be seen in the table below, which reports in actual emissions, measured in kilotonnes per year. The most dramatic reductions in emissions have occurred in Alberta and Saskatchewan. Due to the large area of agricultural land in these two provinces, these improvements have strongly influenced the national trend of improvement, although all provinces demonstrated some improvement.

Table 1a: Total particulate matter emissions (in kilotonnes per year) from Canadian farms, 1981 to 2011

TSP Emissions (kt yr-1)
1981 1986 1991 1996 2001 2006 2011
*The Atlantic Provinces include New Brunswick, Nova Scotia, Prince Edward Island and Newfoundland and Labrador
British Columbia 29 28 27 25 24 23 19
Alberta 2,053 1,962 1,779 1,527 1,253 1,027 777
Saskatchewan 4,672 4,148 3,676 3,137 2,775 2,079 1,518
Manitoba 772 675 611 542 497 418 368
Ontario 643 565 542 488 490 255 232
Quebec 161 171 179 193 243 129 130
Atlantic Provinces* 29 26 25 26 27 23 21
Canada 8,360 7,575 6,840 5,938 5,308 3,954 3,066

Table 1b: PM10 emissions (in kt yr-1) from Canadian agricultural operations, 1981 to 2011

PM10 Emissions (kt yr-1)
1981 1986 1991 1996 2001 2006 2011
*The Atlantic Provinces include New Brunswick, Nova Scotia, Prince Edward Island and Newfoundland and Labrador
British Columbia 8 8 8 8 6 7 5
Alberta 712 688 632 588 474 412 325
Saskatchewan 1,707 1,529 1,357 1,248 1,107 883 647
Manitoba 255 230 210 202 173 152 131
Ontario 89 84 81 71 61 57 49
Quebec 25 24 24 26 27 26 26
Atlantic Provinces* 7 7 7 7 6 6 5
Canada 2,803 2,571 2,319 2,150 1,856 1,543 1,190

Table 1c: PM2.5 emissions (in kt yr-1) from Canadian agricultural operations, 1981 to 2011

PM2.5 emissions (in kt yr-1)
1981 1986 1991 1996 2001 2006 2011
*The Atlantic Provinces include New Brunswick, Nova Scotia, Prince Edward Island and Newfoundland and Labrador
British Columbia 2 2 2 2 2 2 1
Alberta 184 176 159 144 110 90 68
Saskatchewan 409 364 322 286 243 184 139
Manitoba 67 61 54 52 50 43 37
Ontario 32 31 30 26 23 21 18
Quebec 9 9 9 9 11 10 10
Atlantic Provinces* 3 2 2 2 2 2 2
Canada 707 644 578 522 441 353 276

Reason for this trend

The primary reason for the improvement in this indicator in Canada is the shift away from practices which leave the soils vulnerable to losses from wind erosion, such as summerfallow and intensive tillage. Wind erosion generates about half of the total particulate matter emissions in Canada, and soils are particularly at risk during land preparation. Figure 6 shows the change in percentage of farmland between 1981 and 2011 under summerfallow, under no-till for the Prairies (Alberta, Saskatchewan and Manitoba), and for Canada as a whole. Because the Prairie Region accounts for over 85% of farmland in Canada, changes in these provinces significantly impact the national averages.

Figure 6: Trends in summerfallow and no-till in the Prairies, 1981 to 2011.
(Note that Census data for tillage practices are available from 1991 onwards only).
Description of this image follows.
Description - Figure 6
Percentage of farmland under no-till
1981 1986 1991 1996 2001 2006 2011
Manitoba 5 9 13 21 24
Saskatchewan 10 22 39 60 70
Alberta 3 10 28 48 65
Canada 7 16 30 46 562
Percentage of farmland under summerfallow
1981 1986 1991 1996 2001 2006 2011
Manitoba 8 7 4 4 3 2 1
Saskatchewan 26 20 20 16 11 8 5
Alberta 12 10 8 7 6 4 2
Canada 14 12 11 9 6 4 3

Why this indicator matters

Particulate matter is recognized as an air pollutant that decreases visibility; contributes to stratospheric ozone depletion, acid rain and smog; and influences climate by altering both the amount of solar energy reaching the earth's surface and the amount of energy radiating back into space.

Agriculture has long been recognized as a significant contributor of atmospheric particulate matter emissions. Primary particulate emissions (particles released intact into the air) result from processes such as wind erosion and tillage (soil dust), burning (soot), crop harvesting and grain handling (grain dust). Ammonia emissions are the main agricultural source of secondary particulate matter (i.e. those particles that are formed in the air). Figure 7 shows the main sources of particulate matter.

Figure 7: Main activities and factors contributing to primary and secondary particulate matter (PM) emissions in agriculture
Description of this image follows.
Description - Figure 7

The graphic illustrates the on-farm sources of particulate matter and the size of particulate matter associated with each. The following activities and factors generate all three sizes of particulate matter (TSP, PM10 emissions and PM2.5 emissions): wind erosion; land preparation; crop harvest and grain handling, agrochemical and manure application; and animal feeding. Residue burning and animal cremation generates PM2.5 emissions. In addition, the following activities generate chemicals that are precursors to secondary particulate matter: animal feeding (which generates ammonium – NH3); some types of crop produce biological volatile organic compounds (VOCs); and soils can generate nitric oxide (NO).

Agriculture has the potential to mitigate particulate matter emissions by implementing beneficial management practices.

Beneficial management practices

In the Prairies especially, those practices recommended for the prevention of soil erosion can lower particulate matter emissions. These include reducing summerfallow and tillage intensity and by increasing soil cover on cropland. Other options include increasing the area of permanent grassland; using forages in rotations; growing winter cover crops; and using strip cropping, contour cultivation and windbreaks.

Primary particulate matter can also be emitted from animal feeding operations such as barns or on feedlots. Emissions can be reduced by decreasing animals' confinement time (or increasing the grazing period), collecting litter and manure more frequently, installing dust extraction or filtered ventilation systems, and sprinkling water mist or oil onto the floor or ground surface to reduce dust.

How performance indices are calculated

The agri-environmental performance index shows environmental performance state and trends over time, based on weighting the percentage of agricultural land in each indicator class, such that the index ranges from 0 (all land in the most undesirable category) to 100 (all land in the most desirable category). The equation is simply "(% in poor class multiplied by .25) plus (% in moderate class multiplied by .5) plus (% in good class multiplied by .75) plus (% in desired class)." As the percentage of land in the "at risk" class is multiplied by zero, it is not included in the algorithm.

The table below shows the index classes. The index uses the same five-colour scheme as the indicator maps whereby dark green represents a desirable or healthy state and red represents least desirable or least healthy.

The index classes
Scale Colour scheme Class
80-100 Dark green Desired
60-79 Light green Good
40-59 Yellow Moderate
20-39 Orange Poor
0-19 Red At risk

Related indicators

  • The Soil Erosion Indicator tracks the health of Canadian agricultural soils as it relates to the risk of erosion from tillage, water and wind.
  • The Soil Cover Indicator summarizes the effective number of days in a year that Canadian agricultural soils are protected by vegetation, crop residue or snow.
  • The Ammonia Indicator estimates the annual emissions of ammonia to the atmosphere from livestock production and fertilizer applications on Canadian farmland.

Additional resources and downloads

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