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Last Edited: 3/26/2015

Air Contaminants: Particulate Matter (PM)

Particulate matter (PM) pollution consists of solid and liquid particles in the air.  Fine particles known as PM10 and PM2.5 can penetrate deep into the lungs, creating health problems.  PM pollution is of large public health concern.  To learn more, scroll down or select from a topic below.


What is particulate matter and how does it get in the air?

Particulate matter (PM) pollution consists of solid and liquid particles in the air.  Particles can consist of materials such as dust, dirt, soot, smoke, salt, acids, and metals.  Particulate matter varies in size, and the smallest particles are of greatest health concern. 

  • Some particles are large or dark enough to be seen, such as soot or smoke
  • Other particles are so small you cannot see them
  • We often hear about two categories of PM smaller than 10 micrometers
    • PM2.5 Particles 2.5 micrometers and smaller are known as PM2.5
    • PM10 Particles less than 10 micrometers are known as PM10 -- this category includes PM2.5
  • Ten micrometers is about seven times thinner than one human hair
    • Particles less than 10 micrometers can be inhaled deep into your lungs
    • Particles bigger than 10 micrometers can irritate your eyes, nose and throat, but do not usually reach your lungs

Particulate matter pollution can cause problems in the environment. 

  • PM10 makes up a big part haze that we call smog
  • PM can be carried over long distances and end up on the ground or in the water
    • This can make rivers and lakes acidic and reduce nutrient levels in the soil
  • Particle pollution can also damage and stain stone, monuments and statues

Particulate matter comes from a variety of sources.  According to ARB, the major sources of PM10 in urban and rural areas include:

  • Motor vehicles
  • Wood burning stoves and fireplaces
  • Dust from construction, landfills, and agriculture
  • Wildfires and brush/waste burning
  • Industrial sources
  • Windblown dust from open lands

Particulate matter also forms when gases emitted from motor vehicles and industry undergo chemical reactions in the atmosphere. 

 

Particle pollution can be a problem at different times of year, depending on where you live.  The California Air Resources Board (ARB) has extensive information about particulate matter and other air contaminants on their website. 

 

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What are the health effects of particulate matter?

Short-term exposure to PM can affect people with heart or lung diseases.  If you have a heart or lung disease, being exposed to particle pollution for short periods of time like hours or a few days can:

  • Make lung disease worse
  • Cause asthma attacks
  • Cause bronchitis
  • Make it easier for people to get respiratory infections
  • Cause irregular heartbeat or heart attacks in people with heart disease

If you have heart disease and PM levels are high:

  • Coming in contact with particle pollution can cause serious problems in a short period of time- such as a heart attack- without any warning signs
  • Symptoms like chest pain or tightness, fast heartbeat, feeling out of breath, and feeling tired more than usual may be signs of a serious problem
    • If you have any of these problems, follow your doctor’s advice and contact your doctor if they last longer than usual or get worse

If you have lung disease and PM levels are high:

  • You may not be able to breathe as deeply or strongly as normal
  • You may cough more, have chest pain, wheeze, feel like you can’t catch your breath, and be tired more than usual
  • You should be sure to follow your asthma management plan if you have asthma

Short-term exposure to PM among pregnant women has been associated with prematurity and growth retardation.  Short-term exposure to PM has also been linked with premature death, usually in people who already have a serious health problem like lung or heart disease.  Healthy children and adults usually do not have serious problems from short-term exposure to particle pollution.  They may have minor problems like a scratchy throat or scratchy eyes when particle levels are elevated.

 

Long-term exposure has been associated with heart and lung problems.  Being exposed to particle pollution for more than a year is linked to problems like:

  • Breathing problems
  • Reduced lung function
  • Chronic bronchitis
  • Heart disease

These problems may lead to more hospital stays, more emergency department visits, and even premature death.  Sensitive people such as older adults, people with diseases like asthma or congestive heart disease, and children are more likely to be affected by contact with PM.

 

For more information, the California Air Resources Board has quantified the health impacts of exposure to air pollution in California, in particular for PM2.5 and ozone.

 

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Who is at risk?

People with heart or lung diseases, older adults, and children are most likely to have problems because of contact with particle pollution.  While particle pollution is a concern for everyone, the following groups of people are especially at risk.  They include:

  • People with heart and lung diseases
    • Particle pollution can make these diseases worse
  • Older adults
    • They may not know they have lung or heart disease
    • When particle levels are high, they are more likely to have to go to the hospital and may die exposure to particle pollution made their heart or lung disease worse
  • Children
    • They are still growing and spend more time at high activity levels
    • Coming in contact with particle pollution over a long period of time may cause problems as their lungs and airways are developing-- this will put them at risk for lowered lung function and other respiratory problems later in life
    • Kids are more likely to have asthma and other respiratory problems, which can be made worse when particle pollution is high
  • People with diabetes
    • They are more likely to have also have heart disease

However, even healthy people may have short-term problems from exposure to high levels of particle pollution.

 

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How to reduce exposure

When PM levels in the air are very high, everyone can reduce their exposure by:

  • Spending less time outdoors
  • Reducing physical activity levels (e.g. walking instead of running)

You can plan your daily activities to reduce exposure to PM.

  • Exercise away from roads and highways, especially if you are in a group at high risk of having health problems from particle pollution
  • Check the Air Quality Index (AQI) in your area
    • A list of regional air districts and links to current air quality data can be found here
    • Learn more about the Air Quality Index on the California Air Resources Board website
    • Local TV stations, radio programs, and newspapers report these air quality forecasts to tell you when particle levels are likely to be unhealthy
  • View Reducing Your Exposure to Particulate Pollutants (PDF) from the California Air Resources Board for more information

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Measures of particulate matter


The measures currently available on our air quality data query are:

Measures for PM2.5

Measures for PM10

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Percentage of days for daily PM2.5 average concentrations over the daily U.S. standard (35 µg/m3)

PM2.5 is monitored over a 24 hour basis.  Depending on location and season, this data is collected every one to six days.  The average of the 24 hour measurements in one day is the daily PM2.5 average concentration.  Where PM2.5 monitors exist in a county, we have calculated the percentage of days in a year in which the daily PM2.5 average concentrations exceed the U.S. standard (National Ambient Air Quality Standard or NAAQS) of 35 μg/m3


What does this measure tell us? 

    • This measure can be used to inform the public and policy makers regarding the frequency of potential exposures to PM2.5 during a year for counties with monitors

    • This measure can tell us how many monitored days per year county residents could potentially be exposed to unhealthy levels of PM2.5

    • This measure can be used to communicate to sensitive populations (such as asthmatics) the percentage of days that they may be exposed to unhealthy levels of PM2.5

What can’t this measure tell us?

    • This measure cannot tell us what levels populations in counties without monitors are exposed to

    • This measure does not provide information regarding the severity (or maximum concentrations) of potential exposures

See the latest results for this measure on our data query tool.


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Number of person-days for daily PM2.5 average concentrations over the daily U.S. standard (35 µg/m3)

This measure is an estimate of the number of people exposed to high daily PM2.5 concentrations in a county.  The measure is calculated by multiplying the number of days that monitored levels are above the U.S. standard in a given county and the population of that county.

What does this measure tell us? 

    • This measure can tell us which counties have the most people impacted by PM2.5

    • This measure can tell us which counties are most in need of prevention and control strategies

What can’t this measure tell us?

    • This measure does not identify the number of potentially vulnerable populations in each county, such as the elderly and children, who are at greater risk for ill effects from air pollution

See the latest results for this measure on our data query tool.


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Annual average (μg/m3) of PM2.5 levels

The average levels of PM2.5 from each monitor (weighted by the number of samples within a quarter) in a county is calculated for each year.  If there is more than one monitor per county, then the means are averaged.

What does this measure tell us? 

    • This measure can give an idea of which county residents are at risk for long-term exposure to PM2.5

    • This measure can be used to inform the public and policy makers about the degree of potential exposure to particle pollution within a county during a year and over time (trends)

What can’t this measure tell us?

    • This measure cannot tell us what populations in counties without monitors are exposed to

    • This measure does not provide information regarding the severity (or maximum concentrations) of potential exposures

See the latest results for this measure on our data query tool.

 

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Percentage of population living in counties with PM2.5 levels greater than the annual standard (12 µg/m3), less than the standard, and with no monitor

This measure is an estimate of the percentage of the state population living in counties with PM2.5 levels above the U.S. annual standard.  The measure also reports the percentage of people living in counties below the standard and the percentage of people living in counties with no monitor.

What does this measure tell us? 

    • This measure can give an idea of how many people in the state are at risk for long-term exposure to PM2.5

    • This measure can be used to inform the public and policy makers about the overall progress of the state toward protecting its population from long-term exposure to PM2.5, and can show change over time (trends)

 What can’t this measure tell us?

    • This measure cannot tell us what populations in counties without monitors are exposed to

    • This measure does not provide information regarding the severity (or maximum concentrations) of potential exposures

    • This measure does not identify the number of potentially vulnerable populations, such as the elderly and children, who are at greater risk for ill effects from air pollution

See the latest results for this measure on our data query tool.


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Estimated number of days for daily PM10 average concentrations over the CA standard (50 µg/m3) by air basin

PM10 is monitored over a 24 hour basis, primarily once every six days.  The average of the 24 hour measurements in one day is the daily PM10 average concentration.  The "Estimated Days Over the State 24-Hour PM10Standard" is the estimated number of days in the year that the California 24-hour  PM10 standard would have been exceeded had sampling occurred every day of the year. State PM10 statistics are based on local-conditions data.  Air Basins are multi-county regions of the state that have similar meteorological and geographic conditions. Air basins boundaries typically follow county boundaries, but there are several instances within the state where air basin boundaries fall within a county, dividing the county between two or more air basins (http://www.arb.ca.gov/desig/airbasins/airbasins.htm).


What does this measure tell us?

    • This measure can be used to inform the public and policy makers regarding the frequency of exposures to PM10 during a year for air basin with monitors

    • This measure can tell us on how many monitored days per year air basin residents could potentially be exposed to unhealthy levels of PM10

    • This measure can be used to communicate to sensitive populations (such as asthmatics) the number of days that they may be exposed to unhealthy levels of PM10

What can’t this measure tell us?

    • This measure does not provide information regarding the severity (or maximum concentrations) of potential exposures

See the latest results for this measure on our data query tool.


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Estimated number of days for daily PM10 average concentrations over the US standard (150 µg/m3) by air basin.

PM10 is monitored over a 24 hour basis, primarily once every six days.  The average of the 24 hour measurements in one day is the daily PM10 average concentration. The "Estimated Days Over the US 24-Hour PM10 Standard" is the estimated number of days in the year that the US 24-hour PM10 standard would have been exceeded had sampling occurred every day of the year. National PM10 statistics are based on local-conditions data. Air Basins are multi-county regions of the state that have similar meteorological and geographic conditions. Air basins boundaries typically follow county boundaries, but there are several instances within the state where air basin boundaries fall within a county, dividing the county between two or more air basins (http://www.arb.ca.gov/desig/airbasins/airbasins.htm).

              What does this measure tell us?

    • This measure can be used to inform the public and policy makers regarding the frequency of exposures to PM10 during a year for air basin with monitors

    • This measure can tell us on how many monitored days per year air basin residents could potentially be exposed to unhealthy levels of PM10

    • This measure can be used to communicate to sensitive populations (such as asthmatics) the number of days that they may be exposed to unhealthy levels of PM10

What can’t this measure tell us?

    • This measure does not provide information regarding the severity (or maximum concentrations) of potential exposures

See the latest results for this measure on our data query tool.


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Annual average (μg/m3) of PM10 concentrations by air basin

The average levels of PM10 from each monitor (weighted by the number of samples within a quarter) in a air basin is calculated for each year.  The "State Annual Average" for PM10 is the average of the year's quarterly averages of air basin monitors. Air Basins are multi-county regions of the state that have similar meteorological and geographic conditions. Air basins boundaries typically follow county boundaries, but there are several instances within the state where air basin boundaries fall within a county, dividing the county between two or more air basins (http://www.arb.ca.gov/desig/airbasins/airbasins.htm).

What does this measure tell us?   

    • This measure can give an idea of which air basin residents are at risk for long-term exposure to PM10

    • This measure can be used to inform the public and policy makers about the degree of potential exposure to particle pollution within a air basin during a year and over time (trends)

What can’t this measure tell us?

    • This measure does not provide information regarding the severity (or maximum concentrations) of potential exposures

See the latest results for this measure on our data query tool.


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