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Extremely High Levels of PM2.5: Steps to Reduce Your Exposure


The U.S. AQI does not include recommendations for PM2.5 levels above 500, but levels are sometimes worse (“beyond index”).  What should I do?  

  • Pollution is hazardous at these levels.  Everyone should take steps to reduce their exposure when particle pollution levels are in this range.
  • Staying indoors – in a room or building with filtered air – and reducing your activity levels are the best ways to reduce the amount of particle pollution you breathe into your lungs.  Read on for more information on steps to help reduce your exposure to short episodes of high levels of PM2.5.
  • Links to recommendations for reducing exposure to smoke from fires are available below.  These recommendations may help reduce exposure during short-term pollution episodes in which PM2.5 levels are above 500, since fine particles (PM2.5) are the primary pollutant in wildfire smoke.

Who needs to take steps to reduce exposure when PM2.5 levels are “hazardous” or above on the AQI?

  • Everyone needs to take steps to protect themselves when pollution levels are “hazardous” and above.  Some people are at higher risk from PM2.5 exposure.  People most at risk from particle pollution exposure include those with heart or lung disease (including asthma and chronic obstructive pulmonary disease-COPD), older adults, and children.  Research indicates that pregnant women, newborns, and people with certain health conditions, such as obesity or diabetes, also may be more susceptible to PM-related effects.
    • Not sure if the heart disease category applies to you?  People with heart disease includes all people with known coronary artery disease, ischemic heart disease, history of angina and/or heart attack, stent placement, by-pass operation, heart failure, ventricular arrhythmia, peripheral vascular disease, history of stroke, transient ischemic attack (TIA), or cerebrovascular disease.  This group also includes older adults, because they are more likely to have undiagnosed cardiovascular disease, along with people with multiple risk factors for cardiovascular disease, such as high blood pressure, elevated cholesterol, smoking, and diabetes.
    • Why are children more at risk?  Children are more likely to be exposed to air pollution, because they often spend more time outdoors engaged in activity and play, and they breathe more air per pound of body weight than adults.  They are more susceptible to the effects of air pollution, because their airways are still developing.  In addition, children are more likely than adults to have asthma, which increases their risk.
  • If you are in an at-risk group, if you have heart or lung disease, if you are an older adult, or if you have children, talk with your doctor in advance about when and whether you should leave the area or move to a location with better indoor air quality.  When PM2.5 concentrations are high for a prolonged period of time, fine particles can build up indoors even though you may not be able to see them. 
  • If you are in an at-risk group, don’t wait until pollution reaches the “hazardous” category to take action to reduce your exposure.  Air quality is unhealthy for you when particle pollution levels reach the “unhealthy for sensitive groups” range, so you will need to take steps to reduce your exposure earlier and more often.  If you are healthy, begin taking steps when air pollution reaches the “unhealthy” category. 

How can I tell if particle pollution is affecting me?

  • Even if you are healthy, you may experience temporary symptoms such as irritation of the eyes, nose, and throat; coughing; phlegm; chest tightness; and shortness of breath. These symptoms should go away when air quality improves. 
  • If you have lung disease – including asthma and COPD – you may not be able to breathe as deeply or as vigorously as normal, and you may experience coughing, chest discomfort, wheezing, shortness of breath, and unusual fatigue.  Make sure you follow your doctor's directions about taking your medicines and following your asthma management plan.  If you have any of these symptoms, reduce your exposure to particles and follow your doctor's advice. Contact your doctor if symptoms persist or worsen. In the event of an emergency, anywhere in China, you can dial 120.  
  • If you have heart or vascular disease, particle exposure can cause serious problems – including worsening of your disease – in a short period of time.  Do not assume that you are safe just because you do not have symptoms.
    • Symptoms that may indicate a serious heart problem include: Chest discomfort (uncomfortable pressure, fullness, squeezing, or pain in the center of the chest that lasts more than a few minutes or goes away and comes back), discomfort in other areas of the upper body (pain or discomfort in one or both arms, the back, neck, jaw or stomach), shortness of breath, or other signs may include breaking out in a cold sweat, nausea or light-headedness.  Seek emergency medical treatment if you experience these symptoms.  In the event of an emergency anywhere in China, you can dial 120.  
    • Symptoms of a stroke include: Sudden numbness or weakness (in the face, arm or legs especially on one side of the body), confusion, trouble speaking or understanding, problems seeing in one or both eyes, dizziness, loss of balance or coordination or trouble walking, or severe headache with no known cause may indicate symptoms of a stroke.  Seek emergency medical treatment if you experience these symptoms.   In the event of an emergency anywhere in China, you can dial 120.     

What can I do to reduce my exposure to fine particle pollution when levels are extremely high?

  • Stay indoors in an area with filtered air.  Particle pollution can get indoors, so consider purchasing an air cleaner if you live in an area with high levels of particle pollution.  (See information on selecting an air cleaner below.)
    • Air cleaners that remove particles include high-efficiency mechanical filters and electronic air cleaners, such as electrostatic precipitators.  Avoid using an air cleaner that works by generating ozone, which will increase the pollution in your home.
    • If you do not have air cleaners in your home, try to go somewhere that does have air filtration.  This could, for example, be a friend’s home, if it has air filtration.   
  • Keep your activity levels low.
    • Avoid activities that make you breathe faster or more deeply.  This is a good day for indoor activities, such as reading or watching TV.  
  • If you cannot buy filters for your entire home, create a clean room for sleeping.
    • A good choice is a room with as few windows and doors as possible, such as a bedroom.
    • If the room has windows, keep them closed.
      • Run an air conditioner or central air conditioning system if you are certain your air conditioner does not draw air from outdoors and has a filter.  If the air conditioner provides a fresh air option, keep the fresh-air intake closed.  Make sure that the filter is clean enough to allow good air flow indoors.
    • Use an air filter in that room.  Avoid using an air cleaner that works by generating ozone. Those types of cleaners will increase the pollution in your home.
    • Follow steps for keeping pollution in your home low (see next section).
  • Take additional steps to keep pollution in your home low.  Air cleaners alone may not be enough.  Because particle pollution from the outdoor air can easily get inside, take steps to avoid adding even more pollution indoors when outdoor PM2.5 levels are high:
    • Avoid using anything that burns, such as wood fireplaces, gas logs and even candles or incense.
    • Keep the room clean – but don’t vacuum unless your vacuum has a HEPA filter.  That stirs up particles already inside your home. Wet mopping can help reduce dust.
    • Don’t smoke.
    • Be cautious when the weather is hot. If it is too hot to stay inside with the windows closed, or if you are in an at-risk group, go somewhere else with filtered air.
    • When air quality improves, open the windows and air out your home or office.


  • Selecting an air cleaner:
    • Air cleaners that remove particles include high-efficiency mechanical filters and electronic air cleaners, such as electrostatic precipitators.  Avoid using an air cleaner that works by generating ozone, which will increase the pollution in your home.
  • Should I wear a dust mask if I have to go outside?
    • Do not rely on dust masks for protection. Paper "comfort" or "dust" masks are designed to trap large particles, such as sawdust.  These masks will not protect your lungs from small particles such as PM2.5.  Scarves or bandanas won’t help either.
    • Disposable respirators known as N-95 or P-100 respirators will help if you have to be outdoors for a period of time.  It’s important that you wear the respirator correctly, however.  For information on how to use one, see:



How will I know when conditions are better?

  • Air quality conditions in Beijing can change rapidly.  Check the U.S. Embassy or Chinese government air quality monitoring web pages for the most recent hourly PM2.5 readings.  These readings can help you determine when to take steps to reduce your exposure.
  • Also pay attention to weather forecasts; these can help you plan your activities for times when air quality improves, such as when winds are forecast that clear the air.  When the air clears, and AQI readings are low, take advantage of these times to get outdoors.

Information sources:

Wildfire Smoke - A Guide for Public Health Officials. California Department of Public Health, U.S. Environmental Protection Agency, California Office of Environmental Health Hazard Assessment, Missoula County Health Department, California Air Resources Board. July 2008.

AirNow website information on wildfire smoke: ;

CDC information: Protect yourself from wildfire smoke:

California Air Resources Board: