New Standards for Fine Particles Set by EPA
In 1997, after years of intensive scientific review, EPA set a new health standard for very tiny “fine” particles known as PM2.5, while retaining the standards for larger particles known as PM10.
PM2.5 means particles that measure less than 2.5 microns in diameter, particles so small that they penetrate into the small airways of the lungs. The new standard will provide protection to nearly 70 million Americans and will prevent 15,000 premature deaths each year.
The new standards have not yet been implemented, and are awaiting the collection of three years of monitorng data, and the completion of EPA’s periodic five-year review of the particulate matter (PM) standards.
Fine particulate matter consists of solid particles such as diesel soot and tiny aerosol particles of sulfates, nitrates, and carbonaceous soot. Fossil fuel combustion is the major source of fine particle air pollution.
In 1997, EPA established health standards for fine particulate matter (PM2.5) for the first time. Earlier standards set in 1987 regulated larger, inhalable particles known as PM10.
Epidemiological studies from around the world have reported an association between particulate air pollution and reductions in lung function, respiratory symptoms, school absenteeism, increased use of asthma medications, doctor visits, emergency room visits, hospital admissions, and premature death at levels common in U.S. cities.
· Long-term epidemiological studies indicating that fine particles increase the risk of early death have recently been validated by an independent reanalysis. New studies show that chronic exposure to particulate pollutions shortens lives by one to three years.
· A study of the 90 largest U.S. cities found strong evidence linking daily increases in particle pollutions at contemporary levels to increases in daily death rates, and in hospital admissions of the elderly. These results are consistent with a study of 12 European cities.
· Particulate pollution has been tied to low heart rate variability, a risk factor for heart attacks. A chamber study with human subjects found that concentrated air particles can induce pulmonary inflammation and increase concentrations of fibrinogin in the blood, a risk factor for clotting and heart attacks.
· Particulate pollution worsens bronchitis in asthmatic children. Children can experience declines in breathing ability and increased respiratory symptoms such as cough, phlegm production, and sore throat after particle exposure. Children with asthma are more susceptible to these effects than otherwise healthy children.
· Emergency room visits for children with asthma increase on high particle pollution days.
· EPA estimates that implementing the 1997 National Ambient Air Quality Standard for fine particles could prevent 15,000 premature deaths each year.
People most sensitive to fine particle pollution are infants and children, especially those with asthma, the elderly, and people with pre-existing heart disease, lung disease, and diabetes.
