Mortality Displacement and Absence of Threshold: Issues Relating to the Proposed New Morro Bay Power Plant
Bonita Churney and Pamela Soderbeck – December 2001
The adverse health impacts resulting from even small increases in ambient concentrations of inhalable particulate matter (PM10) are quite significant and widely documented by public health professionals. These effects are particularly significant for the most susceptible populations, which include the elderly, those with pre-existing cardiovascular disease (CVD), those with pre-existing respiratory diseases, and those with other potentially fatal chronic illnesses such as diabetes, as well as children and infants. These effects on susceptible populations other than children are discussed in connection with the anticipated increases in PM10 concentrations that will result in Morro Bay, with the proposed new Morro Bay Power Plant (MBPP) compared to the existing plant. Morro Bay is a unique city in many ways, one of which is the relatively high number of elderly residents (24% of the total population).
All cause mortality resulting from increased PM10 concentrations is higher for this group and there are even greater increases in CVD mortality and respiratory disease mortality. This is found when examining the short term, e.g., daily mortality increases associated with daily increases in PM concentrations, as well as chronic mortality increases. These effects are supported by findings of increased risks of hospital admissions for these groups as well. These significant increases in daily mortality rates are not merely the result of mortality displacement (shortening one’s life by a day or two). These significant increases in mortality risks are also linear, meaning a reduction of 1 µg/m3 in PM10/PM2.5 has the same benefit whether the existing ambient concentration is at 15 or 90 µg/m3.
In addition to the mortality risks, there are additive increased health effects in the form of increased hospital admissions and other measures of morbidity from increases in PM10/2.5 of the magnitude expected with the new MBPP. These increased risks include increased hospital admissions for the elderly generally and for both CVD and various respiratory diseases, as well as for diabetes. Other documented significant adverse health effects associated with increases in PM2.5 and PM10 include increased heart rate, decreased heart rate variability, increased incidences of dysrhythmia, and increased defibrillator responses, all of which are recognized risks for CVD mortality.
These increased risks will occur at a significant level in Morro Bay as a result of the increased PM2.5 emissions and resulting concentrations from the new MBPP as compared to the existing plant. Moreover, these are all risks that can be avoided either with modifications to the MBPP as it is now proposed or with a “no project” alternative.
Click below to read the entire report (PDF):
Effects of Particulate Air Pollution on Susceptible Populations Other than Children