John D. Spengler

An association between air pollution and mortality in six U.S. cities

BACKGROUND Recent studies have reported associations between particulate air pollution and daily mortality rates. Population-based, cross-sectional studies of metropolitan areas in the United States have also found associations between particulate air pollution and annual mortality rates, but these studies have been criticized, in part because they did not directly control for cigarette smoking and other health risks. METHODS In this prospective cohort study, we estimated the effects of air pollution on mortality, while controlling for individual risk factors. Survival analysis, including Cox proportional-hazards regression modeling, was conducted with data from a 14-to-16-year mortality follow-up of 8111 adults in six U.S. cities. RESULTS Mortality rates were most strongly associated with cigarette smoking. After adjusting for smoking and other risk factors, we observed statistically significant and robust associations between air pollution and mortality. The adjusted mortality-rate ratio for the most polluted of the cities as compared with the least polluted was 1.26 (95 percent confidence interval, 1.08 to 1.47). Air pollution was positively associated with death from lung cancer and cardiopulmonary disease but not with death from other causes considered together. Mortality was most strongly associated with air pollution with fine particulates, including sulfates. CONCLUSIONS Although the effects of other, unmeasured risk factors cannot be excluded with certainty, these results suggest that fine-particulate air pollution, or a more complex pollution mixture associated with fine particulate matter, contributes to excess mortality in certain U.S. cities.

A QUANTITATIVE ASSESSMENT OF SOURCE CONTRIBUTIONS TO INHALABLE PARTICULATE MATTER POLLUTION IN METROPOLITAN BOSTON

In this paper, source apportionment techniques are employed to identify and quantify the major particle pollution source classes affecting a monitoring site in metropolitan Boston, MA. A Principal Component Analysis (PCA) of paniculate elemental data allows the estimation of mass contributions for five fine mass panicle source classes (soil, motor vehicle, coal related, oil and salt aerosols), and six coarse panicle source classes (soil, motor vehicle, refuse incineration, residual oil, salt and sulfate aerosols). Also derived are the elemental characteristics of those source aerosols and their contributions to the total recorded elemental concentrations (i.e. an elemental mass balance). These are estimated by applying a new approach to apportioning mass among various PCA source components: the calculation of Absolute Principal Component Scores, and the subsequent regression of daily mass and elemental concentrations on these scores.

Air pollution and daily mortality: Associations with particulates and acid aerosols

The association between total daily mortality and air pollution was investigated for a 1-year period (September 1985 through August 1986) in St. Louis and in the counties in eastern Tennessee surrounding Kingston/Harriman. The purpose of this study was to evaluate the relative importance of various measures of particulate and gaseous air pollution as predictors of daily mortality. Concentrations of inhalable particles (PM10), fine particles (PM2.5), the elemental composition of these particles, and aerosols acidity were measured daily during the period of study. The effect of each air pollutant on daily mortality was estimated after controlling for meteorologic and seasonal influences. Total mortality in St. Louis was found to increase 16% (95% CI-1 to 33%) for each 100 micrograms/m3 increase in PM10, and by 17% (95% CI-12 to 57%) in eastern Tennessee. Positive but progressively weaker associations were found with PM2.5, sulfate, and aerosol acidity concentrations in both communities. Associations with gaseous pollutants--sulfur dioxide, nitrogen dioxide, and ozone--were all far from statistical significance. Because of the short monitoring period for daily particulate air pollution, the power of this study to detect associations was limited. Nevertheless, statistically significant associations with PM10 were found in St. Louis, and, more importantly, the estimated effects were consistent between the two communities studied and with other reported analyses of the effects of particles on daily mortality. These data suggest that the acidity of particles is not as important in associations with daily mortality as the mass concentrations of particles.

Ventilation rates and health: multidisciplinary review of the scientific literature

UNLABELLED The scientific literature through 2005 on the effects of ventilation rates on health in indoor environments has been reviewed by a multidisciplinary group. The group judged 27 papers published in peer-reviewed scientific journals as providing sufficient information on both ventilation rates and health effects to inform the relationship. Consistency was found across multiple investigations and different epidemiologic designs for different populations. Multiple health endpoints show similar relationships with ventilation rate. There is biological plausibility for an association of health outcomes with ventilation rates, although the literature does not provide clear evidence on particular agent(s) for the effects. Higher ventilation rates in offices, up to about 25 l/s per person, are associated with reduced prevalence of sick building syndrome (SBS) symptoms. The limited available data suggest that inflammation, respiratory infections, asthma symptoms and short-term sick leave increase with lower ventilation rates. Home ventilation rates above 0.5 air changes per hour (h(-1)) have been associated with a reduced risk of allergic manifestations among children in a Nordic climate. The need remains for more studies of the relationship between ventilation rates and health, especially in diverse climates, in locations with polluted outdoor air and in buildings other than offices. PRACTICAL IMPLICATIONS Ventilation with outdoor air plays an important role influencing human exposures to indoor pollutants. This review and assessment indicates that increasing ventilation rates above currently adopted standards and guidelines should result in reduced prevalence of negative health outcomes. Building operators and designers should avoid low ventilation rates unless alternative effective measures, such as source control or air cleaning, are employed to limit indoor pollutant levels.

Indoor-outdoor relationships of respirable sulfates and particles

Abstract Indoor and outdoor concentrations of respirable particulates and sulfates have been measured in 68 homes in six cities for at least 1 yr. A conservation of mass model was derived describing indoor concentrations in terms of outdoor concentrations, infiltration and indoor sources. The measured data were analysed to identify important building characteristics and to quantify their effect. The mean infiltration rate of outdoor fine particulates was found to be approximately 70%. Cigarette smoking was found to be the dominant indoor source of respirable particulates. Increased indoor concentrations of sulfates were found to be associated with smoking and also with gas stoves. The effect of full air conditioning of the building was to reduce infiltration of outdoor fine particulates by about one half, while preventing dilution and purging of internally generated pollutants. The model for indoor respirable particulate and sulfate levels was found to compare well with measurements.

Low Flow Rate Sharp Cut Impactors for Indoor Air Sampling: Design and Calibration

Two single round nozzle impactors have been developed for use in Harvard’s indoor air pollution health study. Both impactors operate at flow rates of 4 L/m and are nearly identical, differing only in their cut sizes of 2.5 μm and 10 μm aerodynamic diameters. Two identical cascaded stages of the same cut size are used to obtain sharp cut-off characteristics. The particles are deposited on impaction plates made of oil impregnated, porous material to reduce particle bounce and are discarded. Only the particles collected on the afterfilter are analyzed. Special care has been taken to collect the particles uniformly on the afterfilter to aid in particle analysis. The jmpactors were calibrated with a vibrating orifice monodisperse aerosol generator. However, due to the sharp cut of the impactors, doublets and triplets in the calibration aerosols, even in small quantities, gave erroneous calibration curves. Therefore, the number of doublets and triplets in the challenging aerosols were measured and appropriate c...

Long-term measurements of respirable sulfates and particles inside and outside homes

The results of extensive indoor and outdoor monitoring for respirable size particles and the sulfate fraction of these particles are reported. These air pollution measurements were obtained in conjunction with an epidemiologic study in six U.S. cities: Portage, Wisconsin; Topeka, Kansas; Kingston/Harriman, Tennessee; Watertown, Massachusetts; St. Louis, Missouri: and Steubenville, Ohio. The major source of indoor particulate matter is cigarette smoke, which contributes approximately 20 μm−3 to the indoor concentrations for each smoker. Even in homes without smokers, indoor particle concentrations equal or exceed outdoor levels. The indoor respirable sulfate concentrations are consistently lower than outdoor concentrations.

Evaluation of an annular denuder/filter pack system to collect acidic aerosols and gases

A glass impactor was designed and evaluated along with an annular denude/filter pack system. The glass impactor has a 50% aerodynamic cutoff of 2.1 ..mu..m at a flow of 10 L min/sup /minus/1/ and allows a quantitative transfer of gases and fine particles to the annular denuder and filter pack components. Fine particle and gas concentrations, determined by using the glass impactor along with the annular denuder/filter pack, were in good agreement with those obtained with colocated reference samplers. Measurements of SO/sub 2/, HNO/sub 3/, and HNO/sub 2/ gases showed mean collection efficiencies of 0.993, 0.984, and 0.952, respectively, which compare well with predicted values. Additionally, it was found that artifact formation of nitrate and nitrite ions, representing about 5-10% of the concentrations of HNO/sub 3/ and HNO/sub 2/, occurs in the Na/sub 2/CO/sub 3/-coated annular denuder. Corrections for these artifacts were made with a second Na/sub 2/CO/sub 3/-coated annular denuder. The results of this pilot study suggest that the glass impactor/annular denuder/filter pack sampling system is suitable for measuring acidic aerosols and gases.

Asthma, Wheezing, and Allergies in Russian Schoolchildren in Relation to New Surface Materials in the Home

In a cross-sectional study of 5951 Russian 8-12-year-old schoolchildren, risks of current asthma, wheezing, and allergy were related to recent renovation and the installation of materials with potential chemical emissions. New linoleum flooring, synthetic carpeting, particleboard, wall coverings, and furniture and recent painting were determinants of 1 or several of these 3 health outcomes. These findings warrant further attention to the type of materials used in interior design.

Particulate matter and lung function growth in children: a 3-yr follow-up study in Austrian schoolchildren

The effects of particulate matter <10 µm in diameter (PM10) and other air pollutants on lung function were assessed in 975 schoolchildren, from eight communities in Lower Austria between 1994–1997. In each community, air pollution data were collected. Spirometry was performed twice a year. PM10 concentration (mean concentration between two subsequent lung-function measures in spring and autumn (summer interval) or between autumn and spring (winter interval)) showed a mean value of 17.36 µg·m−3 in the summer interval and 21.03 µg·m−3 in the winter interval. A slower increase in the forced expiratory volume in one second (FEV1) and midexpiratory flow between 25 and 75% of the forced vital capacity (MEF25–75) with age in children exposed to higher summer PM10 was observed in the 3-yr study period. After adjusting for potential confounders (sex, atopy, passive smoking, initial height, height difference, site, initial lung function) an increase of summer PM10 by 10 µg·m−3 was associated with a decrease in FEV1 growth of 84 mL·yr−1 and 329 mL·s−1·yr−1 for MEF25–75. Nitrogen dioxide and ozone also showed a negative effect on lung-function growth, confirming previous work. The authors concluded that long-term exposure to particulate matter <10 µm in diameter had a significant negative effect on lung-function proxy for the development of large (forced expiratory volume in one second) and small (midexpiratory flow between 25 and 75% of the forced vital capacity) airways, respectively, with strong evidence for a further effect of ozone and nitrogen dioxide on the development of forced vital capacity and forced expiratory volume in one second.