PubMed Health⌕ Search

Biomedical subjects

D W Dockery

Publications and source records attributed to D W Dockery.

At least 19 recordsLinked to original sources
PubMed1999

Oxygen saturation, pulse rate, and particulate air pollution: A daily time-series panel study.

Although epidemiological studies have linked particulate air pollution with cardiopulmonary mortality, underlying biological mechanisms remain largely unknown. Unexplored pathophysiological pathways include transient declines in blood oxygenation and/or changes in cardiac rhythm following particulate exposure. In this study, blood oxygen saturation using pulse oximetry (SpO2) and pulse rate were measured daily on a panel of 90 elderly subjects during the winter of 1995-1996 in Utah Valley. Associations of SpO2 and pulse rate with respirable particulate pollution (particles with an aerodynamic diameter </= a nominal 10 microm [PM10]) were evaluated. SpO2 was not consistently associated with PM10. Pulse rate and the odds of the pulse rate being elevated by 5 or 10 beats per minute (beats/min) were associated with PM10 on the previous 1 to 5 d. A 100 microg/m3 increase in previous-day PM10 was associated with an average increase of 0.8 beats/min and 29 and 95% increased odds of the pulse rate being elevated by 5 or 10 beats/min, respectively. Although there was little evidence of pollution-related hypoxia, alterations in pulse rate could reflect cardiac rhythm changes and may be part of the pathophysiology linking particles to cardiopulmonary mortality. The observed lag structure is consistent with particulate-induced pulmonary inflammation and cytokine release, but the biological relevance requires further study.

Aged↗
PubMed1999

Daily changes in oxygen saturation and pulse rate associated with particulate air pollution and barometric pressure.

Epidemiologic studies have linked fine particulate air pollution with increases in morbidity and mortality rates from cardiopulmonary complications. Although the underlying biologic mechanisms responsible for this increase remain largely unknown, potential pathways include transient declines in blood oxygenation and changes in pulse rate following exposures to particulate air pollution episodes. This study evaluated potential associations between daily measures of respirable particulate matter (PM) with pulse rate and oxygen saturation of the blood. Pulse rate and oxygen saturation (Spo2) using pulse oximetry were measured daily in 90 elderly subjects living near air pollution monitors during the winter of 1995-96 in Utah Valley. We also evaluated potential associations of oxygen saturation and pulse rate with barometric pressure. Small but statistically significant positive associations between day-to-day changes in Spo2 and barometric pressure were observed. Pulse rate was inversely associated with barometric pressure. Exposure to particulate pollution was not significantly associated with Spo2 except in male participants 80 years of age or older. Increased daily pulse rate, as well as the odds of having a pulse rate 5 or 10 beats per minute (bpm) above normal (normal is defined as the individual's mean pulse rate throughout the study period), were significantly associated with exposure to particulate pollution on the previous 1 to 5 days. The medical or biologic relevance of these increases in pulse rate following exposure to particulate air pollution requires further study.

Aged↗
PubMed1999

Particulate and ozone pollutant effects on the respiratory function of children in southwest Mexico City.

We assessed the contributions of particulate matter with aerodynamic diameters < or =10 and < or =2.5 microm (PM2.5 and PM10) and ozone (O3) to peak expiratory flow (PEF) and respiratory symptoms in 40 schoolchildren 8-11 years of age for 59 days during three periods in 1991 at a school in southwest Mexico City. We measured peak expiratory flow in the morning on the children's arrival at school and in the afternoon before their departure from school. Separately for morning and afternoon, we normalized each child's daily measurement of peak flow by subtracting his or her mean peak flow from the daily measurement. Child-specific deviations were averaged to obtain a morning and afternoon mean deviation (APEF) for each day. Mean 24-hour O3 level was 52 parts per billion (ppb; maximum 103 ppb); mean 24-hour PM2.5 and PM10 were 30 microg/m3 (maximum 69 microg/m3) and 49 microg/m3 (maximum 87 microg/m3), respectively. We adjusted moving average and polynomial distributed lag multiple regression analyses of APEF vs pollution for minimum daily temperature, trend, and season. We examined effects of PM2.5, PM10, and O3, on deltaPEF separately and in joint models. The models indicated a role for both particles and O3 in the reduction of peak expiratory flow, with shorter lags between exposure and reduction in peak expiratory flow for O3 than for particle exposure (0-4 vs 4-7 days). The joint effect of 7 days of exposure to the interquartile range of PM2.5 (17 microg/m3) and O3 (25 ppb) predicted a 7.1% (95% confidence interval = 11.0-3.9) reduction in morning peak expiratory flow. Pollutant exposure also predicted higher rates of phlegm; colinearity between pollutants limited the potential to distinguish the relative contribution of individual pollutants. In an area with chronically high ambient O3 levels, school children responded with reduced lung function to both O3 and particulate exposures within the previous 1 to 2 weeks.

Air Pollution↗
PubMed1998

Limitations of a home characteristics questionnaire as a predictor of indoor allergen levels.

We examined associations between reported home characteristics and levels of indoor allergens in 499 homes of a birth cohort of children of allergic/asthmatic families from the Boston area. The risk of having dust mite allergen (Der f 1 or Der p 1) > or = 2 microg/g on the bedroom floor was highest in houses, but 16% of apartments had levels this high. Compared with that from smooth floors, dust from carpeted bedroom floors had 2.1 times the risk of dust mite allergen > or = 10 microg/g, but levels exceeded 2 microg/g in 32% of uncarpeted floors. The risk of dust mite allergen > or = 10 microg/g of dust from plastic-encased mattresses was 0.5 times that for cloth mattresses, but levels in 21% of plastic-encased mattresses were > or = 2 microg/g. In 93% of homes with and 3% of homes without cats, Fel d 1 was > or = 8 microg/g, but 34% of homes without cats had Fed d 1 > or = 1 microg/g. Cockroach allergen (Bla g 1 or Bla g 2) was > or = 2 U/g of kitchen dust in 26% of apartments and only 6% of houses, and it was detected in 48% of homes with no reported signs of cockroaches in the previous 12 mo. Home characteristics reporting is a relatively weak predictor of the absence of allergen, and exposure can occur even when no cats are present, beds are encased in plastic, no carpets are present, and no signs of cockroaches have been reported.

Air Pollution, Indoor↗
PubMed1998

Association between PM10 and decrements in peak expiratory flow rates in children: reanalysis of data from five panel studies.

Panel studies have found 1-3% increases in reports of acute respiratory symptoms associated with each 10 microg x m(-3) increase in ambient concentrations of particles with a 50% cut-off aerodynamic diameter of 10 microm (PM10). Statistically significant decrements in population mean peak expiratory flow (PEF) have also been observed but their magnitude is only about 0.1% for the same exposure. This study evaluated whether this difference is due to the different measurement scales used for the expression of the effects of air pollution on PEF and respiratory symptoms. The association between the prevalence of large decrements in PEF (more than 10% or 20% below the median) and PM10 concentrations was analysed using data from five recent panel studies. The effect estimates were compared to the effect estimates from original studies based on the population mean PEF. The decrement in the population mean PEF for an increase of 10 microg x m(-3) of the same-day PM10 concentration was 0.07%, averaged over all panels. A significant relative increase of 2.7% (95% confidence interval 1.6-3.8) in the prevalence of PEF decrements greater than 10% was associated with the same exposure. In conclusion, defining the peak expiratory flow response by the prevalence of large decrements provides effect estimates of a comparable magnitude to effect estimates for the prevalence of reports of acute lower respiratory symptoms.

Air Pollutants↗
PubMed1998

Pulmonary toxicity in hamsters of smoke particles from Kuwaiti oil fires.

The Kuwaiti oil wells set on fire by retreating Iraqi troops at the end of the Persian Gulf War released complex particles, inorganic and organic gases, and hydrocarbons into the atmosphere, damaging the environment where many people live and work. In this study, we assessed the health effects of particles from the Kuwaiti oil fires by instilling hamsters intratracheally with particles (<3.5 microM in size) collected in Ahmadi, a residential area in Kuwait located downwind of hundreds of oil fires. Twenty-four hours after instillation, we performed bronchoalveolar lavage (BAL) to assess various indicators of pulmonary inflammation, including neutrophil and macrophage numbers; albumin, an index of air-blood barrier permeability; and activities of three enzymes: lactate dehydrogenase (LDH; an indicator of cell injury), myeloperoxidase (MPO; which indicates activation of neutrophils), and ss-N-acetylglucosaminidase (GLN; which is indicative of damage to macrophages or neutrophils). We compared the response of hamsters instilled with particles from Ahmadi to animals instilled with urban particles collected in St. Louis, Missouri. We also compared the Ahmadi particles against a highly fibrogenic positive control ([alpha]-quartz) and a relatively nontoxic negative control (iron oxide). When compared to hamsters instilled with particles from St. Louis, the animals treated with the Ahmadi particles had between 1.4- and 2.2-fold more neutrophils in their BAL fluids. The Ahmadi hamsters had more macrophages and lower MPO and LDH activities, but comparable albumin levels and GLN activities. Thus, the acute toxicity of the Ahmadi particles was roughly similar to that of urban particles collected in the United States, when identical masses were compared. However, the relatively higher concentrations of particles measured in Kuwait and Saudi Arabia during the oil fires (at times more than 16 times higher than the EPA standard) is of particular concern. In addition, since the long-term effects of exposure to these particles remains unknown, further studies are needed to fully assess the health effects of the Kuwaiti oil fires.

Animals↗
PubMed1998

Effects of ozone and other pollutants on the pulmonary function of adult hikers.

This study evaluated the acute effects of ambient ozone (O3), fine particulate matter (PM2.5), and strong aerosol acidity on the pulmonary function of exercising adults. During the summers of 1991 and 1992, volunteers (18-64 years of age) were solicited from hikers on Mt. Washington, New Hampshire. Volunteer nonsmokers with complete covariates (n = 530) had pulmonary function measured before and after their hikes. We calculated each hiker's posthike percentage change in forced expiratory volume in 1 sec (FEV1), forced vital capacity (FVC), the ratio of these two (FEV1/FVC), forced expiratory flow between 25 and 75% of FVC(FEF25-75%), and peak expiratory flow rate (PEFR). Average O3 exposures ranged from 21 to 74 ppb. After adjustment for age,sex, smoking status (former versus never), history of asthma or wheeze, hours hiked, ambient temperature, and other covariates, there was a 2.6% decline in FEV1 [95% confidence interval (CI), 0.4-4.7; p = 0.02] and a 2.2% decline in FVC (CI, 0.8-3.5; p =0.003) for each 50 ppb increment in mean O3. There were consistent associations of decrements in both FVC (0.4% decline; CI,0.2-0.6, p = 0.001) and PEFR (0.8% decline; CI, 0.01-1.6; p = 0.05) with PM2.5 and of decrements in PEFR (0.4% decline; CI, 0.1-0.7; p = 0.02) with strong aerosol acidity across the interquartile range of these exposures. Hikers with asthma or a history of wheeze (n = 40) had fourfold greater responsiveness to ozone than others. With prolonged outdoor exercise, low-level exposures to O3, PM2.5, and strong aerosol acidity were associated with significant effects on pulmonary function among adults. Hikers with a history of asthma or wheeze had significantly greater air pollution-related changes in pulmonary function.

Adolescent↗
PubMed1997

Risk of lung cancer from environmental exposures to tobacco smoke.

Epidemiologic evidence on the relation between environmental tobacco smoke and cancer is reviewed. The labeling of tobacco smoke as an environmental cause of lung cancer has been challenged based on allegations of bias in the epidemiologic data. However, tobacco smoke has been shown to increase the risk of lung cancer down to the lowest exposure levels. Environmental tobacco smoke contains the same carcinogenic compounds as those found in the tobacco smoke inhaled directly by the smoker. Nonsmokers environmentally exposed have elevated levels of tobacco smoke byproducts in biological samples. These observations alone are sufficient to identify tobacco smoke as an environmental carcinogen. The epidemiologic studies showing that environmental exposure to tobacco smoke is associated weakly but consistently with increased risk of lung cancer. While these epidemiologic studies have been challenged, it does not appear that the observed epidemiologic associations are due to misclassification or confounding. Indeed, the epidemiologic results, particularly among the studies with superior data collection methods and better control of bias and confounding, find consistent associations between environmental tobacco smoke and lung cancer. This paper summarizes the evidence that environmental exposure to tobacco smoke increases the risk of lung cancer, and considers the criticisms of the epidemiologic evidence which have been raised.

Bias↗
PubMed1997

Medication use modifies the health effects of particulate sulfate air pollution in children with asthma.

Previous controlled studies have indicated that asthma medication modifies the adverse effects of sulfur dioxide (SO2) on lung function and asthma symptoms. The present report analyzed the role of medication use in a panel study of children with mild asthma. Children from Sokolov (n = 82) recorded daily peak expiratory flow (PEF) measurements, symptoms, and medication use in a diary. Linear and logistic regression analyses estimated the impact of concentrations of sulfate particles with diameters less than 2.5 microns, adjusting for linear trend, mean temperature, weekend (versus weekday), and prevalence of fever in the sample. Fifty-one children took no asthma medication, and only 31 were current medication users. Most children were treated with theophylline; only nine used sprays containing beta-agonist. For the nonmedicated children, weak associations between a 5-day mean of sulfates and respiratory symptoms were observed. Medicated children, in contrast, increased their beta-agonist use in direct association with an increase in 5-day mean of sulfates, but medication use did not prevent decreases in PEF and increases in the prevalence of cough attributable to particulate air pollution. Medication use was not a confounder but attenuated the associations between particulate air pollution and health outcomes.

Adolescent↗
PubMed1997

Short-term effects of particulate air pollution on respiratory morbidity in asthmatic children.

Short-term effects of air pollution (consisting primarily of sulphur dioxide and particulate matter but with low acidity) on respiratory morbidity were studied in asthmatic children from Sokolov, Czech Republic. Eighty nine children with asthma, who recorded daily peak expiratory flow measurements, symptoms and medication use in a diary, were analysed for 7 months during the winter of 1991-1992. Air pollution measurements included: SO2, total suspended particulates (TSPs), inhalable particles, ie. particulate matter of aerodynamic diameter < or = 10 microm, particle strong acidity (PSA) and fine particle sulphate concentration (SO4). Linear and logistic regression analyses estimated the impact of air pollutants adjusted for trend, temperature and weekend and autocorrelated errors. Exposure to elevated levels of air pollution was associated with decreased peak expiratory flow rates, increased respiratory symptoms, increased prevalence of school absence and fever, and increased medication use. Prolonged exposure to particle SO4 showed the largest effect estimates. At the end of January, an air pollution episode occurred, during which respiratory symptoms, prevalence of fever, school absence and asthma medication increased. The association between respiratory symptoms and particulate SO4 was highly dependent on this episode, whilst the associations between lung function and SO4 as well as between fever and SO4 were still observed when this air pollution episode was excluded. Some evidence was found that exposure to air pollution might have enhanced the respiratory symptoms while children were experiencing respiratory infections. In this study, a panel of children with mild asthma experienced small decreases in peak expiratory flow and increased dyspnoea in association with fine particles formed during air pollution episodes.

Adolescent↗
PubMed1996

Effects of cigarette smoking on lung function in adolescent boys and girls.

BACKGROUND: Little is known about the sex-specific effects of cigarette smoking on the level and growth of lung function in adolescence, when 71 percent of people in the United States who smoke tried their first cigarette. METHODS: We studied the effects of cigarette smoking on the level and rate of growth of pulmonary function in a cohort of 5158 boys and 4902 girls 10 to 18 years of age, examined annually between 1974 and 1989 in six cities in the United States. RESULTS: We found a dose-response relation between smoking and lower levels of both the ratio of forced expiratory volume in one second to forced vital capacity (FEB1/FVC) and the forced expiratory flow between 25 and 75 percent of FVC (FEF25-75). Each pack per day of smoking was associated with a 3.2 percent reduction in FEF25-75 for girls (P=0.01) and a 3.5 percent reduction in FEF25-75 for boys (P=0.007). Whereas the FVC level was elevated in smokers, the rate of growth of FVC and FEV1 was reduced. Among adolescents of the same sex, smoking five or more cigarettes a day, as compared with never smoking, was associated with 1.09 percent slower growth of FEV1 per year in girls (95 percent confidence interval 0.70 to 1.47) and 0.20 percent slower growth in boys (95 percent confidence interval, -0.16 to 0.56), and with 1.25 percent slower growth of FEF25-75 per year in girls (95 percent confidence interval 0.38 to 2.13) and 0.93 percent slower growth in boys (95 percent confidence interval, 0.21 to 1.65). Whereas girls who did not smoke reached a plateau of lung function at 17 to 18 years of age, girls of the same age who smoked had a decline of FEV1 and FEF25-75. CONCLUSION: Cigarette smoking is associated with evidence of mild airway obstruction and slowed growth of lung function in adolescents. Adolescent girls may be more vulnerable than boys to the effects of smoking on the growth of lung function.

Adolescent↗
PubMed1996

Acute health effects of exposure to high levels of air pollution in eastern Europe.

Acute effects of winter-type air pollution characterized by high levels of SO2, moderate levels of particles, and low acidity were studied. A panel of 155 asthmatic children and 102 adults with a history of asthma from the former German Democratic Republic cities of Erfurt and Welmar and from the Czech Republic city of Sokolov participated from September 1990 through June 1992. The panelists recorded daily symptoms, medication intake, and peak expiratory flow (PEF). Statistical analysis was based on linear regression of population-averaged time series controlling for trend, meteorology, and autocorrelation. A temporospatial time series approach was also applied to the data to eliminate possible confounding by some known or unknown variables that occurred simultaneously in two of the study areas. Weak same-day effects and a stronger cumulative effect of air pollution on children was observed both for PEF and for symptoms. PEF decreased -0.90% (-1.35 to -0.46%), and a symptom score increased 14.7% (0.8-28.6%) in association with an average increase of 128 micrograms/m3 SO2 over the previous 5 days. Effects on adults were smaller and less consistent. Morbidity of children was best predicted by SO2 and sulfate concentrations. The authors conclude that prolonged, high exposure to winter-type pollution was associated with small adverse health effects in asthmatics.

Adolescent↗
PubMed1996

Fungus spores, air pollutants, and other determinants of peak expiratory flow rate in children.

The impact of summertime haze episodes on daily variations in symptoms and peak expiratory flow rates (PEFRs) was examined in a study of 108 children living in State College, Pennsylvania, during the summer of 1991. Twice daily, each child recorded symptoms, PEFRs and hours spent outdoors. Environmental measurements included daily 12- and 24-hour averages for meteorologic and air pollutant variables and 24-hour average fungus spore concentrations. A 10,000-spore/m3 increment in Cladosporium spore concentration was associated with a deficit in morning PEFR (-1.0 liters/minute, 95% confidence interval (CI) -1.9 to -0.2). A 60-spore/m3 increment in Epicoccum spore concentration was associated with increased incidence of morning cough (odds ratio (OR) = 1.8, 95% CI 1.0-3.2) and a deficit in morning PEFR (-1.5 liters/minute, 95% CI -2.8 to -0.2). Fungi spore counts were not associated with respirable particle mass. A 125-nmol/m3 increment in 12-hour daytime particle-strong acidity was associated with a deficit in evening PEFR (-0.5 liters/minute, 95% CI -1.2 to 0.2) and increased incidence of cold episodes that evening or the subsequent morning (OR = 1.35, 95% CI 1.14-1.61). A 20-microgram/m3 increment in 24-hour respirable particles lagged by 24 hours was associated with a deficit in evening PEFR (-0.5 liters/minute 95% CI -1.4 to 0.4) and increased incidence of cough episodes that evening or the subsequent morning (OR = 1.37, 95% CI 1.13-1.66). These results confirm the acute effects of summertime particulate air pollution and suggest that aeroallergens have independent effects on respiratory symptoms and PEFR in children.

Air Microbiology↗
PubMed1996

Environmental tobacco smoke, wheezing, and asthma in children in 24 communities.

The association of exposure to environmental tobacco smoke (ETS) at home with asthma and several measures of wheeze was examined among 11,534 children aged 8 to 11 yr in 24 communities in the United States and Canada in 1988 through 1990. Information on the child's respiratory symptoms in the past year and history of exposure to ETS was provided by the child's mother on a questionnaire. After adjusting for potential confounders, children currently exposed to ETS were at greater risk of wheezing with colds (odds ratio [OR] = 1.7; 95% confidence interval [95% CI], 1.4 to 1.9), going to a hospital emergency room for wheeze (OR = 1.6; 95% CI, 1.2 to 2.2), and having persistent wheeze (OR = 1.4; 95% CI, 1.1 to 1.8). The relative odds of these symptoms increased with exposure level, and there was no evidence of a difference in the association with smoking by mother, father, or other adults. In contrast to wheeze symptoms, active doctor-diagnosed asthma and asthma medication use were not significantly associated with ETS exposure at home, possibly reflecting underdiagnosis of asthma, reporting bias, or smoking cessation by parents whose child is labeled asthmatic. We conclude that exposure to ETS is associated with wheezing symptoms, medical therapy for wheezing, and wheezing-related emergency department visits in U.S. and Canadian children.

Adult↗
PubMed1996

Health effects of acid aerosols on North American children: air pollution exposures.

Air pollution measurements were conducted over a 1-year period in 24 North American communities participating in a respiratory health study. Ozone, particle strong acidity, sulfate, and mass (PM10 and PM2.1) were measured in all communities. In 20 of the communities, sulfur dioxide, ammonia, nitric acid, nitrous acid, and particulate nitrate were measured. The sampler was located centrally in the community whenever possible and samples were collected every other day. Concentrations of particle strong acidity, mass, sulfate, and ozone were highly correlated both in the region of the country defined as a high-sulfur source area and in the downwind transport regions. These regions of the eastern United States and southern Canada experienced the greatest particle strong acidity, sulfate, and particle mass concentrations during the spring and summer months (May-September). The particle strong acidity concentrations were highest in regions close to the high sulfur emission areas of the United States; that is, in the area immediately to the west of the Appalachian Plateau and west of the Allegheny Mountains (western Pennsylvania, eastern Ohio, and West Virginia) up through southern Ontario. The frequency of particle strong acidity events decreased with transport distance from the region of highest sulfur emissions. Low particle strong acidity and sulfates were found at the western and midwestern sites of both the United States and Canada. Substantial concentrations of nitric acid were found in two of the California sites as well as many sites in the northeastern portion of the United States. Sites selected for the epidemiologic study provide a range of annual mean particle strong acidity exposures from below the limit of detection to more than 50 nmol/m3.

Aerosols↗
PubMed1996

Health effects of acid aerosols on North American children: respiratory symptoms.

We examined the respiratory health effects of exposure to acidic air pollution among 13,369 white children 8 to 12 years old from 24 communities in the United States and Canada between 1988 and 1991. Each child's parent or guardian completed a questionnaire. Air quality and meteorology were measured in each community for a 1-year period. We used a two-stage logistic regression model to analyze the data, adjusting for the potential confounding effects of sex, history of allergies, parental asthma, parental education, and current smoking in the home. Children living in the community with the highest levels of particle strong acidity were significantly more likely [odds ratio (OR) = 1.66; 95% confidence interval (CI) 1.11-2.48] to report at least one episode of bronchitis in the past year compared to children living in the least-polluted community. Fine particulate sulfate was also associated with higher reporting of bronchitis (OR = 1.65; 95% CI 1.12-2.42). No other respiratory symptoms were significantly higher in association with any of the air pollutants of interest. No sensitive subgroups were identified. Reported bronchitis, but neither asthma, wheeze, cough, nor phlegm, were associated with levels of particle strong acidity for these children living in a nonurban environment.

Aerosols↗
PubMed1996

Health effects of acid aerosols on North American children: pulmonary function.

We examined the health effects of exposure to acidic air pollution among children living in 24 communities in the United States and Canada. Parents of children between the ages of 8 and 12 completed a self-administered questionnaire and provided consent for their child to perform a standardized forced expiratory maneuver at school in 22 of these communities. Air quality and meteorology were measured in each community for the year preceding the pulmonary function tests. Forced vital capacity (FVC) and forced expiratory volume in 1 sec (FEV1.0) measurements of 10,251 white children were examined in a two-stage regression analysis that adjusted for age, sex, height, weight, and sex-height interaction. In this study, a 52 nmol/m3 difference in annual mean particle strong acidity was associated with a 3.5% (95% CI, 2.0-4.9) decrement in adjusted FVC and a 3.1% (95% CI, 1.6-4.6) decrement in adjusted FEV1.0. The FVC decrement was larger, although not significantly different, for children who were lifelong residents of their communities (4.1%, 95% CI, 2.5-5.8). The relative odds for low lung function (that is, measured FVC less than or equal to 85% of predicted), was 2.5 (95% CI, 1.8-3.6) across the range of particle strong acidity exposures. These data suggest that long-term exposure to ambient particle strong acidity may have a deleterious effect on lung growth, development, and function.

Aerosols↗