Exposure to complex mixtures of air pollutants produces in ammation in the upper and lower respiratory tract. Because the nasal cavity is a common portal of entry, respiratory and olfactory epithelia are vulnerable targets for toxicological damage. This study has evaluated, by light and electron microscopy and immunohistochemica l expression of nuclear factor-kappa beta (NF-j B) and inducible nitric oxide synthase (iNOS), the olfactory and respiratory nasal mucosae, olfactory bulb, and cortical and subcortical structures from 32 healthy mongrel canine residents in Southwest Metropolitan Mexico City (SWMMC), a highly polluted urban region. Findings were compared to those in 8 dogs from Tlaxcala, a less polluted, control city. In SWMMC dogs, expression of nuclear neuronal NF-j B and iNOS in cortical endothelial cells occurred at ages 2 and 4 weeks; subsequen t damage included alterations of the blood-brain barrier (BBB), degenerating cortical neurons, apoptotic glial white matter cells, deposition of apolipoprotein E (apoE)-positive lipid droplets in smooth muscle cells and pericytes, nonneuritic plaques, and neuro brillary tangles. Persistent pulmonary in ammation and deteriorating olfactory and respiratory barriers may play a role in the neuropatholog y observed in the brains of these highly exposed canines. Neurodegenerativ e disorders such as Alzheimer's may begin early in life with air pollutants playing a crucial role.

The principal objective of this study is to evaluate by light and electron microscopy (LM, EM) the heart tissues in stray southwest and northeast metropolitan Mexico City (SWMMC, NEMMC) dogs and compare their findings to those from 3 less polluted cities (Cuernavaca, Tlaxcala, and Tuxpam). Clinically healthy mongrel dogs, including 109 from highly polluted SWMMC and NEMMC, and 43 dogs from less polluted cities were studied. Dogs residing in cities with lower levels of pollutants showed little or no cardiac abnormalities. Mexico City and Cuernavaca dogs exhibited LM myocardial alterations including apoptotic myocytes, endothelial and immune effector cells, degranulated mast cells associated with scattered foci of mononuclear cells in left and right ventricles and interventricular septum, and clusters of adipocytes interspersed with mononuclear cells. Vascular changes included scattered polymorphonuclear leukocytes (PMN) margination and microthrombi in capillaries, and small venous and arteriolar blood vessels. Small veins exhibited smooth muscle cell hyperplasia, and arteriolar blood vessels showed deposition of particulate matter (PM) in the media and adventitia. Unmyelinated nerve fibers showed endoneural and epineural degranulated mast cells. EM examination of myocardial mast cells showed distended and abundant rough endoplasmic reticulum with few secretory granules. Myocardial capillaries exhibited fibrin deposition and their endothelial cells displayed increased luminal and abluminal pinocytic activity and the formation of anemone-like protrusions of the endothelium into the lumen. A close association between myocardial findings, lung epithelial and endothelial pathology, and chronic inflammatory lung changes was noted. The myocardial changes described in dogs exposed to ambient air pollutants may form the basis for developing hypothesis-driven mechanistic studies that might explain the epidemiological data of increased cardiovascular morbidity and mortality in people exposed to air pollutants.

Strategies to promote lifelong physical activity among children are needed to stem the adverse health consequences of inactivity. However, the health effects in growing children of long-term exposure to a polluted atmosphere are of deep concern. The atmosphere of south Mexico City (SMC) is characterized by a complex mixture of air pollutants, including ozone, particulate matter, and aldehydes. Radiological evidence suggests that small-airway disease could be present in clinically healthy, tobacco unexposed SMC children. The aim of this study was to assess, by means of a self-reported questionnaire, the physical education class times, daily outdoor after-school exposure time, and tobacco exposure in students attending public elementary and middle schools in SMC. Additionally, the time each student spent viewing television was assessed, and the authors measured each student's weight and height to determine body mass index (BMI, weight in kg divided by height in m2). The survey included 1,159 students in grades 7-9. The authors identified 2 critical periods of outdoor exposure in SMC children that coincided with significant concentrations of both ozone and particulate matter with diameters less than 10 micrometers (PM10): during school time after 11:00 A.M. and in the after-school outdoor activity period, usually extending from 1:00 P.M. to 6:00 P.M. Thirty-two percent of elementary and 61% of middle school students have physical education classes after 11:00 A.M. Students in SMC spend an average of 19.6 hr/wk outdoors in the after-school period, during which time they are engaged in light to moderate physical activities. Half of the students are exposed to tobacco smoke at home, and 7% of middle school students smoke. On the basis of BMI, 60% of students were classified as undernourished, overweight, or obese. No correlations were found between BMI and time spent viewing TV, time outdoors (on weekdays and weekends), or exposure to environmental tobacco smoke. Children and adolescents in SMC are participating in physical activities that enhance multiple components of health-related fitness. However, their activities occur outdoors, where they are exposed to high concentrations of air pollutants throughout the year. The authors believe that SMC children and adolescents must be educated, through both the school and health systems, regarding ways to obtain the necessary exercise while protecting themselves from the high concentrations of pollutants. Individuals should instruct and encourage young people to be involved in lifetime fitness activities and to eat balanced diets, if the goal is to control health-care costs, reduce disease incidence, and improve the overall quality of life of the Mexico City population.

Air pollution is a serious health problem in major cities in Mexico. The concentrations of monitored criteria pollutants have been above the US National Ambient Air Quality Standards for the last decade. To determine whether the number of primary malignant nasal and paranasal neoplasms has increased, we surveyed 256 such cases admitted to a major adult oncology hospital located in metropolitan Mexico City (MMC) for the period from 1976-1997 and to a tertiary hospital in Monterrey, an industrial city, for the period from 1993-1998. The clinical histories and histopathologic material were reviewed, and a brief clinical summary was written for each case. In the MMC hospital the number of newly diagnosed nasal and paranasal neoplasms per year for the period from 1976-1986 averaged 5.1, whereas for the next 11 years it increased to 12.5. The maximal increase was observed in 1995-1997, with an average of 20.3 new cases per year (P = 0.0006). The predominant neoplasms in these series were non-Hodgkin's lymphoma, squamous cell carcinoma, melanoma, adenocarcinoma, Schneiderian carcinoma, and nasopharyngeal carcinoma. In the Monterrey hospital a 2-fold increase in the numbers of newly diagnosed nasal and paranasal neoplasms was recorded between 1993 and 1998. The predominant MMC neoplasm in this series, namely nasal T-cell/natural killer cell non-Hodgkin's lymphoma, is potentially Epstein-Barr virus related. Nasal and paranasal malignant neoplasms are generally rare. Environmental causative factors include exposure in industries such as nickel refining, leather, and wood furniture manufacturing. Although epidemiologic studies have not addressed the relationship between outdoor air pollution and sinonasal malignant neoplasms, there is strong evidence for the nasal and paranasal carcinogenic effect of occupational aerosol complex chemical mixtures. General practitioners and ear, nose, and throat physicians working in highly polluted cities should be aware of the clinical presentations of these patients. Identification of this apparent increase in sinonasal malignant neoplasms in two urban Mexican polluted cities warrants further mechanistic and epidemiologic studies.

Air pollution is a serious health problem in major cities in Mexico. The concentrations of monitored criteria pollutants have been above the US National Ambient Air Quality Standards for the last decade. To determine whether the number of primary malignant nasal and paranasal neoplasms has increased, we surveyed 256 such cases admitted to a major adult oncology hospital located in metropolitan Mexico City (MMC) for the period from 1976-1997 and to a tertiary hospital in Monterrey, an industrial city, for the period from 1993-1998. The clinical histories and histopathologic material were reviewed, and a brief clinical summary was written for each case. In the MMC hospital the number of newly diagnosed nasal and paranasal neoplasms per year for the period from 1976-1986 averaged 5.1, whereas for the next 11 years it increased to 12.5. The maximal increase was observed in 1995-1997, with an average of 20.3 new cases per year (P = 0.0006). The predominant neoplasms in these series were non-Hodgkin's lymphoma, squamous cell carcinoma, melanoma, adenocarcinoma, Schneiderian carcinoma, and nasopharyngeal carcinoma. In the Monterrey hospital a 2-fold increase in the numbers of newly diagnosed nasal and paranasal neoplasms was recorded between 1993 and 1998. The predominant MMC neoplasm in this series, namely nasal T-cell/natural killer cell non-Hodgkin's lymphoma, is potentially Epstein-Barr virus related. Nasal and paranasal malignant neoplasms are generally rare. Environmental causative factors include exposure in industries such as nickel refining, leather, and wood furniture manufacturing. Although epidemiologic studies have not addressed the relationship between outdoor air pollution and sinonasal malignant neoplasms, there is strong evidence for the nasal and paranasal carcinogenic effect of occupational aerosol complex chemical mixtures. General practitioners and ear, nose, and throat physicians working in highly polluted cities should be aware of the clinical presentations of these patients. Identification of this apparent increase in sinonasal malignant neoplasms in two urban Mexican polluted cities warrants further mechanistic and epidemiologic studies.

Air pollution produces adverse health effects. The consequences of lifelong daily exposures to atmospheric pollutants upon the respiratory apparatus of healthy children are of considerable clinical importance. We investigated the association between exposure to a highly polluted urban environment with a complex mixture of air pollutants-ozone and particulate matter the predominant ones-and chest x-ray abnormalities in 59 healthy Mexican children who are lifelong residents of Southwest Metropolitan Mexico City (SWMMC), with a negative history of tobacco exposure and respiratory illnesses. Their clinical results and x-ray findings were compared to those of 19 Mexican control children, residents of a low-pollution area, with a similar negative history of tobacco exposure and respiratory illnesses. Ozone concentrations in SWMMC exceeded the U.S. Environmental Protection Agency (U.S. EPA) National Ambient Air Quality Standard (NAAQS) for O(3): 0.08 ppm as 1-h maximal concentration, not to be exceeded more than 4 times a year, on 71% of days in 1986 and 95% in 1997, with values as high as 0.48 ppm. Ozone maximal peaks are usually recorded between 2 and 5 pm coinciding with children's outdoor physical activities. Children in the control group reported no upper or lower respiratory symptomatology. Every SWMMC child complained of upper and/or lower respiratory symptoms, including epistaxis, nasal dryness and crusting, cough, shortness of breath, and chest discomfort. Children aged 7-13 yr had the most symptomatology, while 5- to 6-year olds and adolescents with the lowest number of statistically significant outdoor exposure hours had less respiratory symptoms. Bilateral symmetric mild lung hyperinflation was significantly associated with exposure to the SWMMC atmosphere (p = .0004). Chronic and sustained inhalation of a complex mixture of air pollutants, including ozone and particulate matter (PM), is associated with lung hyperinflation, suggestive of small airway disease, in a population of clinically healthy children and adolescents. Small airways are a target of air pollutants in SWMMC children, with ozone and PM being most likely responsible, based on experimental animal, controlled-chamber, and epidemiological data available. Our main concern is the potential likelihood for the development of chronic lung disease in this highly exposed population.

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