nitrogen-dioxide and Virus-Diseases

Although the everyday experience of asthmatic patients provides ample anecdotal evidence that environmental exposures provoke bronchospasm, it has proved more difficult to assess the impact of air quality on the timing of asthma attacks and the prevalence of asthma in populations. Spectacular 'asthma epidemic days' are sometimes attributable to exceptional outdoor aero-allergen exposures. By comparison, effects of inorganic particles and gaseous pollutants in outdoor air on the incidence of asthma attacks are subtle and poorly quantified. Environmental tobacco smoke and mould growth are the indoor factors most consistently associated with respiratory morbidity, but their roles in initiating allergic asthma remain uncertain. Evidence relating asthma risk to fumes from gas cooking, and to allergens from dust mites and household pets remains confused and controversial. It is unlikely that trends in either outdoor or indoor air pollution have contributed substantially to the rise in prevalence of asthma and allergic disease in recent decades.

Topics: Adolescent; Adult; Air Pollutants; Allergens; Animals; Animals, Domestic; Asthma; Bedding and Linens; Child; Child, Preschool; Dust; Fossil Fuels; Humans; Lightning; Mites; Nitrogen Dioxide; Poaceae; Pollen; Prevalence; Seasons; Spores; Tobacco Smoke Pollution; Virus Diseases

The associations between viral etiology of acute respiratory infections (ARI) with meteorological factors and air pollutants among children is not fully understood. This study aimed to explore the viral etiology among children hospitalized for ARI and the association of meteorological factors and air pollutants with children hospitalization due to viral ARI.. Electronic health record data about children (aged between 1 month and 14 years) admitted for ARI at Kiang Wu Hospital in Macao between 2014 and 2017 was analyzed retrospectively. xMAP multiplex assays were used to detect viruses in the nasopharyngeal swab and distributed-lag nonlinear model (DLNM) was used to evaluate associations.. Among the 4880 cases of children hospitalization due to ARI, 3767 (77.2%) were tested positive for at least one virus and 676 (18%) exhibited multiple infections. Enterovirus (EV)/rhinovirus (HRV), adenovirus (ADV), respiratory syncytial virus (RSV) and influenza virus (IFV) were the most common viral pathogens associated with ARI and human bocavirus (hBOV) exhibited the highest multiple infection rates. Meteorological factors and air pollutants (PM. The effects of mean temperature, relative humidity and air pollutants should be taken into account when considering management of ARI among children.

Topics: Air Pollutants; Child; Hospitalization; Humans; Infant; Macau; Meteorological Concepts; Nitrogen Dioxide; Respiratory Syncytial Virus, Human; Respiratory Tract Infections; Retrospective Studies; Virus Diseases; Viruses

This study investigated whether outpatient visits of acute upper respiratory infections for children aged less than 15 years are associated with temperature, air pollutants and circulating respiratory viruses in Taipei, Taiwan, from 2003 to 2007.. Outpatient records for acute upper respiratory infections (ICD9 CM codes: 460, 462, 463,464, 465.9 and 487) in a randomly selected sample (n=39,766 children in 2005) was used to estimate the cumulative relative risks (RR) associated with average temperature lasting for 8 days (lag 0-7 days), air pollutants (NO2, O3 and PM(2.5)) lasting for 6 days (lag 0-5 days), and virus-specific positive isolation rate lasting for 11 days (lag 0-10 days) using distributed lag non-linear models after controlling for relative humidity, wind speed, day of week, holiday effects and long-term trend.. Average temperature of 33 °C was associated with the lowest risk for outpatient visits of acute upper respiratory infections. Relative to 33 °C, cumulative 8-day RR was highest at 15 °C of ambient average temperature [RR=1.94; 95% confidence interval (CI): 1.78, 2.11]. With the first quartile as reference, cumulative 6-day RRs were 1.25 (95% CI: 1.21, 1.29) for NO2, 1.04 (95% CI: 1.01, 1.06) for O3, and 1.00 (95% CI: 0.98, 1.03) for PM(2.5) at the 95th percentile. Per-standard deviation (SD) increase of virus-specific isolation rate for influenza type A (SD=13.2%), type B (SD=8.76%), and adenoviruses (SD=5.25%) revealed statistical significance for overall 11-day RRs of 1.02 (95% CI: 1.01, 1.03), 1.05 (95% CI: 1.03, 1.06) and 1.04 (95% CI: 1.03, 1.05), respectively.. Current study suggested a positive association between outpatient visits for acute upper respiratory infections and ambient environment factors, including average temperature, air pollutants, and circulating respiratory viruses.

Topics: Air Pollution; Child; Humans; Nitrogen Dioxide; Respiratory Tract Infections; Risk Factors; Taiwan; Temperature; Virus Diseases; Viruses

A review of the health effects of relative humidity in indoor environments suggests that relative humidity can affect the incidence of respiratory infections and allergies. Experimental studies on airborne-transmitted infectious bacteria and viruses have shown that the survival or infectivity of these organisms is minimized by exposure to relative humidities between 40 and 70%. Nine epidemiological studies examined the relationship between the number of respiratory infections or absenteeism and the relative humidity of the office, residence, or school. The incidence of absenteeism or respiratory infections was found to be lower among people working or living in environments with mid-range versus low or high relative humidities. The indoor size of allergenic mite and fungal populations is directly dependent upon the relative humidity. Mite populations are minimized when the relative humidity is below 50% and reach a maximum size at 80% relative humidity. Most species of fungi cannot grow unless the relative humidity exceeds 60%. Relative humidity also affects the rate of offgassing of formaldehyde from indoor building materials, the rate of formation of acids and salts from sulfur and nitrogen dioxide, and the rate of formation of ozone. The influence of relative humidity on the abundance of allergens, pathogens, and noxious chemicals suggests that indoor relative humidity levels should be considered as a factor of indoor air quality. The majority of adverse health effects caused by relative humidity would be minimized by maintaining indoor levels between 40 and 60%. This would require humidification during winter in areas with cold winter climates. Humidification should preferably use evaporative or steam humidifiers, as cool mist humidifiers can disseminate aerosols contaminated with allergens.

Topics: Aerosols; Allergens; Bacterial Infections; Communicable Diseases; Formaldehyde; Fungi; Humans; Humidity; Hypersensitivity; Mites; Nitrogen Dioxide; Occupational Diseases; Ozone; Respiratory Tract Infections; Skin Diseases; Sulfur Dioxide; Virus Diseases

The ultrastructural morphogenesis of pulmonary lesions was studied in cats exposed to either aerosols of feline calicivirus (FCV) or high concentrations of NO2. Both directly injured alveolar lining cells, particularly type I cells. Necrosis of pneumocytes attended by an acute exudative response in the air exchange tissues was evident from 0 through 24 hours after exposure of cats to NO2 and from 12 through 96 hours after infection with FCV. The reparative process following alveolar injury was characterized by regenerative hyperplasia of type II pneumocytes, proliferation of stromal cells, and infiltration of mononuclear cells. Differences in the lesions produced by NO2 and FCV also were encountered. Endothelial necrosis was detected only after NO2 injury, whereas a marked infiltration of neutrophils and immunocytes was observed only after FCV injury. The FCV/NO2 experimental system in cats is well suited for studies of diffuse alveolar damage of toxic and viral etiology.

Topics: Animals; Bronchi; Caliciviridae; Cats; Inflammation; Lung Diseases; Necrosis; Nitrogen Dioxide; Pulmonary Alveoli; Virus Diseases