Diesel exhaust and asthma: hypotheses and molecular mechanisms of action.

Abstract

Several components of air pollution have been linked to asthma. In addition to the well-studied critera air pollutants, such as nitrogen dioxide, sulfur dioxide, and ozone, diesel exhaust and diesel exhaust particles (DEPs) also appear to play a role in respiratory and allergic diseases. Diesel exhaust is composed of vapors, gases, and fine particles emitted by diesel-fueled compressionignition engines. DEPs can act as nonspecific airway irritants at relatively high levels. At lower levels, DEPs promote release of specific cytokines, chemokines, immunoglobulins, and oxidants in the upper and lower airway. Release of these mediators of the allergic and inflammatory response initiates a cascade that can culminate in airway inflammation, mucus secretion, serum leakage into the airways, and bronchial smooth muscle contraction. DEPs also may promote expression of the T H 2 immunologic response phenotype that has been associated with asthma and allergic disease. DEPs appear to have greater immunologic effects in the presence of environmental allergens than they do alone. This immunologic evidence may help explain the epidemiologic studies indicating that children living along major trucking thoroughfares are at increased risk for asthmatic and allergic symptoms and are more likely to have objective evidence of respiratory dysfunction.

Childhood asthma and indoor woodsmoke from cooking in Guatemala

“…If we look at the tobacco database, the negative effects on asthma from early life and in utero passive tobacco exposure seem relatively well established (Bjorksten, 1999). These findings also support the theory of a causal effect on asthma from early exposure to respirable particles through T-cell differentiation, as indicated in DEP studies (Pandya et al, 2002). In summary, we have toxicological indications for a causal effect of respirable particles on asthma and also evidence for acute toxic effects that may exacerbate existing asthmatic disease.…”

“…Diesel exhaust particles is also indicated as an adjuvant with environmental allergens, inducing and/or increasing atopic individuals' allergic reactions (Takano et al, 1997;Ishizaki et al, 1987), an important effect that remains to be studied for biomass smoke. There may be a link between the ''hygiene hypothesis'' (Strachan, 1989) and particle pollution, as diesel exhaust particles appear to enhance the differentiation of CD4 þ T lymphocytes into the IgE producing Th2 phenotype associated with atopy (Pandya et al, 2002). This supports the hypothesis of a potential longterm effect of exposure to extreme (Indoor Air Pollution) in infancy for the development of atopic disorder, including asthma.…”

“…These papers, mainly of ecologic design, have influenced the scientific communities' ways of thinking about air pollution in such a way that this exposure is often not considered an important risk factor for asthma. This is a paradox when we look at our findings, studies of passive tobacco smoke and diesel exhaust (Pandya et al, 2002;Cook et al, 1999), and the relatively strong evidence that outdoor air pollution triggers asthma attacks in asthmatic individuals (Ostro et al, 1994;Lebowitz et al, 1985). In addition to the overall controversies of whether smoke pollution has any measurable negative effects on asthma symptoms in a population, there is also the key question of whether the smoke may actually cause asthma, or if the smoke merely induces exacerbations in children who already have the disease.…”

Ambient Air Pollution: Health Hazards to Children

“…Toxicity of particles may vary with composition. 37,38 Particle pollution contributes to excess mortality and hospitalizations for cardiac and respiratory tract disease. 14, [39][40][41] The mechanism for particulate matter-associated cardiac effects may be related to disturbances in the cardiac autonomic nervous system, cardiac arrhythmias, or increased blood concentrations of markers of cardiovascular risk (eg, fibrinogen).…”

Maritime pollutants in shipping and commercial European ports based on relevant physical and biogeochemical environmental parameters (IUPAC Technical Report)

“…The engines at ports create vast amounts of air pollutants that affect the health of workers and people living in nearby communities, contributing dramatically to regional air pollution. Various studies show that diesel exhaust increases cancer risks and it is linked with asthma [82]. Major air pollutants from diesel engines at ports that can affect human health include PM, VOCs, NOx and SOx.…”