Toxicants can cross the placenta and expose the developing fetus to chemical contamination leading to possible adverse health effects, by potentially inducing alterations in immune competence. Our aim was to investigate the impacts of maternal exposure to air pollution before and during pregnancy on newborn's immune system.

Background: Little is known about the relation between allergic rhinitis severity and airborne pollen in combination with air pollutants. Objective: To model the risk of suffering from severe seasonal allergic rhinitis (SAR) as a function of both pollen count and air pollution levels in a large nationwide sample of patients whose SAR was diagnosed by a physician and confirmed by skin prick test positivity or specific immunolglobulin E to common aeroallergens. Methods: The severity of SAR symptoms was estimated with the Symptomatic Global Score (SGS) among 36,397 patients suffering from an untreated and uncomplicated SAR between May and August 2004 in metropolitan France. Patients who had an SGS in the upper third quartile were classified as suffering from severe SAR. A multilevel model relating SAR severity, pollen and air pollution was used to take into account the hierarchical data structure. Results: 18.9% of the 17,567 urban patients retained for the analysis suffered from severe rhinitis. At the Lag0 (day of the visit), a rise of 60 grass pollen grains/m³ increased the risk of suffering from a severe SAR form by 8% in the multileveled model after adjusting for potential confounders and air pollution levels. Results were also confirmed in the subsample of individuals with documented sensitization to grass pollen. Conclusion: Grass pollen count aggravated SAR in terms of symptoms in our nationwide sample. These findings confirm the need for proper treatment and preventive measures in SAR patients sensitized to grass pollen.

In his important article [1], Gennaro D'Amato provides elements that contribute to reply to two burning questions of the present time. How bad is the fact of living in a city for asthma and, more generally, for respiratory allergy? And to what extent does climate change worsen asthma in individuals living in cities? The two questions are strictly related. How bad is living in a city for asthma? Several investigations have indicated that individuals living in cities have a higher risk of suffering from asthma and allergies compared to those living in the countryside, this being due to several factors. Besides the fact that individual susceptibility varies between urban and rural settings, there are environmental factors that are typical of living in a city. First of all, as perfectly indicated by D'Amato in his article, urban air pollution is composed of gases and particles. Whereas industrial pollution has decreased in recent decades, at least in industrialized countries, air pollution related to traffic is rising or remaining at the same level (www.eea.org). Gases and particulate matter have been shown by experimental and epidemiological studies to be involved in respiratory adverse effects. At the population lev

In his important article, Gennaro D’Amato pro- vides elements that contribute to reply to two burn- ing questions of the present time. How bad is the fact of living in a city for asthma and, more gener- ally, for respiratory allergy? And to what extent