Screening of health workers exposed to SARS-CoV-2 in a university hospital in the south of France.

INTRODUCTION: SARS-CoV-2, which causes COVID-19, is a virus that has caused a global pandemic. Health workers (HWs) are major players in the fight against this infection and are occupationally exposed to the virus in the course of their work. In this context, this study presents surveillance data on 1714 workers in a hospital center in the south of France for the period from March 17 to April 20, 2020. MATERIALS AND METHODS: Symptomatic HWs, contact cases and those with high anxiety were tested. Diagnosis of COVID-19 was performed by RT-PCR after nasopharyngeal sampling. RESULTS: During this period, 30.4% of hospital staff received 3028 nasal swabs. Of these, 8.0% were infected with SARS-CoV-2. Among the SARS-CoV-2 positive HWs, 24.3% were asymptomatic. Among COVID unit and non COVID unit, the positive HWs for SARS-CoV-2 were, respectively, 5.8% and 8.2% (p = 0.2). HWs over 50 years of age were less likely to be positive for SARS-CoV-2 (3.8%) than other younger HWs (9.1%) (p < 0.001). No serious cases of COVID-19 were reported in our population during this period. DISCUSSION: Our study suggests that HWs who tested positive for COVID-19 are often asymptomatic. Therefore, PPE is pivotal to prevent HWs to patients and HWs to HWs transmission during workshifts. Contact tracing and screening is essential to limit the spread of the virus within the hospital. On the other hand, HWs working in COVID-19 units are not more often infected probably because they have a higher risk awareness than other HWs.

Physico-Chemical Characterization of Fine and Ultrafine Particles Emitted during Diesel Particulate Filter Active Regeneration of Euro5 Diesel Vehicles.

Diesel particulate filters (DPFs) are commonly employed in modern passenger cars to comply with current particulate matter (PM) emission standards. DPFs requires periodic regeneration to remove the accumulated matter. During the process, high-concentration particles, in both nucleation and accumulation modes, are emitted. Here, we report new information on particle morphology and chemical composition of fine (FPs) and ultrafine particles (UFPs) measured downstream of the DPF during active regeneration of two Euro 5 passenger cars. The first vehicle was equipped with a close-coupled diesel oxidation catalyst (DOC) and noncatalyzed DPF combined with fuel borne catalyst and the second one with DOC and a catalyzed-diesel particle filter (CDPF). Differences in PM emission profiles of the two vehicles were related to different after treatment design, regeneration strategies, and vehicle characteristics and mileage. Particles in the nucleation mode consisted of ammonium bisulfate, sulfate and sulfuric acid, suggesting that the catalyst desulfation is the key process in the formation of UFPs. Larger particles and agglomerates, ranging from 90 to 600 nm, consisted of carbonaceous material (soot and soot aggregates) coated by condensable material including organics, ammonium bisulfate and sulfuric acid. Particle emission in the accumulation mode was due to the reduced filtration efficiency (soot cake oxidation) throughout the regeneration process.