RESUMO
The outbreak of SARS-CoV-2 (COVID-19) has attracted much attention to study its possible presence and airborne transmission. The possibility of COVID-19 airborne transmission in indoor environments is debatable. The present study examined the concentration of viral RNA-containing particles produced directly or indirectly by breathing or coughing of confirmed COVID-19 patients or by carriers without symptoms. Some studies do not accept this method of transmission (COVID-19 airborne transmission). The present study aimed to measure the possible exposure of health care personnel to SARS-CoV-2 particles that may have been suspended in the air to respond to the hypothesis of COVID-19 airborne transmission. Airborne particle sampling was performed using impingement method based on NIOSH (chapter BA) and ASHRAE. Selection of sampling sections was in line with the WHO guidelines. The samples were analyzed using RT-PCR technique. Based on the given results, airborne particles of COVID-19 may present in the air and affect the health of hospital personnel. In fact, the analysis of gene expression in ambient conditions and thereby aerosol transmission of SARS-CoV-2 through air is possible and may lead to occupational exposure of health care personnel. Furthermore, it was found that airborne emission of COVID-19 through the breathing zone of patients, particularly in ICU wards with confirmed cases of COVID-19, may be higher than in other ICU wards. Also, the demonstrated results showed that there is a possibility of reaerosolization (reintroduction) of previously airborne SARS-CoV-2 particles into the atmosphere due to health care personnel frequently walking between different wards and stations of ICU.
RESUMO
BACKGROUND: The aims of this study were evaluation of exposed to xylenes in low concentration and compare urinary level of methyl hippuric acid in taxi drivers and petrol stations workers in West of Iran. METHODS: This observation study was carried out on samples of the exposed men to xylenes in two occupational groups in Hamadan City (west of Iran) from March 2003 to March 2004. Subjects included 45 taxi drivers and 25 petrol station workers. The study group was selected from 54 workers at petrol stations and 300 drivers by simple random sampling. Xylenes was analyzed using gas chromatography equipped with a Flame Ionization Detector (FID). The urinary methyl hippuric acid (MHA) was analyzed with High performance Liquid Chromatography (HPLC) equipped with an ultraviolet (UV) detector. RESULTS: Total xylene exposure was 1.05±0.55 ppm (mean±SD) with a range of 0.20-2.55 ppm that was about 4 times more than taxi drivers' exposure. The poor correlation coefficient was seen between xylenes concentration and urinary MHA for drivers (r2= 0.09 to 0.42) but significant associations were noted between urinary MHA and xylene in the breathing zone of petrol station workers (r2= 0.69 to 0.77; P< 0.05). CONCLUSION: High xylenes levels are emitted in petrol stations at Iran. Urinary MHA level has a poor correlation with exposure to xylenes in drivers but has good correlation in petrol station workers.
