A number of studies indicate cooking is a major source of exposure to particulate matter, but few studies have measured indoor air pollution in restaurants, where cooking predominates. We made 73 visits by car to 65 different non‐smoking restaurants in 10 Northern California towns while carrying portable continuous monitors that unobtrusively measured ultrafine (down to 10 nm) and fine (PM2.5) particles to characterize indoor restaurant exposures, comparing them with exposures in the car. The mean ultrafine number concentrations in the restaurants on dinner visits averaging 1.4 h was 71 600 particles/cm3, or 4.3 times the mean concentration on car trips, and 12.3 times the mean background concentration in the residence. Restaurants that cooked dinner in the same room as the patrons had higher ultrafine concentrations than restaurants with separate kitchens. Restaurant PM2.5 mass concentrations averaged 36.3 μg/m3, ranging from 1.5 to 454 μg/m3, but were relatively low on most visits: 43% of the indoor means were below 10 μg/m3 and 66% were below 20 μg/m3, with 5.5% above 100 μg/m3. Exposure to fine and ultrafine particles when visiting a restaurant exceeded the exposure a person received while traveling by car to and from the restaurant.

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Objectives. To estimate the risk of exposure to fentanyl among syringe exchange program (SEP) participants in New York City. Methods. We recruited a convenience sample from 11 SEPs in New York City between March and June 2017. Consenting participants (n = 434) received a labeled syringe for their next injection. We tested collected syringes with gas chromatography–mass spectrometry and liquid chromatography–quadrupole–time-of-flight mass spectrometry. Fentanyl or fentanyl analogs detected in quantities greater than 10% of the residue mass were reported. Results. The final analysis included 271 syringes; 46 (17.0%) contained fentanyl or a fentanyl analog. Fentanyl was the most frequently identified fentanyl compound, identified in 36 (13.3%) syringes. Furanylfentanyl was detected in 10 (3.7%) syringes, and 4-fluoroisobutyryl fentanyl was detected in 5 (1.8%) syringes. Conclusions. The risk of exposure to fentanyl in syringes used by SEP participants was significantly lower significantly lower than the amount of fentanyls identified among overdose decedents in New York City. Further research is needed to understand how people who use drugs have adapted to fentanyl in the drug market. Understanding the risk of exposure to fentanyls is critical to development of targeted public health messaging.