Detectives investigating reports of a suspected noxious substance attack are appealing for witnesses to contact them.
Police were called at approximately 19:10hrs on Friday, 8 June to reports of a suspected noxious substance attack on Brentford High Street.
Officers attended along with the London Ambulance Service.
A woman, aged in her early 30s, was treated at the scene by paramedics for injuries that are not life-threatening or life-changing. She did not require hospital treatment.
A 20-year-old man was arrested at the scene on suspicion of causing grievous bodily harm. He was taken to a west London police station and has been bailed to a date in early July.
The suspect and victim are known to each other.
Anyone who witnessed the attack is asked to contact police on 020 8247 6222 or via 101 quoting 6934/8June or call Crimestoppers on 0800 555 111.