The effects of tear gas are not just short term and could be experienced for up to two weeks after the event, according to a new study.

The study, presented at the European Respiratory Society (ERS) International Congress in Munich, investigated the duration of lung health effects in protesters directly exposed to tear gas.

Researchers in Turkey conducted a questionnaire survey with 546 people who had inhaled tear gas during public protests in June 2013. They collected information on smoking history, exposure to tear gas, reported symptoms and the duration of those symptoms.

Results found a range of respiratory symptoms, with 70% of respondents reporting respiratory difficulties, 80% reporting a lasting cough, 45% phlegm production and 43% chest pain. The median duration of both cough and chest pain was 15 days.

In a separate study, the harmful effects of tear gas were seen in people living in the surrounding areas, in addition to the people in the immediate vicinity of where the gas was used.

Researchers interviewed 105 people who lived and worked close to the location of repeated protests during the summer of 2013. They assessed lung health symptoms, duration and location of exposure, and also conducted lung function tests a week after the protests ended.

The results showed that 76% of participants reported breathlessness and 89% reported a lasting cough. The lung function tests found that 20 of participants showed some level of airway obstruction.

The findings suggest that the repeated use of tear gas during a protest with a long duration could have an impact on the health of people living and working in the area it is used.