Research presented at the ATS 2021 International Conference, found that the use of e-cigarettes is associated with wheezing and shortness of breath in young adults and adolescents, even in those who do not smoke cigarettes or marijuana. They found that, after controlling for age, gender and race/ethnicity, past 30-day e-cigarette use was associated with increased odds of self-reported asthma, wheezing and shortness of breath, compared with survey respondents who reported never using e-cigarettes. This relationship held true, even after statistically controlling for those who said they had ever used cigarettes or cannabis. After controlling for past 30-day cigarette and cannabis use, past 30-day e-cigarette use was no longer associated with asthma–but was still associated with shortness of breath and increased wheezing. The prevalence of asthma, wheeze and shortness of breath was 24 per cent, 13 per cent and 20 per cent, respectively. Among past 30-day e-cigarette users, 15 per cent reported using cigarettes and 37 per cent reported cannabis use. The number of adolescents and young adults who use e-cigarettes continues to increase, with estimates of 5.4 million new users in 2019. E-cigarettes are the most commonly used tobacco product in this age group, but researchers have found it difficult to disentangle the risk of asthma and related respiratory symptoms associated with e-cigarettes due to a high frequency of cigarette and cannabis smoking among e-cigarette users age 14-21.