With the goal of malaria eradication firmly on the table, several aspects are undermining this, including the resurgence of malaria cases in some malaria endemic countries and artemisinin combination therapy (ACT) failure within the greater Mekong subregion of Asia. Plasmodium falciparum (Pf) ACT resistance presents as a slow parasite clearance time (> 5 hours) in vivo and in vitro greater than 1% survival of early ring stage parasites, 0-3 hours post red blood cell invasion, after a 6-hour dose of 700nM of artemisinin derivative (ART). Both these phenotypes are correlated to mutations within the PfK13 propeller domain, but not exclusively as some genetic predisposition is proposed to pre-empt the K13 mutation acquisition. The in vitro acquisition of K13 mutations through escalating ART challenge has only resulted from one study where O2 levels throughout incubation were 21% in comparison to 1-5% in other studies. Routinely the in vitro culture of Pf utilizes a single gaseous environment that is constant and maintained at, for example, 5% O2 and 5% CO2. However, in vivo the gaseous microenvironment has a diverse range of concentrations and ratios of O2 and CO2 depending on the location within the circulatory system and the presence of certain pathologies. To study the impact of alterations in the gaseous environment on parasite susceptibility to ART, the ring stage survival assay (RSA) was performed on Pf parasites, designated resistant or sensitive (K13 mutant or WT), cultured under different O2 and CO2 concentrations. To advance knowledge on the effect changing gaseous environments has on ART sensitivity and resistance at different stages of Pf asexual lifecycle, the RSA was also performed at a range of O2 and CO2 concentrations at selected times post red blood cell invasion. The effects of gaseous environments on parasite in vitro resistance and susceptibility profiles, relationship to K13 mutations, and biological evaluation of the underlaying mechanisms behind the altered responses will be discussed.