The mass and time available for planet formation is strongly dependent on the stellar birth environment. Both external photoevaporation induced by far ultraviolet photons and star-disc encounters are capable of accelerating protoplanetary disc (PPD) dispersal. I quantify the influence of the two mechanisms in observed young stellar environments and find that external photoevaporation generally dominates over encounters. I further find that the influence of photoevaporation causes PPDs to disperse quickly (within ~3 Myr) for the majority of stars in many local stellar clusters and associations. PPDs around low mass stars are more quickly dispersed due to a shallower gravitational potential and this effect should be detectable in samples of observed discs. Finally, I discuss how the primordial gas properties on galactic scales can be used to infer timescales for disc dispersal outside of the Solar neighbourhood, and the consequences for expected exoplanet frequency.