ISC-Aermod view dispersion model has been used to study the ground level concentration of hydrocarbon (HC). The purpose was to predict the air quality effects from off-grid diesel power generators operated by a textile factory in Lagos, Nigeria on its host airshed. Emissions from 22 point sources in 5 sections of the factory were considered with 6 different scenarios. 4 years of hourly meteorological observations were used for the investigation of dispersion. The model output showed the highest value of maximum ground level concentration at 90 m south east of the factory. The predicted impact using the worst case scenario showed that the ambient HC of the host air shed will change by 0.01-0.05% of Nigeria’s Federal Ministry of Environment (FMENV) standard. HC emissions from factory will not significantly affect the host air shed as the maximum concentrations from the worst case scenario were still lower than the national standard. However, since emissions from other factories will also be released into the same host environment, an integrated approach factoring the contributions from other factories should be employed in host air quality management.