We study the effects of artificial (fluorescent) light interference on a dual-header pulse interval modulation (DH-PIM) modulation scheme for an indoor optical wireless environment. Artificial-light-induced interference can be reduced using high-pass filtering (HPF), but it results in a new interference known as the baseline wander. We examine the effects of changing the HPF cut-on frequency in the absence and presence of multipath propagation. The results show that depending on the value of the HPF cut-on frequency, the severity of baseline wander will vary; thus there is a trade-off between the extent of artificial-light-interference rejection and the severity of baseline wander. We show that for DH-PIM, the power requirements are almost constant for HPF with cut-on frequency less than 1% of the bit rate and increase exponentially beyond this value.