(b) additional rulemaking activities in response to court decisions, (c) actual performance of the pollution control technologies installed, (d) changes in costs for new pollution controls, (e) new generating technology developments, (f) total MWs of capacity retired and replaced, including the type and amount of such replacement capacity and (g) other factors. Management’s current ranges of estimates of new major environmental investments beginning in 2021, exclusive of debt AFUDC, are set forth below: Attracting, developing and retaining employees with the skills and experience needed to provide service to our customers efficiently and effectively is crucial to our long-term success and is central to our long-term strategy. AEP invests in employees and continues to build a high performance and inclusive culture that inspires leadership, encourages innovative thinking and welcomes everyone. The following table shows AEP’s number of employees by subsidiary as of December 31, 2020: Of AEP’s 16,787 employees, less than 1% are Traditionalists (born before 1946), approximately 27% are Baby Boomers (born 1946-1964), approximately 37% are Generation X (born 1965-1980), approximately 34% are Millennials (born 1981-1996) and approximately 1% are Generation Z (born after 1996). Achieving Zero Harm means every employee returns home at the end of their shift in the same or better condition than when they came to work. Zero Harm is what we value most and commit to wholeheartedly. It is hard work, as it requires full focus every moment of every day. We hold ourselves accountable and we are always striving to be better. For AEP, Zero Harm is not an option; it is a mandate we live by. AEP has put tools, training and processes in place to strengthen our safety-first culture and mindset. AEP’s focus is on learning from events and developing leading indicators to be even more proactive in preventing harm. One common industry safety metric utilized by AEP to track incidents is the Days Away/Restricted or Transferred (DART) rate. A DART event is an event that results in one or more lost days, one or more restricted days or results in an employee transferring to a different job within the company. The DART rate is a mathematical calculation (number of DART events multiplied by 200,000 work hours and divided by total YTD hours worked) that describes the number of recordable injuries per 100 full-time employees. In 2020, AEP recognized its best safety performance in the past five years with an employee DART Rate of 0.310. 15 Safety HUMAN CAPITAL MANAGEMENT Projected (2021 - 2027) Environmental Investment Company Low High (in millions) AEP $ 350  $ 700  APCo 175  290  I&M 25  45  PSO 5  10  SWEPCo 45  90  Subsidiary Number of Employees AEPSC 6,295  AEP Texas 1,570  APCo 1,652  I&M 2,217  OPCo 1,646  PSO 1,023  SWEPCo 1,440  Other 944  Total AEP 16,787 