Chris Brown's ex-girlfriend has accused him of causing their daughter to develop asthma. Nia Guzman has filed court documents to restrict the 'Fine China' singer's access to 19-month-old Royalty because she claims he has exposed the tot to an extreme amount of secondhand smoke, which has caused her to develop the breathing condition. As well as complaining Royalty usually smells of smoke when she returns from visiting her father, TMZ reports Nia's documents also state she is worried Chris is abusing drugs and has relapsed, especially with sizzurp, a cocktail of codeine-based cough syrup, soda, and Jolly Ranchers candy. In her legal documents, Nia has asked a judge to force her former lover to hire a full-time nanny or pull back his right to be around their little girl. She also wants the judge to force Chris to take random drug tests and prohibit him from using drugs, smoking consuming alcohol around their daughter. She is also seeking to have her child support increased from $2,500 a month to almost $16,000. Chris, 26, recently spoke of how "humbling" he has found being a father. He said: "I have a co-parenting job that's pretty amazing but, you know, learning how to be a dad, especially learning how to take care of somebody else. I barely know how to brush my teeth in the morning! It's actually great. It's very humbling ... It's very calming. "I think I was a lot (more) ... rambunctious, very hyper as a kid but, now seeing that 10 times over, my daughter's kinda, like, mellowing me out."