Very little pressure is required to ignite a disposable lighter. Even a very young child can light a disposable lighter. Disposable lighters look like toys to young children 3 or 4 years of age, who are developing color awareness. Remember there is a strike zone from the floor to an adult's shoulder height. Any space from the floor to your shoulder should be kept free of all fire setting materials.
Fire play is a very serious matter.
Don't assume that this is just a phase with your child. Children who set fires or play with fire can be a very serious threat to others and themselves. Children do not have the cognitive powers to understand why they set fires. Children who set fires must receive therapy. Contact the Fire Safety Division if you have questions regarding this matter.