There could be many reasons to this reactions besides chemicals in perfume and clothing. One of them could be because of volatile chemicals emitted by skin bacteria - even if we can't smell them, nose and lung receptors can react to it. Another reason could be allergy to human dander - the minute particles we constantly shed from our skin and scalp.
Allergen in human dander can arise in the epidermis itself rather than from a microorganism or other external agent. 5-10% of humans are allergic to human dander to some extent, more could be allergic to agents.
Surveys reveal that PATM might be associated with diet, especially dairy, coffee and alcohol. Antibiotic use might be contributing to the onset of PATM. Probiotic supplementations has mixed results, but Saccharomyces boulardii seems most helpful.
Social sneezing and nose-scratching factors can not be also excluded. There is no clear scientific evidence that sneezing is contagious in the same fashion as catching a yawn, but this does not mean it can't happen.
Most frequent co-occurring symptoms of those people are allergic to, are itchy skin - similar to known reactions to allergens in dander.