A method for providing information indicative of concentration of at least one allergen in the environment, said method comprising: a) recording on a mobile device information relating to detection of a respiratory difficulty symptom in a person, said recording comprising receiving from said person, via a graphical interface of said mobile device, at least one subjective information relating to said detected respiratory difficulty symptom, said at least one subjective information comprising a probable cause of said detected respiratory difficulty symptom and an indication of the severity of said detected respiratory difficulty symptom, said recording further comprising automatically generating at least one objective information relating to said detected respiratory difficulty symptom, said at least one objective information comprising a place where said symptom was detected and a date and time at which said symptom was detected, said place and said date and time being automatically detected by said mobile device; b) sharing on a sharing server at least part of said information relating to said detected respiratory difficulty symptom and recorded on said mobile device, said at least part of said information relating to said detected respiratory difficulty symptom and recorded on said mobile device comprising said place where said symptom was detected, said date and time at which said symptom was detected and said indication of said probable cause of said detected respiratory difficulty symptom; and c) at a further mobile device (4a, 4b, 4c), receiving from said sharing server said shared at least part of said information relating to said detected respiratory difficulty symptom and displaying said shared at least part of said information relating to said detected respiratory difficulty symptom on a map shown by a display of said further mobile device (4a, 4b, 4c). a) recording on a mobile device information relating to detection of a respiratory difficulty symptom in a person, said recording comprising receiving from said person, via a graphical interface of said mobile device, at least one subjective information relating to said detected respiratory difficulty symptom, said at least one subjective information comprising a probable cause of said detected respiratory difficulty symptom and an indication of the severity of said detected respiratory difficulty symptom, said recording further comprising automatically generating at least one objective information relating to said detected respiratory difficulty symptom, said at least one objective information comprising a place where said symptom was detected and a date and time at which said symptom was detected, said place and said date and time being automatically detected by said mobile device; b) sharing on a sharing server at least part of said information relating to said detected respiratory difficulty symptom and recorded on said mobile device, said at least part of said information relating to said detected respiratory difficulty symptom and recorded on said mobile device comprising said place where said symptom was detected, said date and time at which said symptom was detected and said indication of said probable cause of said detected respiratory difficulty symptom; and c) at a further mobile device (4a, 4b, 4c), receiving from said sharing server said shared at least part of said information relating to said detected respiratory difficulty symptom and displaying said shared at least part of said information relating to said detected respiratory difficulty symptom on a map shown by a display of said further mobile device (4a, 4b, 4c).