Placentitis is an inflammation of the placenta. The main forms of placentitis are:

Villitis, inflammation of chorionic villi. Intervillositis, inflammation of the intervillous space.It may be caused by vertically transmitted infections. Because of the close proximity, placentitis often occurs simultaneously as funisitis (inflammation of the umbilical cord) and chorioamnionitis (inflammation of the fetal membranes). Chronic lymphocytic placental inflammation occurs in 5% to 15% of pregnancies, and are generally not associated with documented infection. Villitis of unknown etiology
Villitis of unknown etiology (VUE), also known as chronic villitis, is a placental injury. VUE is an inflammatory condition involving the chorionic villi (placental villi). VUE is a recurrent condition and can be associated with intrauterine growth restriction (IUGR). IUGR involves the poor growth of the foetus, stillbirth, miscarriage, and premature delivery. VUE recurs in about 1/3 of subsequent pregnancies.VUE is a common lesion characterised by inflammation in the placental chorionic villi. VUE is also characterised by the transfer of maternal lymphocytes across the placenta.VUE is diagnosed in 7–10% placentas in pregnancies. Roughly 80% of the VUE cases are in term placentas (greater than 37 weeks of pregnancy). A case of VUE in a placenta less than 32 weeks old should be screened for infectious villitis. Chronic histiocytic intervillositis
Chronic Histiocytic Intervillositis (CHI or CHIV) also known as Chronic Intervillositis of Unknown (A)etiology (CIUE) and Massive Chronic Intervillositis (MCI) is defined as a diffuse infiltration of mononuclear cells (histiocytes, lymphocytes, monocytes) of maternal origin into the intervillous space within the placenta.
Peak expiratory flow rate (PEFR) is a hand held device which measures  how fast a person can exhale and is a reliable test for occupational asthma. Serial PEFR can be measured to see if there is a difference in ability to exhale at work compared to that in a controlled environment. A non-specific bronchial hyperreactivity test can be used to support the diagnose occupational asthma. It involves measuring the forced expiratory volume in 1 second (FEV-1) of the patient before and after exposure to methacholine or mannitol. Presence of airway responsiveness i.e. significant drop in FEV-1 can be seen in patients with occupational asthma.Specific inhalation challenges test consist of exposing the subjects to the suspected occupational agent in the laboratory and/or at the workplace and assess for asthma symptoms as well as a reduction in FEV1.Other tests such as skin prick test, serum immunologic testing and measurement of sputum eosinophils can also be useful in establishing the diagnosis of occupational asthma. Prevention
Several forms of preventive measures have been suggested to prevent development of occupational asthma and also detect risk or disease early to allow intervention and improve outcomes. These include: comprehensive programs, education and training, medical examinations, use of medications, reduction of exposures and elimination of exposures. Asthma symptoms and airway hyperresponsiveness can persist for several years after removal from the offending environment. Thus, early restriction from exposure to the trigger is advisable. Completely stopping exposure is more effective treatment than reducing exposure, but not always feasible.