Reported in EPA TSCA Inventory.

OSHA PEL: TWA 75 ppm
ACGIH TLV: TWA 75 ppm
DFG MAK: 75 ppm (210 mg/m³)

For occupational chemical analysis use NIOSH: 1,3-Cyclopentadiene, 2523.

 The Cyclopentadiene, with the CAS registry number 542-92-7,is also known as 1,3-Cyclopentadiene. It belongs to the product categories of Organic matters. This chemical's molecular formula is C₅H₆ and molecular weight is 66.10.Its EINECS number is 542-92-7. What's more,Its systematic name is Cyclopentadiene.It is a colourless liquid which is stable at room temperature and incompatible with oxidizing agents, acids and a wide variety of other compounds.It may form peroxides in storage.And it may undergo spontaneous polymerisation. It Decomposes on heating,mixtures with air are explosive.It is used for organic synthetic intermediates, and manufacturing pesticides.In addition, it is mainly used for resin industry, synthetic rubber, etc.

Physical properties about Cyclopentadiene are:
(1)ACD/LogP:  2.087; (2)# of Rule of 5 Violations:  0; (3)ACD/LogD (pH 5.5):  2.09; (4)ACD/LogD (pH 7.4):  2.09; (5)ACD/BCF (pH 5.5):  22.72; (6)ACD/BCF (pH 7.4):  22.72; (7)ACD/KOC (pH 5.5):  325.50; (8)ACD/KOC (pH 7.4):  325.50; (9)#H bond acceptors:  0; (10)#H bond donors:  0; (11)#Freely Rotating Bonds:  0; (12)Index of Refraction:  1.503; (13)Molar Refractivity:  22.266 cm³; (14)Molar Volume:  75.303 cm³; (15)Surface Tension:  34.859001159668 dyne/cm; (16)Density:  0.878 g/cm³; (17)Flash Point:  -32.166 °C; (18)Enthalpy of Vaporization:  27.4 kJ/mol; (19)Boiling Point:  41.499 °C at 760 mmHg; (20)Vapour Pressure:  418.459991455078 mmHg at 25°C.

You can still convert the following datas into molecular structure:
(1)SMILES:C1C=CC=C1;
(2)Std. InChI:InChI=1S/C5H6/c1-2-4-5-3-1/h1-4H,5H2 ;
(3)Std. InChIKey:ZSWFCLXCOIISFI-UHFFFAOYSA-N.

The toxicity data of Cyclopentadiene as follows: