Nitrogen Dioxide (NO₂)

CAS Number: 10102-44-0
Nitrogen dioxide (NO₂) is a reddish-brown, acrid gas produced during combustion, welding, arc cutting, blasting operations, and the use of gas-powered equipment in confined spaces. It is also generated in agricultural silos (silo gas), chemical manufacturing, and during nitric acid production. NO₂ is a potent respiratory irritant that can cause pulmonary edema hours after exposure, sometimes with a deceptively mild initial presentation. Repeated or chronic exposure is associated with reduced lung function and increased susceptibility to respiratory infections. Due to its delayed health effects, real-time monitoring and immediate evacuation protocols are critical in high-risk environments.

Nitrogen dioxide (NO₂) can build up in areas with diesel exhaust, propane-powered equipment, or hot work, creating an inhalation hazard in enclosed or poorly ventilated spaces. Rent NO₂ detection equipment from RAECO Rents to support spot checks and continuous monitoring in warehouses, maintenance shops, manufacturing areas, and during confined space entry. Rental instruments are bump tested and span calibrated before each rental.

Regulatory Exposure Limits

As of March 17, 2026

OSHA PEL
TWA: N/A
STEL: N/A
C: 5 ppm (9 mg/m³)
NIOSH REL
TWA: N/A
STEL: 1 ppm (1.8 mg/m³)
C: N/A
ACGIH TLV
TWA: N/A
STEL: N/A
C: N/A

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