|Mechanism for sealant mobility.|
- Annual PAH emissions from coal tar sealants exceed those from US vehicular emissions. Engine exhaust is usually cited as a major contributor to urban PAH air pollution.
- There was a 50% loss of PAHs from the product in the first 45 days after application via airborne releases.
- The maximum concentration measured after the application of a coal tar sealant was 297,000 ng per cubic meter. The OSHA limit is 200,000 ng per cubic meter7.
- Concentrations of one PAH above sealed lots were 10–15 times higher than those measured for global industrial cities, but were not higher than 2 Chinese industrial cities.
- Mean concentration 4 feet above a coal tar sealed surface is 138 ng per cu. meter but the value found that affects the unborn is just 36 ng per cu. meter8.
|Summary of USGS PAH concentrations above coal tar sealed and unsealed surfaces.|
|Annual PAH emissions from coal tar sealants exceed those from US vehicle emissions.|
Many countries have proposed a non-mandatory concentration limit for PAHs, whereas the health risk studies conducted in relation to PAH exposure, urge that these pollutants should be given a high priority when considering air quality management and reduction of impacts.10