Percutaneous absorption of m-xylene vapour in volunteers during pre-steady and steady state

Percutancous absorption of m-xylene (XYL) was determined in volunteers exposed to 29.4 mug cm(-1) XYL vapour on the forearm and hand for 20, 45, 120 and 180 min. The internal exposure was assessed by measuring the concentration of XYL in exhaled air. The systemic kinetics were determined using a reference exposure by inhalation. The dermal permeation rate and the cumulative absorption of XYL as a function of time were calculated using mathematical deconvolution. From these relationships, the average flux into the skin throughout the exposure (J(skin), average) and the maximal flux into the blood (J(bood.max)) were derived. Both fluxes were dependent on the duration of exposure, approaching each other at longer exposure durations. The values of J(skin.average), adjusted to a concentration of 1 mug cm(-3), were 0.091 mug cm(-2) h(-1) during 20-min exposure falling to 0.072, 0.066 and 0.061 mug cm(-2) h(-1) for 45, 120 and 180min, respectively. The values of J(blood, max) showed an opposite trend, gradually increasing from 0.034 mug cm(-2) h(-1) at an exposure duration of 20 min to 0.042, 0.059 and 0.063 mug cm(-2) h(-1) for 45, 120 and 180 min of exposure durations, respectively. (C) 2004 Elsevier Ireland Ltd. All rights reserve

Quantifying the impact of residential heating on the urban air quality in a typical European coal combustion region

The present investigation, carried out as a case study in a typical major city situated in a European coal combustion region (Krakow, Poland), aims at quantifying the impact on the urban air quality of residential heating by coal combustion in comparison with other potential pollution sources such as power plants, industry, and traffic. Emissions were measured for 20 major sources, including small stoves and boilers, and the particulate matter (PM) was analyzed for 52 individual compounds together with outdoor and indoor PM10 collected during typical winter pollution episodes. The data were analyzed using chemical mass balance modeling (CMB) and constrained positive matrix factorization (CMF) yielding source apportionments for PM10, B(a)P, and other regulated air pollutants namely Cd, Ni, As, and Pb. The results are potentially very useful for planning abatement strategies in all areas of the world, where coal combustion in small appliances is significant. During the studied pollution episodes in Krakow, European air quality limits were exceeded with up to a factor 8 for PM10 and up to a factor 200 for B(a)P. The levels of these air pollutants were accompanied by high concentrations of azaarenes, known markers for inefficient coal combustion. The major culprit for the extreme pollution levels was demonstrated to be residential heating by coal combustion in small stoves and boilers (>50% for PM10 and >90% B(a)P), whereas road transport (<10% for PM10 and <3% for B(a)P), and industry (4−15% for PM10 and <6% for B(a)P) played a lesser role. The indoor PM10 and B(a)P concentrations were at high levels similar to those of outdoor concentrations and were found to have the same sources as outdoors. The inorganic secondary aerosol component of PM10 amounted to around 30%, which for a large part may be attributed to the industrial emission of the precursors SO2 and NOx