asked the Secretary of State for the Environment whether he will publish details of county boroughs and cities in England and Wales in which, during each of the past three years, smoke level have risen above 40 microgrammes per cubic metre of air; how often the level has risen above 100 microgrammes in the city of Portsmouth; what has been the highest level there; how this compares with the highest levels elsewhere; and whether he will make a statement.
Of the 101 county boroughs and cities in England and Wales, Warren Spring Laboratory, during the last three years, received information about smoke concentrations from an average of 70. All sites monitored by these authorities recorded concentrations above 40 microgrammes per cubic metre on certain days. Of the five gauges operated by the Portsmouth City Council, that recording the highest concentrations registered over 100 microgrammes on 72 days in 1968–69, on 64 days in 1969–70 and on 38 days in 1970–71. These figures are lower than those for many other county boroughs and cities.