Occurrence of dog, cat, and mite allergens in public transport vehicles.

BACKGROUND AND METHODS: Helsinki City Transport buses, trams, and underground trains carry 687,000 passengers on a weekday. Of the passengers, 0.13% travel with a pet. We interviewed passengers and measured allergen levels in vehicles to determine what difficulties allergens cause to passengers with allergy and asthma. RESULTS: Of 2,021 interviewed passengers, 14% complained about inconvenience caused by pets, usually health problems. Of 324 adult passengers with allergy or asthma, 53% had experienced symptoms in public transport; the corresponding figure for 75 children was 32%. The median concentration of the main dog allergen, Can f 1, in dust from seats and floors in public transport vehicles was 2,400 ng per g of dust (range 20-8,500 ng/g). For the main cat allergen, Fel d 1, the median was 870 ng/g (range 3-2,600 ng/g). These levels can be regarded as low or moderate, and they cause symptoms in sensitive persons. Concentrations of mite allergens were undetectable or low. Allergen levels were lower in vehicles where pets were not allowed than in vehicles where pets were allowed, lower in dust from uncovered seats than in dust from seats with a covering, and lower after cleaning vehicle floors and seats than before cleaning. CONCLUSIONS: Dog and cat allergens are present in public transport vehicles in Helsinki at levels that cause symptoms in sensitive persons. Prohibiting pets would probably bring only a modest reduction in levels, as few pets are carried, and much allergen contamination comes from passengers' clothes.

Penetration of nitrogen oxides and particles from outdoor into indoor air and removal of the pollutants through filtration of incoming air.

We studied the effect of ventilation and air filtration systems on indoor air quality in a children's day-care center in Finland. Ambient air nitrogen oxides (NO, NO2) and particles (TSP, PM10) were simultaneously measured outdoors and indoors with automatic nitrogen oxide analyzers and dust monitoring. Without filtration nitrogen oxides and particulate matter generated by nearby motor traffic penetrated readily indoors. With chemical filtration 50-70% of nitrogen oxides could be removed. Mechanical ventilation and filtration also reduced indoor particle levels. During holidays and weekends when there was no opening of doors and windows and no particle-generating activity indoors, the indoor particle level was reduced to less than 10% of the outdoor level. At times when outdoor particle concentrations were high during weekdays, the indoor level was about 25% of the outdoor level. Thus, the possible adverse health effects of nitrogen oxides and particles indoors could be countered by efficient filtration. We also showed that inclusion of heat recovery equipment can make new ventilation installations economical.

The South Karelia Air Pollution Study: changes in respiratory health in relation to emission reduction of malodorous sulfur compounds from pulp mills.

The authors assessed the health effects of emission reduction of malodorous sulfur compounds in a prospective cohort study with a controlled natural experiment. A total of 810 subjects (83%) participated in the follow up: 316 from the severely polluted, 306 from the moderately polluted, and 188 from the nonpolluted communities. In the severely polluted community, the annual ambient air concentration of total reduced sulfur compounds decreased from 11 microg/m3 to 6 microg/m3. Compared with the nonpolluted community, the relative decrease in acute respiratory infections, adjusted for a change in smoking habits, was 0.53 episodes/person-year (95% confidence interval = 0.22, 0.83) in the severely polluted community and 0.36 episodes/person-year (95% confidence interval = 0.06, 0.66) in the moderately polluted community. In addition, the frequency of nasal symptoms (p = .004) and cough (p = .037) decreased significantly. The results are consistent with the hypothesis that exposure to malodorous sulfur compounds increases the risk of acute respiratory infections and symptoms of the respiratory tract.

The South Karelia Air Pollution Study: effects of low-level exposure to malodorous sulfur compounds on symptoms.

Exposure to very low levels of ambient-air malodorous sulfur compounds and their effect on eye irritation, respiratory-tract symptoms, and central nervous system symptoms in adults were assessed. A cross-sectional self-administered questionnaire (response rate = 77%) was distributed during March and April 1992 to adults (n = 336) who lived in a neighborhood that contained a pulp mill and in a nonpolluted reference community (n = 380). In the exposed community, the measured annual mean concentrations of total reduced sulfur compounds and sulfur dioxide measured in two stations were 2 to 3 micrograms/m3 and 1 micrograms/m3, respectively. In the reference community, the annual mean concentration of sulfur dioxide was 1 micrograms/m3. The residents of the community near the pulp mill reported an excess of cough, respiratory infections, and headache during the previous 4 wk, as well as during the preceding 12 mo. The relative risk for headache was increased significantly in the exposed community, compared with the reference area: the adjusted odds ratio (aOR) was 1.83 (95% confidence interval [95% CI] = 1.06-3.15] during the previous 4 wk and 1.70 (95% CI = 1.05-2.73) during the preceding 12 mo. The relative risk for cough was also increased during the preceding 12 mo (aOR = 1.64, 95% CI = 1.01-2.64). These results indicated that adverse health effects of malodorous sulfur compounds occur at lower concentrations than reported previously.

South Karelia Air Pollution Study: daily symptom intensity in relation to exposure levels of malodorous sulfur compounds from pulp mills.

In a longitudinal study, we assessed the relation between daily exposure to ambient air malodorous sulfur compounds from pulp production and experience of symptoms in a small population living in the vicinity of a pulp mill. Special emphasis was laid on exposure-response pattern, where the intensity of the symptoms of interest was assessed in six consecutive questionnaires after three predefined levels of exposure to malodorous sulfur compounds [total reduced sulfur (TRS)] (reference: daily mean < 10 micrograms/m3, medium exposure: 10-30 micrograms/m3 high exposure: > 30 micrograms/m3). The study population included 81 adults, who responded to the baseline questionnaire (response rate 81%). The outcomes of interest were eye, respiratory, and central nervous symptoms. The mean daily intensity of the outcome symptoms, but not of control symptoms, was significantly higher on days of medium and high exposure compared with the reference days (paired t test). The probability ratios between experiencing more or fever symptoms during the medium and high exposure compared with reference days were increased for all the symptoms of interest with a consistent exposure response pattern. The probability ratios were for eye symptoms 3.17, 95% confidence intervals (CI) 1.21 to 7.47 (medium exposure), and 5.0, 95% CI 1.66 to 12.65 (high exposure); for nasal symptoms 3.13, 1.25 to 7.25 (medium), and 8.50, 3.19 to 18.64 (high); and for pharyngeal symptoms 2.0, 0.92 to 4.14 (medium) and 5.20, 1.95 to 11.99 (high). The results suggest that relatively low daily levels of malodorous sulfur compounds (TRS > 10 micrograms/m3) cause exposure-related short-term adverse effects.

The South Karelia Air Pollution Study: the effects of malodorous sulfur compounds from pulp mills on respiratory and other symptoms in children.

We assessed the role of long-term exposure to ambient air malodorous sulfur compounds released from pulp mills as a determinant of eye and respiratory symptoms and headache in children. Adverse health effects of environmental exposure to these compounds in children have not been reported previously. The parents of 134 children living in a severely polluted (n = 42), moderately polluted (n = 62) and rural nonpolluted (n = 30) community responded to a cross-sectional questionnaire. The response rate was 83%. The adjusted odds ratios (OR) for symptoms experienced during the previous 4 weeks and 12 months in the severely versus nonpolluted community were estimated in logistic regression analysis controlling for age and gender. The risk of nasal symptoms (4 weeks OR 1.40, 95% CI 0.59-3.31; 12 months OR 2.47, 95% CI 0.93-6.53), cough (4 weeks OR 1.83, 95% CI 0.75-4.45; 12 months OR 2.28, 95% CI 0.95-5.47), eye symptoms (12 months OR 1.15, 95% CI 0.43-3.05), and headache (12 months OR 1.77, 95% CI 0.69-4.54) was considerably increased in the severely polluted community, although not quite reaching statistical significance. The results suggest that exposure to malodorous sulfur compounds may affect the health of children.

The South Karelia Air Pollution Study: acute health effects of malodorous sulfur air pollutants released by a pulp mill.

We evaluated the acute health effects of a strong emission of malodorous sulfur compounds released from a pulp mill in South Karelia, Finland. The 24-hour ambient air concentrations of hydrogen sulfide for the two emission days were 35 and 43 micrograms/m3 (maximum 4-hour 135 micrograms/m3). A questionnaire was distributed after the high exposure and later after a low exposure period to 29 households with 75 subjects living in the nearby community. During the high exposure, 63% of the respondents reported experience of at least one symptom compared to 26% during the reference period. Every third participant reported difficulties in breathing. In the 45 subjects responding to both questionnaires more eye, respiratory and neuropsychological symptoms occurred during the exposure compared to the reference period. The strong malodorous emission from a pulp mill caused an alarming amount of adverse effects in the exposed population.

The South Karelia Air Pollution Study. The effects of malodorous sulfur compounds from pulp mills on respiratory and other symptoms.

The paper mills in South Karelia, the southeast part of Finland, are responsible for releasing a substantial amount of malodorous sulfur compounds such as hydrogen sulfide (H2S), methyl mercaptan (CH3SH), and methyl sulfides [(CH3)2S and (CH3)2S2], into ambient air. In the most polluted residential area the annual mean concentrations of hydrogen sulfide and methyl mercaptan are estimated to be 8 and 2 to 5 micrograms/m3 and the highest daily average concentration 100 and 50 micrograms/m3. The annual mean and highest daily concentrations of sulfur dioxide (SO2) are very low. We studied the effects of malodorous sulfur compounds on eye, nasal and respiratory symptoms, and headache in adults. A cross-sectional self-administered questionnaire was distributed in February 1987 and responded to by 488 adults living in a severely (n = 198), a moderately (n = 204), and a nonpolluted community (n = 86). This included questions about occurrence of the symptoms of interest during the previous 4 wk and 12 months and individual, behavioral, and other environmental determinants of the symptoms. The response rate was 83%. The odds ratios (OR) for symptoms experienced often or constantly in severely versus nonpolluted and moderately versus nonpolluted communities were estimated in logistic regression analysis controlling potential confounders. The odds ratios for eye (moderate exposure OR 11.70, Cl95% 2.33 to 58.65; severe exposure OR 11.78, Cl95% 2.35 to 59.09) and nasal symptoms (OR 2.01, Cl95% 0.97 to 4.15; OR 2.19, Cl95% 1.06 to 4.55) and cough (OR 1.89, Cl95% 0.61 to 5.86; OR 3.06, Cl95% 1.02 to 9.29) during the previous 12 months were increased, with a dose-response pattern.(ABSTRACT TRUNCATED AT 250 WORDS)

Exposure to hydrogen sulphide and respiratory function.

A study was carried out to assess possible effects of low concentrations of hydrogen sulphide on respiratory function. The cohort comprised 26 male pulp mill workers (mean age 40.3, range 22-60 years) with a daily exposure to hydrogen sulphide in the workplace, and 10 volunteers, who had asthma (three men, mean age 40.7, range 33 to 50 years, and seven women, mean age 44.1, range 31 to 61 years). The respiratory function of the pulp mill workers was monitored by measuring forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and bronchial responsiveness after at least one day off work and at the end of a workday. Bronchial responsiveness was tested by challenge with histamine. The 10 asthmatic subjects were exposed in laboratory conditions to 2 ppm of hydrogen sulphide for 30 minutes in an exposure chamber. Airway resistance (Raw) and specific airway conductance (SGaw) were assessed by a body plethysmograph, and the ventilatory capacities were measured with a flow volume spirometer. No significant changes in respiratory function or bronchial responsiveness related to exposure to hydrogen sulphide in the pulp mill workers were found. In the asthmatic subjects, Raw was increased by 26.3% and SGaw was decreased by 8.4% on average after exposure to hydrogen sulphide. These changes were not statistically significant. In two subjects, however, changes were greater than 30% in both Raw and SGaw, indicating bronchial obstruction. It is concluded that exposure for a relatively short time to hydrogen sulphide concentrations appreciably higher than those existing in ambient air do not cause noticeable effects on respiratory function.